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Conference unifix::sailing

Title:SAILING
Notice:Please read Note 2.* before participating in this conference
Moderator:UNIFIX::BERENS
Created:Wed Jul 01 1992
Last Modified:Mon Jun 02 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2299
Total number of notes:20724

1045.0. "storm mooring" by MSCSSE::BERENS (Alan Berens) Mon Nov 14 1988 16:07

re the loss of Fat Tuesday and other boats, especially notes 1022.12 and 
1022.13:

From what was said about the recent storm in Marblehead (and elsewhere)
that caused the loss of many boats, it is obvious that the moorings of
many boats are inadequate. I have been thinking about this occasionally
since the storm, and it seems to me that the loss of boats in this storm
was the result of owner carelessness, improper building of the boats,
improper mooring technique or simply sheer misfortune. (By the way, I
emphatically do not mean to imply that any particular individual owner
or builder is at fault.) 

It appears that the mooring blocks or anchors were sufficiently large --
I don't recall any reports saying that boats went shore dragging their
moorings. What does seem to have happened is that nylon mooring pennants
chafed through, that backup wire or chain pennants broke, and mooring
cleats pulled off of decks. 

From the reports I have heard, the recent storm was quite severe, and 
its severity was increased due to the peak of the storm occuring at or 
near high tide. The size of the waves added to an unusually high tide 
resulted in mooring chains being stretched tight. This in turn resulted
in very heavy loads on pennants and deck cleats. 

It is unfortunately true that the foredeck chocks on many boats have
rather sharp edges (such was the case on our C&C 26). A heavily loaded
nylon pennant without protection will chafe through very quickly when
led through such chocks. Chocks with sharp edges, chocks too small for
an adequate pennant, or no chocks at all is builder negligence or cost
cutting or both. Lack of proper chafe protection on mooring pennants 
(exceedingly common) is owner negligence. Owners can provide proper
chafe protection without much difficulty or cost, but replacing or
adding proper chocks may be difficult and expensive. 

It is also sad but true that some builders either do not provide backing 
plates for deck cleats or use plates that are too small. Sometime even 
the cleats are too small. I would think that it would be possible for 
owners to install adequate backing plates and to reinforce the foredeck 
enough to greatly reduce the chances of pulling cleats off the deck. On
our current boat it would be easy to install a heavy beam (of oak, say)
spanning the width of the foredeck. 

When a chain or wire pennant is subjected to high shock loads it will 
either fail or pull cleats off the deck due to the lack of elasticity in
the chain or wire. The Marblehead mooring regulations require a 
secondary pennant and the regulations strongly suggest a wire or chain 
secondary pennant since chain and wire are nearly immune to chafe and
since, as I have noted, the vast majority of owners do not provide any
chafe protection for their nylon pennants. It is interesting to note,
however, that the Marblehead regulations do allow the secondary pennant
to be nylon. By the way, if a chain or wire secondary pennant is used, 
it should, I think, be covered by something -- vinyl hose perhaps -- to 
keep it from chafing through the nylon primary pennant where they come 
in contact. Our secondary chain pennant is inside a nylon hose, but I
have no idea how effective this would be at preventing chafe of the
nylon primary pennant. 

Mooring pennants are fairly short to keep boats from hitting one another
when they drift around in calm weather. In heavy wind the bows of all
boats will point into the wind and there will be quite a distance (even
in Marblehead) between the stern of upwind boat and the bow of the
downwind boat. What is needed is a way to reduce the peak shock loading
on the pennant and the average loads as well. It seems to me that the
following might work: The primary pennant on our mooring (supplied by
the mooring company) is 1" diameter nylon about 10' long. What I propose
to do is to replace this pennant by a pennant 30 to 50 feet long. I
would coil the middle 20 to 40 feet of the pennant and seize the coil
into an oblong bundle of loops using fairly light line and leaving about
5' extending from the bundle on both ends (a picture here would be
nice). Under normal circumstances this will act like a 10' long pennant.
In storm conditions the two seizings will break and the boat will then
be moored to a 30 to 50 foot pennant. This should provide sufficient
length to reduce the shock loads (by stretching) enough to avoid pulling
the cleats off the deck or breaking the mooring chains. Of course,
proper chafe protection of the nylon pennant is critical. To increase
the elasticity of the pennant I would consider using 3/4" diamter nylon
instead of 1". All the larger diameter does is increase the length of
time required to chafe through -- the smaller diameter is amply strong.
(If S is the breaking strength of the seizing line, a seizing of N turns
shoud break at a load of about 2*S*N.) 

Which leaves sheer misfortune. For that there isn't much one can do 
except pay insurance premiums when due.

T.RTitleUserPersonal
Name
DateLines
1045.1Give 'em enough rope and . . .CSSE::COUTUREAbandon shoreMon Nov 14 1988 16:4111
    Alan,
    
    It seems to me that as soon as your coils broke free, you'd be
    banging into the boat directly behind you, unless, of course,
    he happened to have also coiled his pennant and it happened to break
    before or simultaneously with yours.  Granted, it would probably
    save your boat in a storm like the one that took Fat Tuesday, but
    I'd think your insurance company would have a thing or two to
    say about liability unless everyone else in Marblehead had to
    abide by the same rules.

1045.2ASABET::HOMon Nov 14 1988 17:3034
    
    I don't think the SS wire storm pennants are that good an idea.
    Wire does abrade very easily.  Wrapping it Tygon tubing, as is usually
    done with the storm pennants, isn't going to help much.  It's the
    wire that'll chafe through the tubing first before the chock does.
    I used to use coated wire jib sheets.  They chafed from the inside
    out and weren't good for more than about one season.  Once the metal
    to metal contact is established, the wire is as good as gone.  I've
    gone through too many wire fittings on my boat to think otherwise.
    
    There are mooring snubbers on the market that purport to increase
    the elasticity of pennants.  One  model uses a principle similar
    to the multiple coils of line, although on a smaller scale.  This
    is large rubber "band" with loops on both ends.  The pennant goes
    through one loop, winds around the band several times, and goes
    through the second loop before attaching to the boat in the normal
    fashion.  As the boat surges, the band stretches, the coils tighten,
    and the pennant elongates absorbing some of the shock.  This won't
    provide a lot of additional scope but the snubber and constriction
    of the coils is supposed to absorb a lot of shock.  I bought one
    about five years ago but have been too lazy to hook it up.  Maybe
    next year.
    
    Can some one explain why braided pennants are so popular?  It less
    stretchy than twisted nylon.  My suggestion for next year's mooring
    regs would be to use twisted nylon pennants, with snubbers, tied
    off to the base of the mast.  There would be a pvc or Tygon sleeve
    at the chock.  The storm pennant would be another of the same.  With
    the snubber and the couple of extra feet of line required to tie
    off at the mast, I think we'd have a lot more shock absorbtion than
    we do now.  I doubt if we'd be any worse off.
    
    - gene

1045.3MSCSSE::BERENSAlan BerensMon Nov 14 1988 17:5524
re .1:

Well, one does need to plan the length of the pennant carefully. Our
stern is easily 30 feet (and perhaps as much as 50 feet) from the bow of
any of neighboring boat when the wind is blowing hard enough to keep all
boats into the wind. Thus the length of our pennant could increase by 30
feet with no problem (at least until the wind dies). As to liability: 
With this scheme you'll bash one boat, but if your boat drifts merrily 
down the harbor you might be (un)lucky enough to bash several. Moreover, 
none of the nearby boats are terribly valuable (no Hinckleys, Swans, 
etc). 

re .2:

There are at least two types of these rubber snubbers. Type one has 
loops in both ends and is attached to the pennant or dock line or anchor 
rode by tying two overhand knots in the line -- such overhand knots 
reduce the strength of the line by 40% or so. Avoid this kind. Type two 
is the other kind -- the line is makes a couple of wiggles at each end 
of the stick-like snubber and is then wrapped around the snubber a few 
times. This type is only available for up to 5/8" line. As Gene points 
out, they only allow a couple of feet of stretch, but anything is better 
than nothing.

1045.4Shock absorber...MANTIS::FACHONMon Nov 14 1988 17:5717
    How about using a giant spring like the kind used on a cable-type 
    dog run.  The barrel of the spring has two U-shaped rods running 
    through it -- one in either direction -- with the closed ends 
    emerging at both ends of the spring, and the open ends bent over 
    at each end of the spring to grip it firmly.  When you pull
    on the U-ends you compress the spring.
    
    Use automotive strength/size material (marine grade) and 
    normal loading would likely stress the spring very little, but 
    extreme loads would absorb a lot of shock.  Have teflon "vertebrae"
    to protect the spring in the event of violent 100% compression,
    and fit the entire thing in an aluminum sleeve.  Use the spring on 
    the steel pennant.  To reduce chafing, use a large radius bow roller 
    for leading the nylon pennant.  
    
    Of course, nothing will help you if the pennants are just too short.

1045.5How about a PAD EYEUNIVSE::BAHLINMon Nov 14 1988 20:0233
    I bought a used boat and the owners mooring and anchor rodes were
    all suitable for the Queen Mary (1" nylon, three strand).  I mentioned
    this to him and got the standard words about 'bigger is better,
    etc.'.   Too much is as bad as too little.   This stuff stretches
    (in 10' anyway) about as much as your headstay [ 0 ]!
    
    I'm down sizing as soon as possible.  It doesn't fit the cleats
    or chocks as they were designed.  It is extremely hard to handle
    and therefore probably gets more abuse than a proper size.  Worse,
    it probably doesn't get used in marginal situations because of the
    inconvenience (and we all know that these are the situations that
    'blow up').   It only has one advantage that I can think of and
    that is that it lets you get lazy about chafing gear!
    
    Has anyone ever thought about mooring with a big pad eye on the
    stem?   The only reason we even need chafing gear is that we insist on 
    using deck cleats.   I know it might be a little embarassing to
    have your vessel look like a dinghy but if you could devise a
    convenient coupling method you could completely eliminate the source
    of chafe.   The stem is probably a lot more rugged than the deck
    as well.
    
    Maybe with this method you could have a conventional painter to
    a cleat (for easy pick up) and a safety tether to a pad eye which
    you could attach from your dink on the way home.
    
    
    Also a variant of Alan's idea..... use multiple tethers of
    progressively stronger and longer dimensions.   2-3 should do it.
    
    Another approach could be a bridle such that the boat rode directly
    head to wind in a blow.  Would this appreciably decrease the stress?

1045.6Alan's rightCADSYS::SCHUMANNMon Nov 14 1988 20:2921
I think it would be interesting to know how many of the mooring failures
were caused by a combination of storm and high tide. 

I suspect that many of the boats that broke their pennants could have
been saved by an extra 5 or 10 feet of pennant. When the weather is severe
enough, the chain and pennant will act much like an anchor rode that has
very short scope. The mooring buoy is dragged under, and the pennant
must take up much of the wave height through its own elongation. (The
buoyancy of the mooring buoy will take up some slack during the
troughs.)

If a 20' pennant is used instead of 10', then the pennant will be able to
withstand approximately twice the wave height under these conditions.

As Alan suggests, a "normal" primary pennant, with a longer secondary
pennant, seems like a good approach. Also, if both pennants are equally hefty,
the secondary pennant system will not start chafing until the first one
has failed.

--RS

1045.7Too late for usAKOV12::DJOHNSTONMon Nov 14 1988 20:4828
    Well this is a subject near and dear to my heart.
    
    1.) The mooring pennants on our boat were too short and we asked
    to increase the length.  The "gentleman" who was the harbor master
    (those of you familiar with him know what I'm talking about) refused
    our request to lengthen due to swing regulations.  He just got asked
    to leave, so that part is moot.
    
    2.) The cable just plain broke.  The chafing tube which runs the
    entire length was perfect and the cable was broken inside of it.
    
    3.) The chafing gear we had on our nylon pennant pulled off in the
    violent motion.  It was the kind with a slit tube and leather thongs
    at both ends.
    
    4.) Three of the four boats lost were in the outer row.  I believe
    that is no place for a boat to be moored.  Again, the harbor master
    disagreed.
    
    5.) Our cleats held just fine.  That was not the failure point.
    
    6.) We've heard a lot about how that was just too late in the year
    to keep a boat in the water for.  We had lots of company.  The boat
    was scheduled to come out that Wednesday.  Moorings should be able
    to handle that kind of stress.
    
    Dave

1045.8Some Newburport PerspectivesSALEM::MCWILLIAMSTue Nov 15 1988 11:3031
    Some interesting things learned this year in Newburyport;
    
    1. Everybody in our club was having problems with the three strand
       nylon pennants untwisting by the end of the year. We had several
       instances of pennants breaking because the pennant untwisted.
       The strands snapped one by one as the load became applied unequally.
    
       This phenomenon was new this year, and it was posited that it
       was due to the increased wake action in the river, and the higher
       river levels we had this year. The recommendation for next year
       will be to go to braid.
    
    2. Several dual pennant systems (i.e. both pennants run down to the
       top swivel) failed this year because the pennants wrapped around
       each other so tightly that the wrap lay against the bow edge
       which sawed/chafed through one/both of the pennants.
    
       This was posited to be due to the number and stength of the tidal
       changes causing the pennants to wrap before the swivel could
       untwist the dual pennant system. There still is no recommendation
       as to whether one should have a dual or single pennant system.
    
    In the October storms we also had several instances of chafe through on
    the pennants, but the end of the year is always a dangerous time for
    mooring systems. You have a full season's wear on the tackle, people
    are not down as often during the week/weekends, and the weather is
    generally much more severe. If chafe starts, there is nobody there to
    notice it.
    
    /jim 

1045.9keep an eye on your pennantHAVOC::GREENTue Nov 15 1988 12:3021
    The 3 strand unwrapping problem is not unique to Newburyport.
    
    I installed a new pennant when Steel Strings went into the water May
    15.  June 10, while home recovering from a minor operation, I had
    a call from the club asking me to come by at the earliest opportunity
    to retrieve her from Jubilee YC up the river about a
    mile.
    
    After fighting off the medication to a level where I could think
    with some clarity, I enlisted a good friend to take care
    of the problem.
    
    It turns out that the combination of new nylon and the consistant
    turning of the vessel around and around the mooring bouy untwisted the 
    eyesplice, freeing the boat and leaving the thimble on the shackle.
    
    Prevention?  Install a swivel on the mooring chain ( a notion initially
    rejected by the club mooring chairman when I installed the mooring).
    
    

1045.10My thoughts so farUNIVSE::BAHLINTue Nov 15 1988 13:2545
    I seem to recall (Chapmans maybe) reading that swivels were a no
    no on three strand for anchoring.   Come to think of it though everyone
    seems to use them on a mooring.  What's the difference?  I suppose
    a mooring is subject to lengthy stays and a typical 'anchoring'
    is temporary.  Does anyone have the 'why' behind this?  Also, if
    you use braid does the recommendation change?
    
    While on the subject of braid, I think another advantage is that
    it has more abrasion resistance.  The down side though is that it
    also conceals internal damage pretty well.
    
    Another point of significance here is that all synthetics are attacked
    by UV.  A season of exposure on your deck is probably good for 20-30%
    strength reduction.  I placed a note in the climbing notes file
    (150) asking about ways to go aloft from a climbers perspective.
    While there I saw another note (140???) about line.  One thing I
    remember from that was a recommendation that any line subjected
    to a 'fall' (presumably a large shock load) should be retired
    immediately.  The implication for sailors is that a single severe
    storm with the shock loads to a painter must severly weaken the
    line.

    
    Finally, another 'Chapmans tidbit', a round turn reduces line strength
    to 70% of nominal.  Any one have a number for the reduction at a
    chock?  My guess is that the combination of Round turn (at the cleat),
    'chock angle', UV exposure, possible multiple shocks in multiple
    seasons, and chafe take your nominal strength down dramatically
    by the end of a season.
    
    My thinking so far leans to something like this ........
    chain equal to mean high water plus ????? (expected surge height,
    and I haven't fixed this yet).  This would terminate at the float
    in a swivel.  The other end of the float would get two painters.
    The 'working' painter would be 10' to the chock plus enough to get
    a splice to a cleat.  This painter should be sized for winds to
    50 knots.   A second painter would be up one size from the other
    painter, 15 feet long and spliced both ends.  This painter would
    be shackled to a pad eye in the stem.  Also, both painters should
    be covered ( haven't figured this out yet ) and new each season.
    
    With a do it yourself splice or four you probably are talking about
    $25.00 tops, per year; cheap cheap insurance (and splicing practice
    too ).

1045.11Some more random repliesSALEM::MCWILLIAMSTue Nov 15 1988 14:4227
    Re: .9
    
    Untwisting of the eye splice could probably be prevented by whipping
    the end of the splice, and the throat of the splice, which tends to be
    common practice where we are.
    
    We are having problems with the rope actually becoming 'unlaid', the
    three strands separating so the pennant becomes a mass of three lines.
    With the twisting about one of the lines ends up taking the entire
    strain of the mooring, eventually failing leaving two stands, ... then
    one strand ... then you get a call from the Harbor Master calling you
    to retrive your boat. Some folks have been whipping the 3 strand nylon
    at intervals to prevent the untwisting but this seems to cause the
    pennant to become very twisted/hockled as it seems to captivate the
    strain the rope receives. 
    
    Re: .10
    
    The chairperson of our mooring committe doesn't like swivels either. I
    think the main reason is that swivels are inherently weak, and must be
    of a very large/expensive size to be as strong as the rest of the
    mooring system. We are thinking of trying swivels on our mooring
    system next year, but if we do we will opt for the next larger size
    than our 'light' chain. 
    
    /jim 

1045.12"Not just any port in a storm"PLANET::SCHLEGELTue Nov 15 1988 15:0440
    Well, what the hell!! Everyone else is giving their opinions, here
    goes mine!  First of all, mooring at the entrance to Marblehead
    Harbor is impossible in any storm because of wave action as the
    waves approach Marblehead and the limited room to swing (therefore,
    limited ability to increase scope).  Second, even further in Marblehead
    is almost impossible in a Northeaster. Just before the June 6th
    storm  about four years ago, I had just put two 3/4 inch new nylon
    pennannts on as a bridle, with additional chafing gear on each.
    I checked the boat before dark.  At 5:30 am, I received a call that
    my 32 footerwas laying on its side, fortunately, on the only stretch
    of sand next to Cloutman's yard.  I might also mention that my pennants
    go over a pretty good sized bow roller.
    About 20 years ago, I was sitting in Avalon harbor when we got hit
    with a Santa-Anna, in a 28 footer.  The reason I knew when the
    Santa-Anna hit was that I was dumped completely out of my bunk! 
    I got the job of wrapping the one inch nylon pennant with chafing gear
    between the 20 foot waves rolling through the harbor, while others
    fitted up storm sails.  Just as we hauled our ashes out of there,
    I was able to get a glimpse of 6 or 7 forty footers (or thereabouts)
    going backwards into the Avalon rocks. In about one half hour we
    had cut through half of the one inch nylon pennant.
    O.K., what's the moral?  In a storm, if you are stck out in it,
    stay off-shore.  If you are at a mooring, do the best you can with
    chain, wire or nylons (as several others have just been describing),
    or, since I like the boat I have, I make the time to haul it the
    hell out of exposed harbors like Marblehead when I know a MAJOR
    storm or Hurricane is still a day away. What do you have to lose?  You
    get in an partial day of sailing! So we use up one of our vacation
    days.  Can you think of a better use?  
    P.S. I am currently using two stainless steel pennants over my chain
    which is as long as the Harbormaster permits. Also, if you are not
    sure of your cleats, go back to your mast.  We have had to do that with
    the Chris we had, occasionally, when towing, and nothing on their deck
    was strong enough.
    
    deck was strong enough.
     
    
    

1045.13What let go??UNIVSE::BAHLINTue Nov 15 1988 15:3617
    re: .12  Marblehead incident you describe
    
    What let go in his incident?  Was it penant chafe?  What kind of
    chafing gear do you use?  How does 3/4 inch fit in your cleat/chock
    combo?
    
    I have seldom seen a pleasure boat with cleats and/or chocks designed
    for line this large.  I suspect that what happens (among other things)
    is that the 3/4 stuff gets far too tight a radius applied to it
    under storm induced stress.
    
    Think about your sheet blocks.  They are something like 3" in
    diameter for a 3/8 or 1/2 inch sheet.   This reduces friction but
    the radius is also crucial to  relieve stress/wear.   On a cleat
    we think nothing of putting 3/4 around a cleat that might be 3/4"
    in diameter where the line will be radiused.  

1045.14Rock sailing?AKOV12::DJOHNSTONTue Nov 15 1988 15:3812
    Re .10  Climbing lines are completely different than mooring lines.
    They are made to stretch a tremendous amount, thus absorbing the
    shock of a fall.  The lines are rated by falls. For example, the
    more "falls" the line is rated for, the better and more expensive
    the line.  One of our crew rock climbs and brought a beat up line
    on board once.  We were messing around and it somehow got hung up
    where we hang our changing sheet.  Well...you guessed it.  We accidently
    used it.  Funny as hell. The grinders just kept grinding and the
    trimmers kept cursing.  Never did break though.
    
    Dave

1045.15$.02 + $.02 + $.02 ...CDR::SPENCERJohn SpencerTue Nov 15 1988 16:2658
Several thoughts:

Bridles often don't keep head-to-wind or prevent boat swing, due to the 
wave action and wind shifts.  To me, a bridle is just a two-line system, 
but not any guarantee of easier motion.  Unless you have a cat or tri.

RE: .12 and others, a roller or chock is a nice idea, and works fine while 
the pull is downward.  But most chafe in the area of the roller occurs at 
the time of extreme yaw both P and S.  That's when the load is usually 
highest, and the rode is bent at the sharpest angle -- usually around a 
non-rollered (and sometimes sharp) edge.

RE: .7, perhaps your cable broke inside the PVC covering because of the 
internal chafe referred to in an earlier reply.  That never occurred to me 
as being a possibility before.

RE: .8, twisted line failure, I think .11 is on the right track.  You can 
buy nylon rode that varies quite a bit in how hard a lay it has.  My 
grandfather, who never lost a boat in a storm (including the Hurricane of 
'38, he was proud to point out), always reminded me to use the hardest lay 
line (it was all manila back then) on my mooring, and splice it *very* 
tightly, with proper seizings, and that way it wouldn't unlay under 
stress.  The advantage of twisted is that it does stretch further without 
permanent damage than braided; tables showing percentage elongation under 
load will demonstrate that.

RE: .10, climbing rope (kernmantel) is quite different from both twisted 
and braided construction.  Inside that colorful braided cover is a 
collection of fibers running longitudinally without twist.  As a result, 
the fibers themselves take all the shock loading -- not the rope 
construction.  Since climbing rope is designed to break a long fall 
safely -- only once is enough -- theoretically your life is well worth 
buying a new rope, even at those high prices.  Twisted nylon will absorb 
much less total shock all at once, but will keep on taking a lesser amount 
without degrading substantially for a much longer time.

We had a samson post on Puffin, and it was marvelous -- no chance of 
breaking free.  And because it was in the eyes of the ship, the length of 
line to stretch between it and the roller or chock was manageable with 
chafing gear.  If you tie the right weight nylon from your mast, you may
be surprised to find out how many feet ride back and forth past the chock
(6'+ on a 40' sloop!)  Check the elongation tables again.

For the ultimate chafing gear, I use leather.  Heavy stuff, smooth 
outside, prepunched stitching holes, and soaked before installation to
stretch it and make it easier to handle.  By carefully stitching through 
the rode strands a bit, and wrinkled to shorten its length while under no
rode load, it will stay in place and stretch with the rode under load,
especially if your rode is not being asked to seek its limits of
elasticity.  We used it on our mooring pennant, where in our case we
counted mostly upon ample chain down below (2.5 x MHW depth at Eastern Pt
YC) for shock loading relief, and used a 1" diameter hard-lay nylon. Great
stuff, and no problems...until in October 1983 the well-intentioned
dockboy rerouted the pennant around another chock outside the "leather
zone."  60 kt winds and 5' seas chafed through in less than an hour.

J.  

1045.16could 1 storm = 1 fallUNIVSE::BAHLINTue Nov 15 1988 16:4111
    I understand that [rock] rope and [marine] line are quite different
    in construction and certainly don't advocate throwing the painter
    away after a storm but consider this.   A storm like the one that
    hit in Early October was over 12 hours of sustained high wind and
    wave action (in Newburyport at least).  Conservatively this meant
    several thousand yanks on a painter which must fatigue something.
    
    Is there something to fatigue in nylon fiber?  Something invisible
    that makes the line cumulatively weaker (like what happens to metal
    fatigue)?

1045.17"Anyone for two short eye-spliced pennants?"PBA::SCHLEGELTue Nov 15 1988 19:4911
    re:13 Marblehead  incident
    
    At that time, I was using a heavy duty (about 1/4 inch thick) tubing
    over the nylon.  Who is thinking about a Northeaster that early!!
    The edges of the roller supports cut the tubing and nylon due to the
    wild yawing of the boat.  One of the 3/4 inch pennants normally laid
    over the other, the second one took over until it too was cut through. (No
    chocks, straight over the bow). I used to put one eye splice over
    the port and the other over the starb'd cleats which are pretty
    rugged.

1045.18More $.02SSVAX::SAVIERSThu Nov 17 1988 00:4030
    re .15 & .16
    
    Fatigue IS a problem with nylon and an engineer I talked with at
    New England Ropes recommended replacement of any mooring pennant
    after severe storm cycling. 
    
    I agree with .15. Leather chafe gear is the ONLY way to go.  Various
    rubber and vinyl chafe tubes will be cut through by nylon rope under
    high tension.  I've also seen nylon and rubber bow rollers cut thru
    to the shaft bolt by the nylon mooring pennant.  Rollers should
    be free wheeling brass or stainless. re .n where the stretch between
    cleat and roller can be FEET!
    
    Hard lay 3 strand also seems important and I've yet to see a discount
    store house brand as good as New England's.  They make it in different
    degress of "hardness" so shop for the best.
    
    As for the "ultimate" mooring system:  Use a primary 3 strand hard
    lay nylon pennant as long as possible, leather chafe gear, swivel,
    and heavy chain to keep the boat over the mooring in calm weather.
     I've never used a backup, but chain, shackled to the stem, to a
    point below keel depth of neighboring boats, then nylon to absorb
    shock (MINIMUM size to provide the strength needed, chafe is not
    an issue) to a swivel might be a good way to go.  The chain can't
    be chafed and the nylon absorbs the shock and the whole thing stays
    out of the way of the primary pennant.  The secondary should be
    longer, but remember that if sized right the nylon will stretch
    more than 40%.  Anybody ever tried it?
    

1045.19Let em SinkASABET::HOThu Nov 17 1988 21:4426
    
    Sounds like we're between a rock and a hard place.  If my chocks
    are are not smooth all around, the pennant chafes.  If the chocks
    are smooth, the pennant saws through the chocks.  If I tie off at
    the mast, the anti-chafe sleeve slides past the chocks leaving
    unprotected rope to abrade.  If I tie off at the bow cleat, there
    is insufficient elasticity in the pennant.  It sounding to me like
    there is no solution in desparate conditions that can be trusted
    to leave the boat undamaged.  
    
    Maybe it's the better part of valor to deliberately accept a lesser
    amount of damage as the cost of avoiding a total loss.  Alan's idea
    about the coil follows this line of reasoning.  Use the best primary
    pennant that practicality allows.  Then back it up with 50 - 100
    or more feet of anchor rode coiled on the deck.  When the primary
    breaks, the anchor rode plays out and the extra scope absorbs the
    storm surge.  If you hit a few boats on the way, that's what insurance
    is for.  Broken stanchions and above the waterline holes are still
    cheaper than losing the whole boat.  Sometimes the only way to save
    a boat may be to sink it with the intention of salvaging it after
    the storm.  I've read accounts of owners blowing holes in their
    hulls with shotguns to keep their boats off the rocks.  Storms can
    be like elections - somtimes  all the choices are bad.
    
    - gene

1045.20SMURF::ROBINSONSay a prayer and call a meeting.Fri Nov 18 1988 14:388
    
    I don't agree with the statement that "if you hit a few boats on
    the way, that's what insurance is for."  Insurance does _not_ give
    me the right to take actions that I know will cause damage to someone
    else's property.  It is not right to limit your damage by sharing
    it among your neighbors.
    

1045.21a flameMSCSSE::BERENSAlan BerensFri Nov 18 1988 16:3318
re .20:

In one sense you are right. In another sense your attitude saddens me.
It is just another example of the all too common selfish and
self-centered behavior in today's society. Many, many people have
invested much of their lives both financially and emotionally in their
boat. I, for one, have invested hundreds of hours and thousands of
dollars during the last ten years in improving my boat and have spent
untold hours sailing it and living aboard. I would be willing to allow a
few thousand dollars of damage to my boat (paid for by insurance and
perhaps even if not) if doing so meant that someone else's treasured
boat could survive instead of being destroyed. I have found most sailors
willing to help one another in times good and bad. I have helped others
and have been helped in return. It is one of the really good things
about being a sailor. 

Alan 

1045.22SMURF::ROBINSONSay a prayer and call a meeting.Fri Nov 18 1988 19:0718
    
    I'm sorry that my attitude saddens you.  However, I cannot see
    how saying that one does not have the right to lessen his own
    loss by inflicting a portion of it on someone else is either
    selfish or self-centered.  Causing someone else harm to 
    protect your own investment _is_ selfish and self-centered.
    
    It is generous of you to say that you would rather see several
    thousand dollars worth of damage to your own vessel than have 
    someone else lose his.  I am _not_ accusing you of selfishness.
    But I do not believe you have the right to assume that because 
    you are willing to accept such a loss, that everyone else is 
    also.  Respect for other people's property and responsibility
    for your own actions go hand in hand here, and they dictate that
    you cannot subject someone else to harm without their consent.
    I do not believe that mooring in the same area implies consent.
      

1045.23On the other hand...NSSG::BUDZINSKIJust when you least expect it... The unexpected!Fri Nov 18 1988 19:399
    I'd take the chance that the boat behind mine on short scope would
    have already, or will shortly part her pennant  and go ashore while
    mine bobs happily in her place.  Maybe several levels of backup
    are in order, the first just short of interference, the second longer.
    My feeling is that I would like to see all boats stay in the water
    even if they bump together some.  There is no telling what will
    bump what in a big storm and a boat drifting through a lot of others
    will cause a lot of dammage too.

1045.24MSCSSE::BERENSAlan BerensFri Nov 18 1988 19:5430
re .22:

Ah, nothing like a good argument to enliven an otherwise dull day!

Let me propose the following scenario: You are anchored off a rocky
island in Maine upwind of another boat whose owners and/or crew are
ashore. A strong late afternoon squall hits and you start to drag your
anchor, heading for the rocks. When you start your engine, a stray jib
sheet fouls the propeller. You now have a choice: Either attempt to
somehow tie alongside the boat downwind of you (which will undoubtedly
cause some minor damage to that boat) or allow your boat to be severely
damaged or destroyed on the rocks. If you truly believe what you wrote,
you will allow your boat to be damaged or destroyed, and you will take
every possible action to avoid damaging the downwind boat as you go by.
What would you really do? 

Actually, I quite agree with you, but only up to a point. One should
respect the property of others and do no one's property or well being
harm. Yet there comes a time when this respect becomes less important
than other considerations. What if, in my hypothetical situation above,
you have a one year old child on board your boat? Would that change your 
decision? Or, further, would your respect for the property and
well-being of others prevent you from calling MAYDAY if you were sinking 
during a storm? I somewhat doubt the average young Coast Guard lad would
really voluntarily rather come to your aid. More likely his commanding 
officer is going to insist. 

Also, and here I am uncertain, isn't there a law that requires you to 
help other sailors in distress? 

1045.25flames X 2ASABET::HOFri Nov 18 1988 20:4030
    
    Like I said, in extreme circumstances, the choices are all bad.
    Of course, no boat owner has any "right" to expect anything from
    his mooring neighbor.  But under sufficiently desparate circumstances,
    I probably wouldn't care.  The alternative that has the lowest loss
    potential for myself is the one I'd be inclined to follow.  If it's
    cheaper to pay for minor damage to my neighbors boat than to absorb
    the cost of a total loss of my own boat, then I'm probably going
    to damage my neighbors boat.  The dollar cost and ill will from
    the invevitable law suit is already factored into the decision.
    
    I personally own a cheap boat and don't intend to use the adjoining
    C&C44 as a expensive bumper.  But If my neighbor's boat were headed
    for the rocks and could be saved at the cost of damaging mine, he'd
    be a fool not to take the opportunity.  Of course, I would expect
    restitution.
    
    It may be pleasing to think that if my neighbor loses his boat,
    it's his problem.  But if we both buy insurance, that independance
    is an illusion.  We'll both pay higher rates.  It's the collective
    loss record that determines premiums.  The question the next M'hd
    harbormaster will have to ask is whether he should promote regulations
    that allow for a smaller number of large losses or larger number
    of smaller losses.  Even if the collective loss may be lower with
    many small claims, most people are probably going to assume that
    it can't happen to them.  Maybe he should simply regulate against
    storms between the months of April through November.
    
    - gene

1045.26There isn't one answerCDR::SPENCERJohn SpencerSat Nov 19 1988 02:4535
RE: .19,
    
>>>    Sounds like we're between a rock and a hard place.  If my chocks
>>>    are are not smooth all around, the pennant chafes.  If the chocks
>>>    are smooth, the pennant saws through the chocks.  If I tie off at
>>>    the mast, the anti-chafe sleeve slides past the chocks leaving
>>>    unprotected rope to abrade.  If I tie off at the bow cleat, there
>>>    is insufficient elasticity in the pennant.  It sounding to me like
>>>    there is no solution in desparate conditions that can be trusted
>>>    to leave the boat undamaged.  
    
Every boat owner faces an interrelated set of context-dependent choices.  
Key factors include your boat's design and construction; fittings and 
their attachment; rode type, size and condition; harbor shape, exposure, 
depth, bottom and mooring policy/pattern; tide state and expected storm
surge; wind direction and speed; anticipated storm track and duration; 
the list could go on.

There are better choices and worse ones; one has to plan each item as part 
of an interacting system.  I've learned a great deal by rowing around a 
harbor after a major storm, looking closely at the boats which survived 
and trying to figure out why -- it's most often the most well thought-out
system, not just the strongest or "best" components.  

The one rule of thumb, I guess, is that no one solution is best for everyone, 
or even for every storm.  Which is why there's a never-ending debate.


>>>    Storms can be like elections - somtimes  all the choices are bad.
    
But some choices are better than others.  (Even if you feel the recent 
election belies this fact ;-].)

J.

1045.27"Urban" vs. "Rural" Attitude ...MPGS::BAILEYBtoo much of everything is just enuffTue Nov 22 1988 11:3552
    RE .20 & .22
    
    I won't say that your attitude saddens me, or even surprises me.  It's
    typically urban American. "I got mine, you got yours, leave mine alone". 
    And in a sense, you are right.  
    
    However, maybe we all should take a lesson from the rural folks, who 
    tend to pitch in and help each other out in times of distress and 
    disaster without a real serious thought for the fact that doing so 
    may put themselves in danger or jeopardize their property.  I guess 
    it all boils down to priorities.   What's more important, your property 
    or the well being of your neighbors.  In urban society it tends to be 
    the former, in rural society the latter.  
    
    I think that we "week-end sailors" tend to switch from one attitude to
    another as we enter or leave the mooring area.  Out there we want to
    believe that we're "in it together".  Back on the mooring, it's "every
    man for himself" because we can assume that if our neighbor gets in
    trouble, well, "somebody" will save the day and it doesn't have to be
    me.  Unfortunately this isn't always the case.  And if your neighbor's
    boat parts his pennant you're just as likely to get clobbered as his
    boat goes by on it's way to destruction. 
    
    Maybe all it would take in this particular case is making sure you 
    have a similar mooring system as your neighbor.  Chances are if his 
    pennant parts, yours will too.  If he has a longer back-up pennant, you
    should too.  So should the guy next to you on the other side, etc.
    
    RE .24
    
    Alan, I'm not sure I follow your scenario as it applies to the base
    note.  In the scenario, lives are endangered.  And clearly the priority
    has nothing to do with property damage.  In this case anyone in their 
    right mind would do whatever is necessary to prevent injury or death to
    those on board.  However, what's this got to do with moored boats
    riding out a storm in a crowded harbor?  Nobody in their right mind
    would choose to ride it out on board.  And if they did, well they will
    probably find out that "survival of the fittest" is all about.
    
    I've never heard of that law you mentioned.  However, if a fellow human
    were in danger and I could do something to help (either on land or sea),
    I know what I'd do.  And I wouldn't need a law to tell me to do it.  I
    think most people feel that way, whether they're sailors or not.  I do
    not agree with your statement about the Coast Guard.  If they knew you
    were in danger, I doubt it would take a command from a superior officer
    to get them to act.
    
    I agree with the concept of multiple pennants, each successively longer
    than the last (by about 10' maybe).  Four or five ought to do it.
    
    ... Bob 

1045.28MSCSSE::BERENSAlan BerensTue Nov 22 1988 11:589
re .27:

My scenario in .24 is simply carrying the argument in .22 to an extreme. 
I way saying that, at some point and under some conditions, the concept 
that one should not damage the property of others (stated without any 
qualifications in .22) to save one's own property becomes one no 
reasonable person would continue to follow.


1045.29spare the philosophy - back to originalBRUTUS::BAHLINWed Nov 23 1988 11:5954
    I don't think we have exhausted all of the possibilities for a SECURE
    mooring design.  With a good design, all of the recent discussion
    is mute!  Can we get back on the original subject?  
    
    Another unexplored area is the potential pros and cons of multiple
    blocks.  i.e.  it should be possible to devise multiple anchoring
    (120 degree blocks on the circumference of a circle) such that the
    'rigid' center of these blocks can effectively be brought towards
    the surface by three chains joined at a central ring/penant point.
    
    This should have the following pros:
    
    	Length of 'stretchy' penant can be increased without increasing
    	turning circle - better shock absorbtion
    
    	Inherent 'backup' of primary holding medium, the chain.
    
    	Reduced angle of penant lead coming out of chock since you would
    	be attached to the 'surface' not the bottom - less chafe
    
    	All moorings could be brought to the same 'anchor elevation'
    	thus equalizing the required turning circles independent of
    	bottom variation (this one is stretching it)

    Cons:
    
    	More complex
    
    	requires co-ordination of entire basin to be successful

    	Could create hazard with many chains not going straight down
    	and no clue to chain direction can be implied from boat penant
    

    Any body have some thoughts on this?
    
    In another area entirely.  Does anyone have information on the
    following:
    	
    	Rules of thumb for stretch for various grades/materials of line?
    	All I have found is 'relative' tables that don't give any
    	quantitative data at all.
    
    	Rules of thumb for minimum radius of round turn for given radius
    	of line that will not significantly degrade strength?  All I
    	have found here is the shell length for turning blocks.  This
    	is suggested at 8 times the line diameter but I suspect a round
    	turn (for holding) is different than a line through a block.
    
    That's it but enough already on the philosophical question.  It's
    interesting but should/could be another note entirely.  Let's figure
    out a way to maximize prevention so that the philosophical question
    does not come up!

1045.30Triple Redundancy ?CECV03::WARDROPWed Nov 23 1988 14:4413
    re .29 
    
    Of course all three blocks and chains would have to be the size
    needed to secure the boat alone, since at any time only one would
    bear the strain.  Also, the float would have to be three times the
    size to carry the load, maybe more depending on scope.

    The weak points, of course would be where they are joined at the
    float and any swivel.  The triple redundancy should prevent any
    damage from mooring and chain failures, but I gather that isn't
    a major source of failures now.
    

1045.31some useful calculationsMSCSSE::BERENSAlan BerensWed Nov 23 1988 20:1372
re .29:

Yes, what you suggest will reduce the swinging radius of the moored 
boats. And what will happen then? More boats will be crowded into the
same mooring area, resulting in an even worse situation than there is
now. 

Other than that, your suggestion will triple the cost of a mooring 
(three times the equipment, three times the service required) which I, 
for one, would oppose.

re ropes and cleats:

Using a large line on a smallish cleat will reduce the strength of the 
line, but not enough to matter. Consider the following: My mooring has a 
1/2" bottom chain and a 3/8" top chain. 3/8" proof coil chain breaks at 
a load of about 5300 pounds and 1/2" chain at a load of about 9000 
pounds. 1" diameter nylon (my pennant) breaks at something over 28500 
pounds. I don't think that most mooring systems will fail due to the 
nylon pennant breaking (assuming it doesn't fail from chafing). 
Something else will break first. Pennants are much larger than they need 
to be from a strength perspective so that even a badly chafed pennant 
will be strong enough.

The elasticity of nylon rope is usually given as percent stretch for a 
given load, where the load is a certain percentage of the breaking 
strength of the rope. From this it is easy to calculate the stretch for
any load on a given rope (this is assuming that stretch is a linear
function of load which is more or less true). 

Let P = percent stretch at a given test load T (in pounds) -- the test 
        load is usually some fraction F of the breaking strength B (in 
        pounds) of the rope
    W = actual load (in pounds)
    L0 = length of rope (in feet) with no load
    L = length of rope (in feet) under load

    P = 100*((L-L0)/L0)     where P is given by the manufacturer

The assumption that stretch is linear gives

    L = L0 + c*W*L0     where c is a constant
      = L0 * (1+c*W)

Using W = F*B, these two equations can be combined to give the value of 
the constant c and finally:

    L =  (1+P/(100*F*B)) * L0     for any load and any length rope and 
                                  P, F, and B are given by the manufacturer

For example, New England Ropes three-strand nylon stretches 16.5% at a load
equal to 15% of its breaking strength. Thus, under a load of 1000 pounds, 
a 20 foot long, 1" diameter three-strand nylon pennant will stretch to a 
length of about 20.77 feet. That is, it will stretch about 9 inches. 
This isn't much stretch to absorb a quite significant load. A 2000 pound 
load will stretch the pennant about 18 inches. This makes it clear why 
big waves in a mooring area can create tremendous loads on cleats, 
mooring chains, and pennants. 

By contrast, a 500 pound load on a 1/2" diameter three-strand nylon 
anchor rode 300 feet long will stretch the rode some 22 feet. (This 
implies that it might be possible to anchor safely with such a rode 
in seas of 20' or so.) A similar nylon braid rode will stretch only
about 8 feet. (Nylon braid only stretches about 6.5% at a load equal to
15% of its breaking strength). 

These calculations clearly indicate that the loading on ground tackle, 
cleats, etc, is greatly reduced by using more elastic pennants/rodes. 
The safe working load on nylon rope is usually taken to be 20% of its 
breaking strength (1500 pounds for 1/2" three-strand and 1660 pounds for 
1/2" braid).

1045.32What me worry?BRUTUS::BAHLINMon Nov 28 1988 16:5520
    More turning circle should not lead to more boats (hypothetically).
    The intent would be to allow for more stretch under severe conditions.
    
    For example if we use 1" three strand on a 10 foot penant we don't
    get much advantage from stretch.  By using multiple blocks you might be
    able to get a 20' penant thus reducing the shock loading by a factor
    of ?? since you have doubled the stretch (stopping distance).
    
    I suspect that most boats could withstand damn near anything with
    1/2" line if a.) you had the room to stretch and b.) you had zero
    chafe.
    
    The suggestion in .29 was not intended to provide (primarily) a
    backup for the chain portion of the tackle.  Rather it is intended
    to reduce shock loading which in turn reduces the required strength
    in all components of the system (or increases safety margin).
    
    As for cost, it would still be cheaper than exercising my 10% 
    deductible :^).

1045.33a slight correctionMSCSSE::BERENSAlan BerensMon Nov 28 1988 17:3022
re .31:

I just noticed a slight error ..... the length of a rope under load 
is (approximately):

  L =  (1+P*W/(100*F*B)) * L0   

for any load W and any length rope L0 where P, F, and B are given by
the manufacturer. 


re .32:

The problem is that any reasonable length pennant on a mooring is just 
too short to reduce the shock loads on the mooring, etc, due to wave 
action. Even a 1/2" three-strand nylon pennant isn't elastic enough. 
A 20' 1/2" three-strand nylon pennant will only stretch about 4.4 feet 
under a 1500 pound load. Waves larger than this do, unfortunately, occur 
in mooring areas. The more I think about this, the more I think that the 
space constraints in most harbors simply make moorings safe in gale or 
storm conditions impossible. 

1045.34it's only property damageCADSYS::SCHUMANNSay NO to bugsMon Nov 28 1988 18:3821
It's interesting to note that *most* moored boats in the harbor did *not*
let go, and survived the storm intact. This suggests that the local mooring
standards might be adequate (or close to it). To reduce the carnage,
improvements in moorings would need to be applied to a high percentage of the
boats. The increased cost for ALL the moored boats must be weighed against
the damage to the boats that let go.

Of the boats that let go, some fraction let go due to negligence, some let
go due to conditions beyond the capabilities of the mooring equipment. Only
the latter class of failures could be reduced by fancier moorings.

Although the penalty for failure is high (you lose your boat), it is not
nearly as high as it can be for other boating failures, where you or your
loved ones can lose their lives.

Mooring safety needs to be kept in perspective: The oak tree in your front
yard can be blown over in a storm. Do you worry about parking your BMW
under it on a stormy night?

--RS

1045.35Wooden boat not equal to BMW :^)BRUTWO::BAHLINMon Nov 28 1988 19:2914
    re: .34   BMW is just a hunk of steel not a thing of beauty :^)
    
    I have a wooden boat.  It gets a lot of care.   Most of the care
    is devoted to repairing the hull after encounters with uncrewed
    BMW (ugly plastic) boats that break loose from their 'driveways' and ram
    into mine.  This season it suffered three minor and one major encounters
    of this kind.
    
    Could it be that plastic boats break loose because they are 'just
    BMWs'.   The most prudent protection for my boat would be a plastic
    detecting mine, attached to my mooring float.  Sigh, U.S.C.G. would
    probably not approve of this though.   Second best solution is to
    seek, through knowledge, ways to keep all boats 'at home'!

1045.36Wood is good, but glass kicks a--AKOV12::DJOHNSTONMon Nov 28 1988 20:3323
    Re .34  "Most" boats in the outer line of the harbor did NOT remain
    on their moorings.  Three out of five of us got trashed.  By sheer
    coincidence our mooring was checked that previous afternoon by The
    owner of Brown's Yacht Yard as he was passing by.  Just a friendly
    gesture knowing that foul weather was coming.  Looked good to him.
    
    The only boats that did not break free were smaller (less than 30').
    I am starting to follow Alan's belief that it may not be feasible
    to design a mooring that is safe in all conditions and yet provides
    a reasonable amount of space in the harbor.
    
    Re .35  So, you think that all fiberglass boats are a nuisance and
    that only wooden boat owners spend any time caring for their vessels.
    Get real.  I'm sure your boat is beautiful and you have a lot of
    pride in it.  We essentially rebuilt Fat Tuesday and had a great
    deal of ourselves invested in it.  Every boat suffers minor damage
    at moorings from collisions and lobster pots that are dropped too
    close to the boat.  The implication that owners of non wooden boats
    are inherently less concerned or careful in their mooring habits
    is just insulting.  I think the dry rot has spread beyond the boat.
    
    Dave

1045.37Say what ??MPGS::BAILEYBtoo much of everything is just enuffTue Nov 29 1988 11:1612
    RE .35
    
    Thought you wanted to "spare the philosophy" (.29).  Why then provoke
    it?
    
    I see no inherent advantage to mooring a wooden boat vs. a fiberglass
    one.  It's a matter of materials and care, with a touch of Luck thrown
    in.  If your neighbors are so careless that your boat gets hit four
    times in a season, then perhaps you should find a safer neighborhood.
    
    ... Bob

1045.38sorry noteBRUTWO::BAHLINTue Nov 29 1988 16:4111
    Sigh again..... Sorry if I offended, I thought the smily faces would
    be a clue to major leg pulling.   Plastic boats are in the majority
    EVERYWHERE so it only figures that you get hit most by plastic.
    
    And yeh it's sort of a rathole but .34 implies that this whole topic
    is one and I suppose I was over reacting to that implication.  I
    would probably have a plastic boat myself if I could afford a good
    one but I still would place plastique on my float for plastic control.
    
    Again, sorry for any offense.

1045.39CHEFS::GOUGHPPete Gough @REOThu Dec 01 1988 06:4316
    In October of 87 a Hurrican hit the Channel Coasts of Northern France
    and South UK. Over 1200 boats were lost or severely damaged. The
    marina in Cherbourg (Inside two breakwaters....) was destroyed.
    Many owners who had taken the trouble to chain their yachts to the
    buoys had their yachts sunk by "runaways". A fifty foot Swan lifted
    the pontoon it was alongside 6 feet out of the water as it heeled
    over. The conclusion of the RYA (Royal Yachting Association) was
    that in extreme weather, provided you have chained with a snubber
    fitted, is to check your insurance or if you get enough warning
    to get the craft ashore. However it should be said that many craft
    ashore were moved several hundred yards by the wind...... The force
    of the storm destroyed many trees and it will take several hundred
    years before the landscape if ever recovers to its former beauty.
                      
     

1045.40BPOV04::KEENANPaul Keenan 297-7332Thu Dec 01 1988 17:077
    On the subject of backup penants, how about running the backup penants
    through the bow chocks and cleating them at the stern. This way
    the boats LOA contributes to penant stretch without increasing
    the scope.
     
    On the down side, chafe protection would need some thought.

1045.41blocks on mast???BRUTWO::BAHLINFri Dec 02 1988 18:3012
    Hmmmm..... .40 is good, really good except for the chafe problem.
    You get 2-4 times the penant length without increasing your mooring
    circle an inch.
    
    The chafe thing here is equally nasty though.  I've got one really
    crazy solution that I hesitate to submit but what the .......
    
    How about snatch block/s a slight way up your mast, enough to keep
    the lines from touching anything on the way to the stern?  
    
    No, I didn't say that did I?

1045.42another ideaMSCSSE::BERENSAlan BerensFri Dec 02 1988 19:3216
Yet another idea .....

One of the major causes of chafe is, I suspect, the yawing of the boat 
around the mooring pennant. Plus, when the boat is at an angle to the 
wind (and thus usually at an angle to the waves), the load on the 
mooring system is increased significantly. So, if the boat could be kept 
headed into the wind ..... and this can be easily done.

Our boat usually wanders around an anchor rode at least 30 degrees to
either side of the wind direction. Last summer we made a 40 sq ft riding
sail that is hanked onto the backstay. With this riding sail, the boat 
wandered less than 5 degrees to either side of the wind direction in a 
30 to 40 knot wind. (This made being at anchor much more pleasant, by the 
way.) This indicates that a riding sail might increase the security of a 
mooring in heavy winds.

1045.43ASABET::HOFri Dec 02 1988 20:3213
    re .41
    
    I think you're on to something.  But why stop at the stern.  Put
    some more snatch blocks in at the corners of the boat and make a
    complete circuit of the deck.  In fact, why not keep going.  Instead of ordinary
    snatch blocks, use multi-sheave fiddle blocks and make several circuits
    around the deck.  Subject to frictional losses, we could have all
    the scope we want all neatly contained within the overall length
    of the boat.  All that rode on deck might even keep some of those
    pesky seagulls off.  8^)
    
    - gene 

1045.44Lots fo forceAHOUSE::GREISTMon Dec 05 1988 17:0619
re .43

Be careful of the loads you generate at the multiple fiddle block attachment
points.  If you take your mooring line from a bow chock thru a sheave at the
mast and back to a cleat at the bow, the load on the sheave attachment point
on the mast is twice the force on the line.  You WILL get more line length
and therefore more stretch to reduce shock loads.  

This extra line length is not exactly the same as more scope.  Extra scope
will reduce the angle between the mooring line and the water as well as 
providing the extra stretch.  This allows an easier motion of the boat
and actually reduces the forces on the mooring line.  

Lots of discussion on anchoring and the forces generated in an earlier note.
Worth going back and rereading.  It is note # 373.

Al


1045.45Moorings breaking looseCIMNET::LEBLANCMon Aug 12 1991 12:1418
1045.46good chafe gear a mustHPSRAD::HOWARTHMon Aug 12 1991 13:2028
re:  .45
Don,

I can't address the particular conditions that led to mooring 
failures in your area but I can give personal experiences.

Several years ago I kept my Hunter 30 at Wessagussett Yacht Club 
in Weymouth. The mooring location was exposed to everything from 
the northeast and I can remember 5 foot chop during storms. I 
don't recall any moorings slipping (all were mushroom types) but 
I do remember boats breaking free. In each case, the mooring 
lines chafed through and parted at the deck. The usual cause was 
inadequate chafe gear.

I almost lost my boat in a storm although I had what I presumed to be 
adequate chafe gear on the mooring line. The top my deck where 
the chocks are located broke under the strain of the line and 
sawed through 2 of the 3 line strands. I had thought the bow of 
the deck top was metal but no, it was fiberglass. I have since 
replaced it with a custom made, 1/8" stainless steel plate. I 
also added a 1/2" stainless steel bow eye so that I could attach 
a safety line with a snap hook.

In general, I believe the best way to attach a mooring line is 
through a bow roller rather than through chocks. I also recommend 
a second line for safety.

Joe
1045.47and it also knocked down a major willow tree....ICS::R_GREENRon Green 223-8956Mon Aug 12 1991 13:3231
    I was at the Willows Saturday _afternoon_, after the rain stopped and the
    sun had come out.  Beautiful sail for about 2 hours.
    
    The next morning, the launch operator called to tell me my boat, still
    on the mooring tackle, had gotten tangled with a neighbor and he had
    towed it to the dock - so what do I want to do with it.
    
    Turns out that there had been a tremendous storm/squall through Saturday
    morning - reports (wink, wink, nudge, nudge) of waves from the east  up
    to 12', or was it 15', through the mooring area.  Well, anyway, they
    were 8' or so.  Winds up to 45k. verified by anomomometer at the club. 
    
    Folks were talking about the number of mushrooms that had been moved around
    by the combination of high tide, storm surge, wave action and wind. 
    One boat up on the rocks east from Jubilee.  Sounded like a total loss.
    
    My mushroom was one of the victims - despite a 3.5x1 scope, extra
    weight and a mucky bottom.  Must have moved 75' with the storm.  Damn
    lucky (only word available) it didn't go any further.  I didn't
    notice it at all after my sail as neighbor must have been away.  As
    a result of the shifting around in what had be thought to be a solid
    mooring, I will be putting down a concrete block this afternoon as a 
    replacement.   The club had been requiring new members to put down the
    blocks rather than mushrooms because of previous problems.
    
    Winter Island and the Willows is open to this sort of storm.  Be
    advised that heavy tackle is better than light, frequent inspection is
    better than indifference, and a good insurance carrier is a good
    idea....
    
    Ron
1045.48use large braided nylon pennantsMSCSSE::BERENSAlan BerensMon Aug 12 1991 15:5821
re .45 and later:

I also subscribe to the theory that chafe is the most common cause of
boats leaving moorings unexpectedly. A 1/2" pennant can chafe through 
surprisingly quickly. A 1" pennant has four times the cross-sectional 
area of a 1/2" pennant and thus should take at least four times a long
to chafe through. Chafe is caused by the pennant moving across a fixed
surface (like a fairlead). The greater the load on the pennant, the
greater the chafe. Since 3-strand 1/2" nylon is quite elastic (stretches
under load), it will elongate (move) quite a bit under the varying load
caused by wind and waves. Braided nylon rope is much less elastic than
3-strand nylon rope. For a given, load, a 1" braided nylon pennant will
stretch about 1/10 as much as a 1/2" 3-strand nylon pennant and hence will
chafe much less. We have two 1" pennants on our mooring with smooth and
well-rounded on the boat. Even after the September 1987 hurricane there
was no noticeable chafe on our pennants. I'd certainly suggest using 
heavy braided nylon pennents on your mooring. More expensive, yes, but a 
lot more secure. 

Alan

1045.49Neptune's evil errand boy: ChafeSELECT::SPENCERMon Aug 12 1991 16:0923
re: .45,

IMHO, the major culprit:  Chafe.

If the stories are true, what do we hear most?  Some dragging (.47), but
that can be pretty much cured with Major Mooring Mass and proper
chain/rode/etc. Occasionally it's hardware breakage, but properly
installed eyes, cleats, bollards and samson posts don't fail more than
once in a blue moon and the 50-year storm that accompanies it. 

Otherwise, it's mostly chafe, and chafe can be a clever thief.  PUFFIN
(33', 11 tons) went ashore in less than 2 hours of short 4-6' chop and 30
kt winds because a *brand-new* 1" nylon pennant led over a roller on the
bowsprit got hooked on a chock, resulting in a not-quite-fair lead, and
frayed right through.  And we almost lost her years before when slewing
back and forth on the mooring over a 3-week period caused the rubber
chafing gear and line to nearly wear through by chafing on the sides of
the roller at the limits of the side-to-side excursion. So design
(engineering), implementation (construction & quality) and execution
(knowledgeable use) of ground tackle are just as important as holding
power and breaking strengths. 

J.
1045.50Don't underestimate marine growth.DDSEE4::CORCORANMon Aug 12 1991 17:3220
Chafe certainly rates number one as the cause of broken pennants, but don't
forget marine growth.  I always use double pennants, purchased new every
season.  But some warm summers in Salem Harbor I've had to replace lines
mid-season because of heavy marine growth.  It used to be that you could poison
your lines, but no more..., ecology and all that.

Another problem in crowded harbors is high tides.  Violent storms often bring
tides much higher that usual.  In a crowded harbor there's a limit to scope
you can put out.  A real high tide will drag any mooring, and that puts a
hell of a strain on your lines.  Also, if another boat cuts loose it can
foul in your lines and bring an incredible amount of strain (not to mention
crashing and bashing).  

During hurricane Hugo I put a bridle around my cabin.  I'm glad I did because
I lost some deck hardware from the side-to-side horsing my boat did.  My lines
jumped out of their chocks and cleared my fore deck for me.  I think my main
deck cleat would have held on it's own, but I'm happy it didn't have to.

In the end, despite all you do, some boats are lost each year.  As the old
saying goes; "The sea just doesn't care!"
1045.51Yes, the surge can get you!AKOCOA::DJOHNSTONMon Aug 12 1991 18:3413
    Re: -.1  High Tides
    
    High tides and storm surge is what brought the demise of my boat, Fat
    Tuesday.  Marblehead is a very crowded harbor with relatively short
    scopes allowed.  When a severe Noreaster hit we were on the outermost
    row of moorings exposed the most to the high waves.  The pressure
    simply snapped the braided pennant (can't remeber how big, but at least
    1 1/2 inches) as well as our steel storm cable.  Didn't break at the
    deck level, but halfway between the boat and the mooring!  The foredeck
    was located with the pennant and cable still attached with chafing gear
    in place.
    
    Dave
1045.52chaffing gear for a Catalina 22'?CIMNET::LEBLANCMon Aug 12 1991 19:1928
1045.53Bad Moorings Drag Neighborhood DownSTEREO::HOMon Aug 12 1991 20:4437
    re .52
    
    What purpose is served by the swivels?  It's not like the mooring float
    is a fixed object.  There are anywhere from 50 - 75' of chain underneath
    it which can absorb all the twisting that's likely to occur.  I doubt
    if much will occur.  The wind blows at random.  If it twists one way,
    it'll untwist the other way the next day.  In theory, if the wind
    clocks consistently in the same direction all the time and never
    subsides, the chain could twist and get short enough to suck your boat
    right under.  I would approach Mr. Zucco for a refund if that should
    occur.
    
    One thing which usually occurs to us when it's too late is to take
    careful note of the location of our mooring neighbors and the quality
    of their hardware, at least the peice you can see.  Private mooring
    owners, though bound by the same regs as the rental outfits, don't
    always comply and enforcement is an iffy thing.  If some of the mooring
    floats aroung you are not of the type offerred by the rental companies,
    watch out for location of the boat in a variety of wind conditions and
    move yours or have him move his if you're too close.  Be especially
    wary if the float looks like a Bliss Marine off-the-shelf special. 
    Who knows what it's attached to on the bottom.
    
    Harrier almost had a chance to file its first insurance claim this
    weekend when a small but heavy boat dragged its mooring right into the
    dock Harrier was tied to.  One of the owners went down to check it out
    just in time to fend off.  But he found himself awkwardly straddling
    the two boats unable to move with the smaller boat continuing to drag. 
    Several of us heard his calls for help and went over to secure the two
    boats.  In the fifteen minutes for us to do this the smaller boat
    dragged another 5'.  Ten more feet would have put it on the rocks.  The
    mooring float looked like a DIY'er.  I've had the same thing happen to
    my boat but I never got there in time.  When it come to moorings,
    discrimination is the way to go.  If they don't look right, put some
    distance between yourself and them.
    
    - gene 
1045.54Thanks!AKOCOA::DJOHNSTONTue Aug 13 1991 11:207
    Re: -.1
    
    Thanks Gene!  Denis just happened to go down to the dock in time to see
    the other boat dragging onto Harrier.  He really appreciated your help.
    We couldn't get the harbormaster to come and take a look!
    
    Dave
1045.55Keep your keel down while on a mooring.DDSEE4::CORCORANTue Aug 13 1991 11:5312
Swivels are most useful on tidal rivers where every change in tide swings
the boat around.  Of course this happens in a harbor too, but the narrow
confines of a river tend to make the swing more abrupt.  I really don't
know if swivels help all that much, and you have a good point, every additional
connection is an additional potential failure point.

Most authorities recommend leaving the keel down.  This tends to keep your
boat facing into the current instead of the wind.  I suppose if most of your
neighboring boats are power boats, you may want to keep the keel up, since
they tend to swing about with the wind more.  At any rate, be sure to crank
the keel up and down every now and then to keep the mechanism working and
free of fouling by marine growth.
1045.56Salem Mooring Inspections and Pennent LinesCIMNET::LEBLANCTue Aug 13 1991 12:1015
    
    Sam Zocco told me that the Salem Harbor Master will require all
    moorings to be inspected each year, starting this year. He didn't know
    what the penalty would be for not having your mooring inspected, but
    guested it would be the same as when it submerges below the surface due
    to marine growth; Zocco is instructed by the harbor master to remove
    those moorings from the harbor.
    
    I would like some opinions on a safe pennent size for a Catalina
    22' as well as whether chaffing gear is required for this particular
    boat as the cleats are right up on the bow. We're putting her in on
    Friday, weather permitting.
    
    Dan
    
1045.57Swivel to the left....MILKWY::WAGNERScottWed Aug 14 1991 14:5716
1045.58Salem Willows opts for blocksICS::R_GREENRon Green 223-8956Wed Aug 14 1991 15:4419
    re: .57
    
    without a swivel, there is a tendency to unlay 3 strand pennants or to
    put a real twist in braid.
    
    re:  .56
    
    Sam Zocco seems to be the mooring person of choice for Salem Willows. 
    Good reputation for honesty and delivery.  I bought the block from him
    last Monday night as he was installing 4 others in the immediate area. 
    
    SW went to an all block strategy last spring, with current mooring
    owners grandfathered until their gear wears out.  Based on the
    experiences of last weekend, we will not allow any mushrooms next year 
    ( if the current mooringchairman has his way) - the bottom is just too
    rocky and hard .  Mushrooms are great for mud where they can really dig
    in.
    
    Ron
1045.59WINTER ISLAND MOORINGMR3PST::OLSALT::DARROWThe wind is music to my earsWed Aug 14 1991 20:0131
RE .56 

Dan, we have an ODay 22 with the same hardware configuration and moor off 
Winter Island over by the power Station. 

There is a cleat on each side of the bow. The cleats are close to the edge of 
the deck with no room for chocks.  I use a Sam Zocco 2300lb block with the 
required chain. He did not supply the nylon pennant. My pennant is just over 
10 feet long and is a spliced 'Y' with the splice about midway from the shackle
to the eyes. The splice is about 12 inches long  and shows no signs of wear. 
The cleats are only big enough  for 1/2 inch line. The logic given me by Marine 
Speculator, the supplier of my pennant, was that the weak part of a pennant 
was the boat end where the chaffing occured. 

I place an eye over each cleat and then take my pickup bouy line from the eye
it is tied to, around the other cleat and back cleating it on the first cleat.
This has work well for last season and this.  Last season we started out by 
light house in the most exposed area where a severe squall took our mast down, 
but no problem with the mooring gear. Our boat has a fixed shoal draft keel
with a center board. I generally do not leave the centerboard down since 
I feel that the  any additional rolling will be cause less wear than the 
constant motion of the center board. 

The loss of the mast was due to over tightning a spreader fitting and the 
subsequent parting of the upper shroud at that point. No discount on my 
Boat US premium this year.

I will look for you this weekend. We are the only 22 foot boat with a blue 
dodger in the harbor.

Fred,  WINDSONG
1045.60Moorings during Bob, your input?BOMBE::ALLAThu Aug 22 1991 12:0437
     How about posting the performance of mooring during Hurricane Bob
    19 Aug 1991 ?
    
    Buzzards Bay, Pocasset- Barlows Landing, east side of the Bay.
    Mean high water at my mooring is 10 ft.   Bottom; mud.
    
    Storm surge est 8-9ft, harbor has limited exposure to the SW.
    
    Mooring type: concrete block, (2500 to 3500lb, can't remember if it
    was cast at 1 or 1 1/2 ft thick, 4 x 4ft)
    
    Bottom chain: 1" dia, 12ft long.   1" eye and eye swivel , top chain
    1/2" 15ft.    
    
    Mooring ball, 18" dia chain passes thru center.   Pennant; 1" nylon
    3 part spliced into bridle.   Chafe guard where it comes though the
    chocks is clear vinal tubing, slid on one piece before doing eye
    splices.   (extra 3/4" storm pennant to chain during storm, to cleat
    then to the mast)
    
    Thimble for pennant is stainless "plough" type (very deep, prevents
    chafe)
    
    Boat on mooring 28ft Pearson Triton, 8400# disp.   all sails and gear
    stripped.
    
    Mooring condition, good, split chafe guard on one side.  Believe it
    was due to a 25ft sail boat dragging thru the mooring area at height
    of storm and hanging up on my mooring pennant. (watched this during
    the storm at max surge, thought the boat was a gonner!)
    
    Motion of boat in storm was active but it never jerked to the end of
    the chain as I watched.     I give the 1" "battleship" chain credit
    the stuff must weigh about 10lb per foot.
    
    Most dragged mooring were mushrooms.    
    
1045.61InterestingSALEM::GILMANFri Jul 09 1993 19:2628
    Interesting discussion.... I read through it ALL.  I wonder why the
    only entry which brings up chain weight as a contributor to absorbing
    shock loads is .60.   If pennant lengths are so limited in crowded
    harbors then using much heavier chain would help make up for it as well
    as reducing the liklihood of chain breakage.  Although noone has
    mentioned chain breakage.  No one has had an underwater mooring fitting
    let go?  I was always taught that dead weight (unless we are talking
    about some SERIOUS weight) is a poor substitute for an adequately heavy
    mooring anchor..... such as a mushroom.  Of course if there is a rocky
    bottom a mushroom won't do any good.  My Dad used to use a 500 lb
    mushroom for his 35 foot crusier.  The boat never dragged even though
    there were some serious storms.  Since you guys are talking about
    blocks weighing many THOUSANDS of pounds I guess you ARE talking about
    serious weight.  None of those blocks dragged in those storms?  Can
    you pull a block easily for inspection of the mooring ring into the
    block?
    
         On my 17 foot boat (sorry... I don't have the dough some of you
    have) I have a 3/4 inch galvenized ring through the stem.  Chafing
    is not a problem from a ring in the stem the way it is over a chock
    or bow roller.  If you would put a ring through the stem (however
    'unsightly') you would eliminate your primary chafing sources.  Of
    course in the 'plastic' boats you would have to make sure your stem
    could take the load.
    
    Jeff
    
    
1045.62July or June issueOTOOA::MOWBRAYThis isn't a job its an AdventureTue Jul 13 1993 11:205
    The July issue of Cruising World has a good article on Anchoring ....
    not just the techniques but also the forces at play.  Through
    diagramming the force vectors on the boat/anchor system, I am convinced
    and am shortening my all chain rode to about 30' and using nylon. 
    
1045.63CHAINSALEM::GILMANWed Jul 14 1993 15:5111
    What about using the mooring chain to add dead weight to the mooring
    system?  The forces tending to drag the mooring block would also
    attempt to force the chain into being taut with no catenary.  A
    heavy chain would tend to sag and act as a shock absorber which there
    was alot of discussion on (shock absorbing systems) with limited
    scope possible.  Seems to me the chain would tend to SOLVE this
    problem!
    
    Yes, I know heavy chain is expensive... but so is your boat.
    
    Jeff
1045.64you can't be safe no matter what happens .....MASTR::BERENSAlan BerensWed Jul 14 1993 16:4739
re .63:

I would argue that heavier chain would make failure less likely, but not 
that it would SOLVE the problem.

First, harbor regulations limit the length of chain that may be used. 
The longer the chain, the larger the swinging circle and the fewer the 
boats that can be moored. 

Second, regardless of the length and size of chain, there will be some 
combination of wind, waves, and tide that will cause something to fail.

Carry your heavier chain is better to a logical extreme. Along comes a wave, 
which tries to push the bow up. Say this wave is 10 feet (not unlikely 
perhaps in a strong storm). If the chain is sufficiently heavy, the bow 
will be held down by the chain, and the wave will go over the boat, 
quite possibly with disastrous results. Or something on the boat will 
break as the bow submerges. My boat submerges about 1 inch per thousand 
pounds of load. The bow trims up/down a couple of inches between full 
(90 gallons -- 745 pounds) and empty watertanks (which are under the
V-berth). The force required to submerge the bow is obviously going to 
be very high.

With less heavy chain, there is still likely to be some combination of 
wind and waves that will bring the chain nearly taut. But the chain 
doesn't have to be taut for something to fail, such as the deck cleats 
(or whatever) to which the pennant is attached. There is some limit to 
the strength that can be built into the boat.

Sure, boats are expensive, but so are heavy mooring systems. I'm already 
using a heavier block and heavier chain than required by my harbor 
regulations. But realistically, there is no doubt a storm that will 
destroy my boat no matter what. The probability of such a storm 
happening is fairly remote (we've survived two or three hurricanes and 
other bad storms in the last 13 years). The overall safety of our boat 
is probably increased more by spending our limited funds on other than a 
still heavier mooring. 

Alan
1045.65When the next wave comes at "just" the wrong moment..ASDS::BURGESSWaiting for ZEUS to comeWed Jul 14 1993 17:3223
re               <<< Note 1045.64 by MASTR::BERENS "Alan Berens" >>>
>              -< you can't be safe no matter what happens ..... >-

	right, its a diminishing returns thing.....

	One thing that came to mind while reading your reply was,  

OK, about an inch per thousand pounds - but that's a static measure, I
wonder if there is a wave frequency that will send a boat into
oscillations such that the bow  WILL  go under, no matter what, even
with low applitude (or low energy ?) waves.  Obviously there is and
its likely to be different for each boat, its load, its load
distribution, etc.   Knowledge of this frequency could be useful if
one also knows the probability of such frequencies (and their
harmonics) at the mooring site and if one is able to configure the
mooring chain to NOT also resonate at that frequency - the goal would 
be to find a chain resonant frequency that is NOT sympathetic(pun ?) 
to the boat's frequency.  At this point I'm beginning to suspect that 
all this is elementary stuff to people who REALLY KNOW about storm 
moorings - I'll shut up and re-read all the other 60-odd replies.

	Reg

1045.66not likely?MASTR::BERENSAlan BerensWed Jul 14 1993 19:038
re .65:

Certainly resonant oscillations are possible, but probably not very 
likely. There is quite considerable damping in the system, wave trains
are usually not very regular in storms, and (I would think) that the
resonant frequency would depend on the angle between the boat and the
waves, an angle which is usually changing constantly.

1045.67ChainSALEM::GILMANWed Jul 14 1993 19:3118
    Yup, of course there is a cost/benefit trade off.  Much of the earlier
    discussion in this string revolved around methods to absorb shock loads
    with limited scope.  The discussion even involved using snatch blocks
    to rig even longer pennants the length of the boat to absorb shock from
    storm action.  Therefore, the use of heavier chain seemed to me to be
    a 'better' solution than some of the other alternatives because it
    'fixed' everything.  Using chain does not increase scope, does increase
    the ability of the mooring to withstand strain, and it does provide more
    give to shocks due to wave action because of the weight of the chain.
    
    If you use battleship anchor chain to moor a 30 ft yacht obviously your
    not going to move the chain much in foul weather thus the shock
    absorbing benefit is negated.  Obviously with battleship chain you
    would have to use a 'bell buoy' to hold it off the bottom and tie a
    pennant to it.  But not going to such extremes, heavier seems better to
    me.  You have to decide where your safety dollars are best spent.
    
    Jeff
1045.68Overbuilt seems to create it's own fatigueMILKWY::SAMPSONDriven by the windThu Jul 15 1993 11:5823
    	I don't own my own mooring, have never put one together so perhaps 
    I'm clueless when this is all said and done. But with heavier mooring
    chain, that chain is going to be working on itself all the time,
    whether there is a storm, a two foot sea or almost flat calm. Overbuilt
    systems seem to fail for what appears to be the work required to carry
    their own weight. As an example I think of '70 vintage automobiles,
    built like a tank, with what by todays standards are huge motors,
    considered long lived a 100K mi. Also, more in line with this file, 
    early Whitbread boats, I seem to remember accounts of many failures in 
    these super heavy boats, where the fatigue caused by carrying the extra
    weight resulted in rigging failures etc.. In more recent
    circumnavigation type races it's the light weight boats that are
    surviving. 
    	I can picture where an overbuilt mooring will have the chain near
    the surface constantly wearing on itself in an effort to support the 
    slack chain further down. So I would fear that on overbuilt system,
    wearing on itself all the time, will then be compromised that moment
    the big storm comes through. 
    
    Someone might be able to blast me to pieces on this, but it came to
    mind while reading these strings. 
    
    Geoff
1045.69HAEXLI::PMAIERThu Jul 15 1993 13:3718
    re -1:
    
    no, the chain is damaged at the bottom from constantly moving
    around.  
    
    My boat is on a mooring all year round in a mountain lake. The depth
    is around 120 feet and the chain is 16mm (1 inch is 25.2 mm ?)
    This mooring has to withstand at least twice a year winds in excess
    of 80 kn.
    
    The chain is so heavy, its impossible to have just one mooringboy. There
    is a second mooringboy submerged, 20 feet below the surface, to carry
    most of the weight. I'm using two nylon lines, each ca. 1 inch.
    I had no problems during the last 10 years, except that the bowsprit
    gets damaged in very strong wind, when the bowsprit hits the
    mooringboy.
    
    Peter
1045.70MASTR::BERENSAlan BerensThu Jul 15 1993 16:3619
re .68:

My understanding is that the fatigue life of a material is function of 
number of times a load is appplied (cycles) and stress, ie, the applied
load divided by the ultimate strength of the material. The more 
frequently the load is applied, and the higher the load, the sooner the 
failure.

In the examples you cite, the shorter life of older cars is more likely 
due to poorer materials, manufacturing, design, etc, rather than fatigue 
failure.

There has been published concern (eg, by the Gougeon Brothers) that 
lightly built boats, while initially strong, have quite short fatigue 
lives and that structural, riggings, etc, fatigue failures are much more 
likely as these boats age than in older, more conservatively built 
boats. 

Alan
1045.71FatigueSALEM::GILMANThu Jul 15 1993 19:5822
    Fatigue failure is based on a certain number of cycles as the standard.
    i.e. 100,000 cycles or some such number.
    
    Certain fittings (chain, bolts etc) will fail after a certain number of
    cycles which can be approximated STATISTICALLY.... UNLESS the system
    is overbuilt.  Disregarding corrosion or wear (we are talking fatigue
    ONLY) the failure point becomes INFINITE at a certain oversize size.
    What that size is depends on the type of fitting.  
    
    My point is that fittings, chain etc. don't AUTOMATICALLY fail due to
    fatigue alone if your running a large enough size.
    
    Wear and corrosion are another matter.
    
    If wear is working at oversize chain... then certainly wear is working
    at undersize or 'right' sized chain too.  There is more material to
    absorb the wear with oversize chain too.
    
    I don't buy the argument that heavy chain wears itself out due to
    weight therefore THATS why you shouldn't use it.
    
    Jeff
1045.72Cruising World's good adviceOTOOA::MOWBRAYThis isn't a job its an AdventureFri Jul 16 1993 11:5125
    With regard to the use of heavy chain, my understanding (based on
    observation and the C.W. article that I referenced earlier) is that if
    you use and entire (heavy) chain rode, that the resulting force at the
    anchor bitts is essentially downwards pulling the boat down in the
    waves (as Alan says) and the vector component that then holds the boat
    in position is a small fraction of the total force exerted by the
    mooring system.  Consequently in order to hold the boat there are
    massive "eaxtra" forces in play.
    
    It seems that the same effect is achieved by using a length of heavy
    chain next to the anchor (or mooring block) and then using nylon rope. 
    I have modified my ground tackle this year to 6 fathoms of chain
    (although it is only 1/2 inch which I would like to be 3 fathoms of
    3/4) and then either 200 feet of 5/8 nylon or 150 feet of 1 inch nylon. 
    The system will load up (theory is anyway), raise the chain from the
    bottom and then take some stretch out of the nylon.
    
    I'll let you know how it works in a week as I am off tonight for a week
    of Cruising around the abandoned communities in a bay called Trinity
    Bay.  You could tell that I had plans, the first sunshine that is
    predicted is for next Tuesday ...... rain and easterly winds (cold
    ones) from now to then ......  could we start a note on what it is like
    to sail in warm weather ?  Anyway, I guess I'll get to play with some
    whales and go to some of the most beautiful places in the world so
    whats a little rain ?
1045.73MOORINGSSALEM::GILMANFri Jul 16 1993 12:0020
    I wonder where YOU are?  Cold, wet?  Certainly not New England.
    
    Downward force vecter etc.....
    
    Thats what the buoy is for, to hold the weight of the chain.  THEN when
    a storm sets in the pull of the boat tends to straighten the chain out
    by pulling it up off the bottom, also tending to pull the buoy
    underwater.  Of course the buoy tries to float.  There is the shock
    absorbing system:  Heavy chain, buoy trying to float, and the stretch
    of the nylon.  No system is perfect, but this system seems to address
    the shock loading issue pretty well.
    
    If you had heavy chain ONLY without the buoy, then yes, I agree that
    much of the force would be tending to pull the bow down.  But we are 
    talking about MOORINGS with buoys... not anchoring with battleship
    anchor chain, right?
    
    Hope you had a fun safe trip.
    
    Jeff
1045.74MASTR::BERENSAlan BerensFri Jul 16 1993 12:4640
re .72:

I think that some of the analysis in the Cruising World article is 
wrong, but no matter.

I would disagree with your decision to use 5/8 or larger nylon rode. The 
larger the diameter of the nylon rode, the smaller the stretch for any 
given load. When anchoring, you want as much elasticity as possible to 
absorb shock loads and compensate for waves. I know I put an analysis of 
this in SAILING somewhere, possibly in Note 373. 1/2 diameter nylon rope 
has a safe working load of some 1700 pounds, which is certainly more 
than enough. The only advantage that I see to a larger diameter is more 
reserve should there be significant chafe on the rode. 

Our every day working rode is 40' of 5/16 chain and 300' of 1/2 inch 
three-strand nylon rode. We've never noticed any chafe on the nylon in 
all the times we've anchored in Maine and elsewhere. We used to use a 
shorter length of heavier chain, but found it very difficult to handle 
and stow. I now much prefer to use the same weight of chain by using a 
longer length of smaller chain. And besides, the gypsy on our windlass 
only accepts 5/16 inch chain. 

Which brings up another point ...... Heavy ground tackle is all well and 
good, but you do have to handle it safely. Being no longer as young and 
agile as I once was, I find that I use our windlass rather often in 
retrieving our ground tackle. Pulling a 35 lb CQR and 40' of chain 
(about 70 pounds total) aboard is difficult and hard on my back (and I 
now have to be even more careful about this). Lowering it is also not so
easy. 

Whatever you choose to do, there will be some compromises. I doubt that 
there is any single best solution or method (perhaps for a single, 
specific situation, but not in general). 

Anyway, have a good trip. 

Alan

PS Warm weather sailing has is drawbacks, like sunburn.

1045.75OverdesignSALEM::GILMANFri Jul 16 1993 15:3112
    Alan, I agree that 1700 lbs is a safe load capacity for normal
    conditions.  With a larger yacht and storm/wave anchoring or mooring
    conditions the INSTANTANEOUS loads can be beyond belief!  And 
    instantaneous loads snap line and chain as surely as loads of a longer
    duration.  Overdesign has its place, expecially in a marine
    environment.
    
    As you have said, excessively sized chain to handle a 'lunch hook' or 
    working anchor can cause its own set of problems.  But for a 'permanent
    mooring' I believe overdesign is usually appropriate.
    
    Jeff
1045.76MASTR::BERENSAlan BerensFri Jul 16 1993 16:3529
re .75:

I think that reply .72 had digressed into a discussion of anchoring, not 
mooring. I believe that what I said in .74 is appropriate for anchoring 
and was not intended to be a recommendation for moorings. 

As mentioned in a much earlier reply to this note, the breaking strength
of large nylon pennants is very high, something over 20 000 pounds for
1" braid. I seriously doubt that any foredeck and cleats (of the size
boats owned by SAILING participants) will withstand a 20 000 pound load
without failure. 

Sure, overbuilding is fine, but only up to a point (in my view). At some 
point the costs (financial and otherwise) become unreasonable compared
to the potential return on the investment. Each of us make our own 
judgments of what is appropriate for our boats. You might also, before 
being quite so emphatic in your recommendations, take into consideration 
that the expected wind and wave conditions vary considerably from 
mooring area to mooring area. A mooring that is perfectly adequate and 
safe in one place might well be totally inadequate in another (eg, the 
comments by Peter Maier vis a vis mountain lake mooring). 

The wind loads on a moored boat are surprisingly low -- about 500 pounds 
for my 32' boat in a 45 knot wind. The loads from waves can be very high 
indeed, which is why sheltering from waves is more important than 
sheltering from wind. The first few replies to this note make this 
quite clear.

Alan
1045.77Agreed, sort of, more or less.....ASDS::BURGESSWaiting for ZEUS to comeFri Jul 16 1993 16:5375
re                       <<< Note 1045.71 by SALEM::GILMAN >>>
>                                  -< Fatigue >-

>    Fatigue failure is based on a certain number of cycles as the standard.
>    i.e. 100,000 cycles or some such number.

	Yes, sort of - I believe that it is expressed as the number of 
cycles that the system can be expected to withstand at the working
load;  where "expected" is some mean value about which there is a
distribution. 

>    Certain fittings (chain, bolts etc) will fail after a certain number of
>    cycles which can be approximated STATISTICALLY.... UNLESS the system

	again, the number of cycles is some mean or average about 
which there is a distribution.

>    is overbuilt.  Disregarding corrosion or wear (we are talking fatigue

	Even when  SUBSTANTIALLY OVERBUILT  there is a finite limit to 
the number of cycles that can be endured before fatigue failure - 
granted it might be an extremely high number, but it IS finite.
There is also a finite probability of latent defects in material, 
"weakest link"  etc., however overbuilt systems are likely to be more 
tolerant to latent defects since there is a higher safety factor.

>    ONLY) the failure point becomes INFINITE at a certain oversize size.

	NO - just very high, very unlikely to fail...... 

>    What that size is depends on the type of fitting.  

	and application
    
>    My point is that fittings, chain etc. don't AUTOMATICALLY fail due to
>    fatigue alone if your running a large enough size.

	for a sufficiently small number of cycles
    
>    Wear and corrosion are another matter.

	but can't be ignored
    
>    If wear is working at oversize chain... then certainly wear is working
>    at undersize or 'right' sized chain too.  There is more material to
>    absorb the wear with oversize chain too.

	more margin, right.   Somehow I'd have to believe that there 
is enough allowance (margin ?) in the recommendations for "right 
sized" configurations.
    
>    I don't buy the argument that heavy chain wears itself out due to
>    weight therefore THATS why you shouldn't use it.

	neither do I, though right now I can't come up with a simple 
expression that shows you're right.  It just seems intuitive that a 
length of heavy chain hanging from a bouy and getting thrashed around 
in a storm and yanked on by a boat that wants to leave....  is going 
to have more strength left in it after n hours than a lighter chain 
would have; probably a LOT more, since it's weight is helping to 
restrict the movement.    
    
>    Jeff


re Alan,

	Yes, in practical terms - if enough is enough and a little
extra buys some peace of mind then go for it, just don't double up on
that and break your back. There are indeed other (perhaps better)
opportunities for the investment of every boat safety dollar. 

	Reg

	
1045.78Toy?SALEM::GILMANFri Jul 16 1993 17:1428
    I will 'bet' that virtually all the boats moored in any given harbor
    are using the 'recommended' size fittings or larger.  Do you agree?
    
    If a hard Northeaster hit virtually any exposed harbor in New England
    I will 'bet' that some boats would break free.  Do you agree?
    
    Given my first statement no boats 'should' break free UNLESS their
    moorings were underdesigned.  Even neglect should't matter much because
    neglect was 'built in' to the sizing of the orginal fittings, right?
    Fatigue and corrosion was 'built in' to the original design too.
    
    Obviously my arguments above are ridiculous.  We are living in the real
    world, an imperfect system.
    
    Exactly.
    
    Therefore you 'should' oversize your fittings but not to the point
    where its not cost effective or the equipment is unmanagable.
    
    Your points about infinte cycles etc. I understand.  By the word
    infinite I mean the life cycle is so long that for all practical
    purposes it can be considered infinite.
    
    Some of the toy deck fittings (cleats etc.) manufacturers (OEM) install
    on their boats make me laugh at their short sightedness, or optimism.
    (THIS boat will never see a bad anchorage therefore we can put in toy
    fittings).  Of course the reason is economy. Once the boat is sold its
    the owners problem to keep it safe in spite of the toy fittings.
1045.79Chafe & CorrosionMILKWY::WAGNERScottMon Jul 26 1993 17:1231
    
    	Some 2nd-degree stuff from Reality Land:
    
    	I like to talk to harbormasters about this sort of stuff. They are
    the first to see the boats on the beach or up the river, usually. And
    time and time again, it's chafe that cut pennants, not chain links
    failing. Even tiny, rusty old links! Amazing. Also, when swivels don't,
    chain kinks and rubs itself to death, on top of wrapping around
    mushroom posts and pulling bows down.
    
    	My system is heavy chain down low (1/2") and light up top (3/8").
    This is cuz the top chain is in an air-water mix, and is good for
    maybe 2 seasons, then is replaced. The bottom stuff is for shock AND
    keeping the boat sort of in one place. Our mooring committee tends to
    stuff `em in close. Not my choice! The bottom is silt/muck, and the
    depth doubles between high & low tides.
    
    	A new piece of 3/8ths beats a rusty 3/4ths every time! Overbuilding
    (which I agree with to a point) does not replace vigilance.
    
    	Scott.
    
    	PS Anchoring-wise: here's a tricky one. You want to let out lotsa
    scope in a blow. (Danforth anchor). The front boogies thru, wind does a
    180. The (nylon) rode catches the keel during the spin. Now the boat is
    athwart the wind, anchor basically locked! What a pain. My solution was
    to row the 2nd anchor out in the dinghy (bumps bruises OUCH) and try to
    get it to bury (grassy Nantucket bottom) then pull in enough to unload
    the first rode...
    	Anybody done anything up front that would have been easier? A
    sentinel would have required hundreds of pounds...
1045.80A vote for all chainGUIDUK::ROTHENBERGMon Jul 26 1993 19:0923
    
    Re -.1, PS:  If I understand your problem correctly, it can be dealt
    with (up front) using a nylon spring line attached to an all chain rode.  
    The heavy chain is not gonna foul much on your boat; the nylon spring
    will take care of shock absorption and reduce bow roller noises that chains
    make.
    
    Once you get into that situation, and depending on swinging room,
    remaining rode, and sea conditions, you might try letting out a bunch
    of rode all at once (make sure bitter end is secured!), hopping in the
    water to unfoul the keel, and then hauling things back in.  This gets
    pretty interesting if the boat is hobby-horsing much.  A mouthful of
    keel is tough to swallow.
    
    One of the more difficult lessons to learn about sailing (and cruising
    in particular) is that there is no substitute for vigilance.  Yeah,
    chain is heavier and more difficult to haul in, but it was always
    worth the additional peace of mind.  Of course, we still had to take
    when setting the anchor.  Heavy ground tackle and good anchoring
    technique always struck me as one of the better insurance policies
    available.
    
    Dave
1045.81small mushroomMASTR::BERENSAlan BerensMon Jul 26 1993 19:3812
re .79 and the PS:

We've found that a not terribly heavy weight (a 15 pound mushroom 
anchor) tied to our nylon anchor rode (about 10' from the bow which is 
twice our draft) is sufficient to pull the rode more or less straight
down as the rode goes slack and keep the rode from fouling on the
keel/rudder/propeller. 

Alan

PS This particular digression more properly belongs in Note 373, the anchoring 
note.
1045.82Sentinel TimeMILKWY::WAGNERScottTue Jul 27 1993 15:5413
    
    	Yup, sorry, wrong note. Once I get talkin'....
    
    	Anyway a sentinel is now on the shopping list. Aside from the
    decreased wrapping tendencies, a big bennie is the rode being below the
    propellors of dolts who have to test their drunken piloting skills by
    bouncing thru the fleet.
    
    	For the weight, a big hunk of lead with a shackle should do me-
    
    	Thanks for the inputs!
    
    	Scott_the_cross-noter
1045.83Everything you read in here is true!MCS873::KALINOWSKIFri Oct 14 1994 16:0226
    After a couple of weeks overseas, I had a chance to go out last Sunday.
    The boat next to mine (appx 24 ft daysailor) was not there. It was
    in the parking lot with a  snapped rudder.
    
    I asked about it yesterday. The yard worker says "did you look at the
    other side of the boat??". I walked over and it was ripped at the deck
    seam all the way down the starboard side and the aft section was beat
    up really bad. Evidently it was getting pummelled on the rocks when
    they found it. 
    
    The reason I bring this us is that there had been a nasty blow while I
    had been away. many of the boats with undersized pendents ended up on
    the rocks. In this case, the owner had decided against the marina
    supplied nylon pendent for his own setup, a 12 ft peice of 5/16's vynal
    covered wire with nicropressed thimbles on both ends. I can remember
    earlier in the  year telling the wife that setup couldn't take a shock
    load if it had to. Sometimes I hate being right.
    
    It is a sorry way for someone to learn a lesson. It looks like a total
    to me.
    
    
        john
    
    (who had wisely had the wife check our boat while gone and had found
    wraps of the pendent around the mooring float and corrected it).