[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

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

195.0. "Shopping for a Keel" by MOTHER::BLAISDELL () Tue Oct 22 1985 21:03

If you're shopping for a cruising boat then you're shopping for a keel.
I've heard stories and rumors and accusations about performance of different
keel configurations, but never had seen any hard data. An article, "Shoal Draft
Options" in Novemeber 1985 "Yacht Racing & Cruising" provided some and like the
info offered in Note 193 I thought you might be interested before you run out
and buy your new boat. Unfortunately data was not presented for full keel or
swing keel boats. 

The tables in the article speak for themselves so I will simply give you the
data and let you draw your own conclusions. I will say that the data is in the
same direction as I thought but the conventional shoal draft keel penalty is
more than I imagined. The author, John Marshall - Henry Hinckley
Co., recommends the keel/cb design. 

Before the tables, Scheel keel and wing keel descriptions are provided.
Also please note that the data is based on smooth water tank tests. Equivalent
data for rough water is not offered but a statement is made that the wing
keel design could be expected to suffer in rough conditions. 

Defs:  1. Sheel keel is a modified conventional shoal draft keel. It is 
          slightly bulbous its maximum depth in order to put more weight 
          lower down and also to reduce "tip-vortex formation"

       2. The wing keel in these tables is not like Australia II's keel, it
          is a cruising design and sweeps back rather than forward. The
          article points out that this solves the kelp collection problem
          but you still have a problem if you ground, ie you can't heel
          a wing keel yacht to reduce draft.


Table 1: Olympic Course Race Results

(speed difference in secs/mile vs shoal draft)

Wind         Scheel    Wing     Keel/     Fin 
Speed        Keel      Keel     CB        Keel

25 knots      3.7      11.2      8.7      21.1
15 knots      9.9      14.9     14.9      24.8


Table 2: Upwind Performance
                                                      Speed sec/mi faster
                                 Tack     Leeway     vs Shoal keel in wind
                       VMG       Angle      %         10 knots   15 knots
IOR (Fin) keel        5.36       85.7      115          43.4       47.3
Keel/centerboard      5.19       85.2      100          22.1       30.7
wing keel             5.17       87.2      155          21.0       28.0
Scheel keel           5.03       89.4      170           7.9        8.6
Shoal draft keel      4.97       92.4      165           0.0        0.0
         
          
Notes: 1. VMG = velocity made good in knots
       2. Tacking angle is measured in 10 knots true wind
       3. Leeway is measured as percentage of keel/cb leeway

- Bob       

T.RTitleUserPersonal
Name
DateLines
195.1GRAMPS::WCLARKFri Nov 22 1985 11:5439
I would like to offer an opinion on Scheel vs. fin for cruisers.

I own a Tartan 33 with a Scheel. This boat is a fractional rig.  The S & S 
design was also offered in a fin/Masthead rig configuration by Tartan and 
called the 33R. The 33 draws 4'6", the 33R draws 6'. Sail area is similar
but the 33R has the advantage once Genoas greater than 125% are bent on.

I have competed against 33R's and 33's for the last 2 seasons in a cruisers'
race at the annual Block Island Tartan 'Gathering of the Clan'. Most of these
boats are pretty stock and use Dacron sails (Mylars and Spinnakers are banned
for the 'race'). 

On a boat for boat basis I found the 33R can point slightly higher (maybe 2-3
degrees at the most) up wind, however my boat speed is slightly greater in
the same conditions with the advantage to my boat increasing as the wind
decreases. Off wind, without spinnaker I can easily pass the 33R. 

These differences cannot be explained simply by the keel since the rig also
is different and each has its own strengths and weaknesses. 

I have found it necessary to keep this boat on its feet, with heel under
25 degrees when close hauled. If she is allowed to heel further the leeway
increases dramatically. I have compaired Compass steered course to Loran-C
calculated CMG under both conditions and found that when under 25 degrees
she has less than 3 degrees leeway. If I allow her to heel past 25 degrees
for long the leeway goes up to 10+ degrees. The leeway does not appear to
increase with increased sea state.

The Scheel has a definate advantage over the fin where most of a cruisers
time is spent - on the hook. Only the centerboard is better in this regard.
Centerboard boats (board up) do not have the same righting moment as a fin or 
Scheel and will, on the same hull, not be as docile on the hook.

Now I know that no one aspect of a boat (contrary to what the Aussies were
quoting) is THE determining factor in a boats performance. Instead it is the
synergy of hundreds of design variables that makes it work + choosing the
product that most nearly matches an owners 'needs'. On the right hull, with
the right rig, and under the correct crusing conditions, a Scheel is super.

195.2PULSAR::BERENSFri Nov 22 1985 15:3416
I'm not sure what you mean in the paragraph about anchoring.

I would be a little concerned about the sudden increase in leeway when 
heeling past 25 degrees. I have been in a few situations where it was 
necessary to go to weather in a heavy wind and large sea. If we had had 
to reduce sail enough to keep the heel angle below 25 degrees, we would 
not have had enough sail up to drive through the waves. (Of course, this 
situation only occurs off a lee shore.) 

What are the mainsail areas of the 33 and 33R? Fractional rigs tend to 
have larger mains and thus be faster downwind than masthead rigs 
(assuming no spinnakers).

Alan


195.3SUMMIT::THOMASMon Nov 25 1985 12:0418
A couple comments:

We chartered a Sabre 38 this summer that had the same angle-of-heel:leeway
characteristics. In fact, the owner's manual made a point of not going past
25 degrees if you didn't want to make excessive leeway. I assumed then that
this was caused by the lateral profile changing at that point to be seriously 
out of balance with the rest of the forces on the boat. I make the same
assumption for the Tartan. My greatest surprise was in finding this sort
of thing on a Sparkman & Stephens cruising design!

Assuming that the Tartan is a moderate displacement boat, I wonder if the
problem would be as serious in high sea/wind situation for the Tartan as it
would be for a heavy displacement boat. The moderate displacement boat
should need less sail area to generate the necessary power to drive through
the seas.

Ed 

195.4PULSAR::BERENSMon Nov 25 1985 15:2722
Perhaps the sudden increase in leeway past a 25 degree heel with a
Scheel keel is due to the bulge at the bottom of the keel no longer
being effective in keeping water from flowing around the bottom of the
keel. The change in lateral area as the boat heels should be a fairly
smooth one. In any event, I think that this sudden increase in leeway is
quite undesireable. What if you are sailing in a gusty wind, with the
heel angle oscillating back and forth past 25 degrees, and you are
trying to keep a dead reckoning position? 

While I agree that a lighter boat needs less sail area to drive it when 
the sea is relatively smooth, a heavier boat has more momentum and may be 
less slowed by the impact of waves in rough conditions. I think that 
this funny behavior of a Scheel keel argues very, very strongly that it 
should only be used on a very stiff boat. If you are trying to make 
progess to windward in heavy weather, I should think it would be 
virtually impossible to always keep the heel less than 25 degrees. The 
Scheel keel may be fine for the good conditions we mostly sail in, 
however.

Alan


195.5CDR::FANEUFTue Nov 26 1985 16:3614
A note on going to windward in heavy weather:

An important factor is directional stability; the yawing motions of a boat
induced by wave action have a dramatic effect on the drive obtained from
the sails, especially as range of angle of attack for acceptable drive
narrows as the wind velocity increases. The momentum of a heavier boat
in a sea is important because it tends to affect directonal stability as
much (or more) than it tends to keep the boat driving. Lateral profile
also has an effect; shallower boats tend to move around more in a sea.
The effects interact; in crusing designs, there is some correlation between
heavier displacement and larger lateral plane.

Ross Faneuf

195.6GRAMPS::WCLARKWed Dec 04 1985 16:5032
The Tartan 33 displaces 10,000 dry (LWL - 28' 10"), the main is 300' and
the 125 is also 300'.  I have not been particularly concerned with keeping
her below 25 degrees because it seems very natural on this boat to do so.
I can carry 600' in apparant wind to about 20kts. I take a reef in the main
from 20-30kts, and a second reef in the main plus reducing the geneoa to about
95-100% with wind above 30 kts. When it really starts to howl I rollup the
Geneoa and go it with the main alone (reefed to about half - or the 2nd reef
point). I have sailed in these conditions (as a matter of fact all in one
day) on the Rhode Island Sound square waves. The above give me a boat which
stays up around 20 degrees heel maintains a slight weather helm and goes
to weather at hull speed. 

Of course sudden wind increases could lay the boat down, but first of all
the slight weather helm causes it to round up when the wind increases, which
maintains heel and boat speed. The amount of deviation is dependent upon
the increase and duration of the gust. Second, the Tartan is not a tender
boat for her displacement. The keel/displacement (44%) and concentration
of ballast low tend to give her a good righting arm. 

I guess I should put this in perspective a bit. The boat tends to sail best
on her feet. It is easy to keep her up with sail control. She telegraphs
her sail requirements thru the helm and gives warning, fairly early, that less
sail is needed. If sailing past 25 degrees she doesnt come apart, she just
increases leeway. My wife is a much better gauge of excess heel than the
heel indicator or the boat. Since we are not racers she prefers to walk on the 
cabin sole instead of the setee fronts when possible.   Finally, if I cruised
an area where wind and gusts were much more familiar to 40 than 10kts I would
have bought one of those heavy cruisers we pass all summer long. 
                 
Walt


195.7LSMVAX::MEIDELLWed Dec 18 1985 16:0712
re .6

25 degrees seems a little much for a fairly modern design. Actually, you
stated she sails better upright. Most modern designs do not like heels of
greater then about 15 degrees. On average you can expect 2 degrees of leeway
for every 8 to 10 degrees of heel. Some designs are better some much worse.

For those with older design styles (i.e. rounder hull forms), they are less
sensitive to heel and cen generally deal with 25 degrees of heel, some old
CCA designs (late 60's) actually sail well at 30 to 35 degrees heel.


195.8Pivoting KeelsSTOWOA::KALINOWSKIWed Jan 29 1997 15:4115
    Anyone been watching the new pivoting keels?  Peter Isler put one of
    these motor driven puppies on a 30' sailboat and proceeded to wax
    everyone until they caught on and he withdrew from the race.
    
    According to him, he can easily race with 4 crew, whereas on a normal
    boat, he would need 7-8 depending on wind conditions to keep the boat
    flat.  Downwind, the smaller size makes the boat go faster.
    The keel adjusts in just a second or so. Very quiet and quick. 
    
    At the dock, the boat bounced from one side to another like one of
    those lowrider cars in L.A.
    
    If they can make these keels reliable, it will be interesting to see
    who puts it on a 40-45 foot boat with roller main and headsail for true
    singlehanding of a larger sailboat. 
195.9UNIFIX::BERENSAlan BerensWed Jan 29 1997 19:1118
re .8:

>    Anyone been watching the new pivoting keels?  Peter Isler put one of
>    these motor driven puppies on a 30' sailboat and proceeded to wax
>    everyone until they caught on and he withdrew from the race.
    
Hmmm, can Isler spell "cheating"? It is always nice to hear of a 
famous person being an excellent role model for our children.

Cynical comments aside, I suspect that pivoting keels will:

  1. be more expensive than fixed keels,

  2. tend to be unreliable, certainly more so than fixed keels,

  3. seriously intrude on interior cabin space,

  4. and be used by racers and shunned by cruisers.
195.10Win at all costsACISS2::GELOWed Jan 29 1997 19:516
    Peter spells it "justwinbaby". I agree with Alan on all 4 points, but I
    like the idea of new concepts in our sport. How does this keel work? Is
    it similar to the retractable keel on a Melges? (lifts straight up)
    Where did you find out about this boat?
    
    Carl 
195.11STOWOA::KALINOWSKIWed Jan 29 1997 20:5012
    No, it pivots just inside the hull, and goes port or starboard, depending 
    which key on the remote control you hit.
    
    American Sailor and I think Sail did stories on it over the past year.
    Or you can watch Marine Voyager this week on Speedvision to see it in 
    action. Talk about dialing in the heel rate [roll the boat over in light
    airs, right her when the winds comes up]...
    
    I wouldnt' call it cheating either. I mean we all know it couldn't have
    a rating number without everyone knowing about it. I think Peter wanted
    to wax some folks and then say "look, it's the keel" just like our
    buddies in Perth did years ago.  
195.12motors are for landlubbers, and getting homeWRKSYS::SCHUMANNThu Jan 30 1997 00:187
If it has a motor, why not just apply the motor directly to propulsion?

If you wanna make this thing compatible with the spirit of the sport, it
needs to be flipped by winches, or maybe by water power!! Like the amplification
scheme used to make wind vanes work.

--RS, cruiser-at-heart, but known to race occasionally
195.13CIM::LORENLoren KonkusThu Jan 30 1997 11:072
    There are also pictures of the internal mechanisms on page 37 of this 
    month's Sailing World. 
195.14Traditional power - no problemDECC::CLAFLINDoug Claflin dtn 381-6355Thu Jan 30 1997 12:0916
Re .12)  If he was reducing drew from 7 or 8 to 4-, then it seems a
simple matter to dedicate some muscle power to pulling the sucker around.

I approve of the direction of pursueing innovation.  On the other hand, I
share Alans general sentiment about this particular one and its
practicality to non racers. 

Given my choice of keels (i.e. a bucket of money to modify Holiday II), I
would prbably go for a full keel with a modest center board.  Gives me a
good solid sailing boat with the board up, and better upwind performance
with the board down.

A final question, does this boat come with a chromed chain 12" steering
wheel and big fuzzy dice?

  
195.15Why not in a cruiser??MILKWY::MILKWY::SAMPSONDriven by the windThu Jan 30 1997 12:3517
I don't understand why a canting keel will not be popular in cruisers. I think
that's akin to saying that multihulls will never have a place as a cruising vessle.
I have doubts that modifications would be practicle in anything, but a device
designed into the boat seems quite reasonable. 
	The discussion of these in sailing world (actually they show two of the
Vendee Globe racers) point to advantages over water ballast. The advantages pointed
out are quicker taking and that the weight of the ballast is designed into the hull
form. The righting advantage is compared to having several dedicated rail meat type
crew parked on the rail. 
	Wouldn't a cruiser benefit from less heel on any given passage? Is it
acutally easier and more relaxing to make way for a day and a half with your rail in
the water? Do cruisers usually sail with a full compliment of crew or do they do
more short handed work?
	Most inovations I expect will be seen in the racing arena first, but I don't
see why this would be of no benefitt to cruisers.

Geoff
195.16UNIFIX::BERENSAlan BerensThu Jan 30 1997 14:0432
re .15:

No doubt some cruisers will choose a canting keel. I expect that a 
majority won't for several reasons:

1. A canting keel will obviously be much more expensive than a fixed 
   keel. There are many more poor sailors than rich ones.  

2. A canting keel will of necessity be of some additional mechanical
   complexity and will potentially need maintenance and repairs. This
   may not be an issue where well-equipped boatyards are available, but 
   may be very much a problem in other areas (ie, most of the world 
   outside the US and Europe).

3. A canting keel will almost certainly be more seriously damaged in a 
   hard grounding. What if the keel is jammed all the way to one side and 
   you are days of sailing from where repairs can be done? Not too safe.

4. Having to tack the keel adds to sailing complexity if done manually.
   If done electrically or hydraulically, see point 2. 

5. Safety is likely a concern, too. What if you get knocked down? How 
   will the boat behave? 

6. The canting mechanism is likely to take up much needed interior 
   space. 

Most cruisers I've met do sail with a small crew. Surveys show that 
the most common crew is two people, usually a man and woman. And they 
likely don't sail rail down -- they reef (I do). Many of the innovations 
of racing are useful in cruising, many aren't. 
195.17electronic control?WRKSYS::SCHUMANNThu Jan 30 1997 15:186
How about an active keel? Drive the keel motor from a feedback circuit 
that keeps the mast pointing straight up. Then you always have the hull
going through the water in the same configuration, which should result
in simpler constraints when designing the hull shape. 

--RS
195.18Maybe a matter of semantics involved hereDELNI::CARTERThu Jan 30 1997 16:1724
    I think part of the discussion involves a definition of "cruiser."
    
    A person who uses a sailboat in coastal sailing, but not racing, likely
    considers her/himself to be a cruiser.
    
    If we add the word "world" in front of cruiser, I suspect a lot of
    persons who disagree with Alan's expectation that "cruisers" are
    unlikey, as a whole, to embrace canting keels would tilt to agreeing
    with Alan.  From what I've read, and from the few world cruisers with
    whom I've spoken, world cruisers tend to be techno-wizardy-phobic.  When
    the only way to work on the bottom of a boat may be to careen against a
    bulkhead somewhere, fin keels tend to leave a lot to be desired
    relative to a longer keel.  Make the fin keel a movable one, and that
    configuration falls even lower on the "got to have" scale. 
    
    I'm a (coastal) cruiser, and I don't like moving object which are
    intended to be part of my ballast package.  Add to that the complexity
    of keeping a moving keel moving when, and only when I want it moving,
    and I sdon't think I'd be thrilled with having that appendage under my 
    hull.
    
    djc                
    
    
195.19Not today, but maybe tomorrowMILKWY::MILKWY::SAMPSONDriven by the windThu Jan 30 1997 16:3714
	Granted, it's not going to leap on the market today, and if it were
to, I wouldn't want it on my boat (then again I don't need it right now).
Personally I see a wear machanism that will need maintenance or be
dangerous. But as the system is refined I expect it will become more
popular. 

	As for how it will behave in a rollover I would expect it to be
quite the opposite of what I'm told is the danger in sailing a multihull. 

	Grounding isn't as problematic with a full keel as with a fin keel,
but there are a lot of fins sailing around. I have sailed on more fins than
full keels. 

Geoff
195.20Great ideas didn't stop with the Pina and Santa MariaSTOWOA::KALINOWSKIThu Jan 30 1997 17:0938
    A-symetric kites, motor driven winches, roller mains, Carbon Fibre
    sticks, low stretch halyards, high tech sails, that bizzare main/jib on a 
    rotating mast that Gary Hoyt has been ballyhooing. These all are starting 
    to show up on cruisers, usually the larger ones where 2 people sailing 
    really mean short handed (ie 38-50 + footers).
    
    As a coastal cruiser, think of a J-170 with many of these bells and
    whistles. Expensive, Sure, but so is a live-in crew.  With enough
    freeboard, even a power failure with the keel in one position could be coped
    with. To do 14-16 knts easily to get to protective shores before a 
    storm gets to you without having to push the boat so hard that there 
    is a good chance you will break something or get exhausted trying to get 
    the last .1 knt of speed. Or extending your range because the boat is
    30% faster means new horizons.
    
    Most crusiers put though-hulls in their boats. Why??  They could break!
    Lots of bad things can happen. It is a matter of engineering the system
    to make it safe. I saw a 75' sport fisherman (Ryovich or something)
    last night that had all the throughhulls in one panel in the boat. They
    entered a waterproof box so even if something went wrong with any of
    the openings or the peice of hull below them, the worst thing would be 
    having to work in 2 feet of sea water from above (the box had a hatch top)
    while the rest of the boat was intact. 
    
    People in big crusiers use centerboards in some cases. They could leak
    too. Same for water ballast, which even when it works takes up a lot of
    interior space, so you have to buy a larger boat ($$$$).
    
    How many folks do you know who have traded down to a small boat
    because they couldn't handle their big boat anymore. Tradition is nice,
    but even schooners have engines folks. Now most of us are still
    young enough to where we don't have a retirement check beging e-mailed
    to the bank for us, but our options are larger, while we are
    healthy.  For some, I think this will be a way to enjoy a larger boat
    further into one's golden years.  And by the time it is made completely
    safe, it may be time for you to retire and look at these features in
    your next boat.... 
    
195.21Gotta yank somebody's chainDECC::CLAFLINDoug Claflin dtn 381-6355Fri Jan 31 1997 12:1423
Any adjustable keel like this will undoubtably get into the mark,
probably in a cruiser/racer boat (i.e. cruising J baots) first.  I would
guess that racers will soon follow.

As for 10 - 15 knot trips expanding your horizon, I suggest the
MacGreogor 26.  Then you can go at 25-30 knots, pop your sail up just
before the new harbor and sail in.  We did this going into Portland two
years ago.  Motored through the slop, and sailed the last hour or so in
when there was finally some wind.  We looked great, new generation of 
Hiscocks complete with a three year old daughter on board.

In all honesty, some variation of this does make sense for some coastal
cruisers, just not me.  Winged keels were the previous killer app in hull
design.  While they are still out there, they are not as popular as a
couple of years ago.  Deep bulbed keels, moderate fins, skegs, planing
hulls, traditional hulls with full keels, swing keels and centerboards
all have their place.  After the initial excitement, their relative
market share probably indicates how well they meet the needs of the
boating public.

Meanwhile, back at the ranch Doug Claflin and the crew of Holiday II
have discovered the secret to getting the knot meter to read over 5 knots
(rotate the dial).
195.22Point the paddle wheel in the right directionGRANPA::KMAYESStarboard!Mon Feb 03 1997 13:3213
Doug,

>Meanwhile, back at the ranch Doug Claflin and the crew of Holiday II
>have discovered the secret to getting the knot meter to read over 5 knots
>(rotate the dial).

I was embarrassed to find when I hauled "Labyrinth" this winter that I had
installed the transducer backwards.  Could never get over 4.7 knots last
year!

Regards,
Keith