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Conference vicki::boats

Title:Powerboats
Notice:Introductions 2 /Classifieds 3 / '97 Ski Season 1267
Moderator:KWLITY::SUTER
Created:Thu May 12 1988
Last Modified:Wed Jun 04 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1275
Total number of notes:18109

374.0. "Boat leans to one side" by FREEBE::BMURRAY () Mon May 15 1989 13:34

    
    I recently purchased and old boat and motor. The boat is a 15 ft.
    MFG and the motor a 45 h.p Merc. Boat-1960  motor-1962
    The motor runs well. The boat has a strange problem:
    When I get close to wide open throttle the boat starts to slowly
    lean to one side (not always same side). When I compensate via
    steering the boat slowly starts to lean to the other side. The onle
    way to stop this is to back off on the throttle. It is a feeling
    of uncontrolability. The boat is a runabout style with a deep
    v hull. 
    Possibilities:
    1) Boat has had floor replaced-looks proffesional-could this cause
       weight unbalance? (people and gear in boat was balanced)
    2) Motor tourque/steering??
    3) Boat design-deep hull
    4) Someone said overpowered-the speedometer said 23 mph when this
    starts to happen-I have doubts about integrity of sppedometer- we
    were guessing about 30-35 mph. Boat runs well at 3/4 throttle.
    
    I only use the boat for freshwater fishing. I am satisfied with
    it now but would still like to find out why this happens. If 
    anyone can shed some light on this I'd really appreciate it.
    Thanks,
    	Bob
    
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374.1Well, here is next to no help.....!ARCHER::SUTERGentlemen, start your *marine* engines!Mon May 15 1989 15:1615
    re: Bob,
    
    	Are you sure the lean IS NOT there at lower speeds or is
    it just not as noticeable? Since you can compensate for the lean
    with the steering and it doesn't always lean the same way then
    I'd be inclined to say that it's just a characteristic of the
    boat/motor. Hey guys, would the wrong motor height cause this?
    
    	If the problem was caused by imperfections in the hull or
    torque of the motor then it would always lean the same way.
                                 
    	I also would find it tough to believe that 45hp is
    overpowering a 15 ft hull.
    
    Rick
374.2Water in the hull?BIZNIS::CADMUSMon May 15 1989 15:3316
374.3Might be normalSALEM::KLOTZMon May 15 1989 15:3519
    It seems possible that the boat is not made for the speed created
    by a wide open throttle (i.e. Perhaps it is overpowered)
    
    You said it seems to change sides -- 
    
    Bear in mind that a planning hull will list 'into' the wind (or
    current). Perhaps your feeling a normal reaction - if the wind hits
    you on the port - the boat will lean toward the port side.....
    
    It might just take some getting used to - when this occurs there
    is a tendency to 'oversteer' - now it leans the other way -
    this would cause that 'uncontrolable' sensation you mention.
    
    I'd suggest you just give it awhile - get used to it - before trying
    any fixes.  In the meantime back off the throttle a bit & enjoy
    it -- sounds like you like the boat & you still have plenty of speed.
                                          
    			Hope they bite,
                                        Lou "Phanta Sea"
374.4Yea, I am sortof a novice.FREEBE::BMURRAYMon May 15 1989 18:0412
    Wow you guys are fast! I really appreciate the advice. I did not
    mention that when we first got on the throttle a bit it ran poor
    and water came in the back a little. We adjusted the motor tilt
    two notches and it was a great inprovement. Maybe I need to find
    a happy medium here. The lean is definitly not there at lower speeds-
    it cruises beautiful. There is also a definite chance that I am
    not yet used to it yet. I am used to an 8' aluminum/5 h.p. cruiser.
    It's a great feeling to stand up or lean over without having the
    boat move. Thanks again and i'll post the "fix" here when/if I
    find it.
    Bob
    
374.5Hooked bottom?SICVAX::SCHEIBELU can Teach A new dog UL TRIXMon May 15 1989 18:1417
    I have two other possibilities. One is that the motor is a twenty inch
    shaft and the transom is cut for a fifteen. Just measure it with a
    ruler at the centerline of the boat and look for a 20 or 15 in the
    motor model number. The second is a bit more of a problem . You
    entioned that the floor was replaced. The boat may have what is called
    a hooked bottom. This happpens when a boat has foam floatation and the
    floor is replaced and it is nor refoamed correctly. The bottom of the
    baot in the rear caves in towards where the foam would be supporting it
    creating an inverted belly in the bottom . If this hook is far enough
    towards the back of the boat as speed increases the bow will drop and
    the boat will nose steer. This is a veering from one side to the other
    that gets worse as speed increases.         This can happen in wood
    boats also if the ribs supporting the bottom planks get weak and the
    bottom is driven up by the force of the water. 
      A hiooked bottom can usually be repaired. If this is the problem let
    us know
       Bill
374.6Ploughing = DangerousCIMNET::CREASERAuxiliary CoxswainTue May 16 1989 12:3421
    Re .4 & .5
    
    I think you've both touched on the most likely cause i.e. "bow
    steering". This is also called ploughing. Since you adjusted the
    the trim (to raise the stern?) this brought the boat onto plane
    more quick and without shipping water over stern. However, if the
    trim raised the stern (lowered the bow) to much, you will begin to
    plough or bow steer. 
    
    This is a very dangerous condition and worsen as you push for faster
    speed. The bow may "bite" to one side or the other and cause a radical
    turn or worse, catapult passengers by rolling the boat over.
    
    Fixed engine trim is a poor compromise on some engine.hull
    combinations. Check to insure that the bow is elevated enough
    to prevent ploughing and not so much to make it diffcult to
    achieve plane.
    
    Regards,
    Jerry
     
374.7Two notches?ROBOAT::HEBERTCaptain BlighTue May 16 1989 12:3934
Moving the engine out two notches seems excessive. When the boat is sitting
still, on an even keel; or, when it's on the trailer, relatively evenly, the 
engine shaft should be close to vertical. If two notches pushed it out 
noticably off vertical I think it's too much. 

But, if by "two notches" you meant that the pin is now in the second notch,
that's about where 99% of all engines belong.

If the engine is trimmed in too close to the transom the bow will plow at low
speeds, and you'll have trouble planing. If it's trimmed out too far, as you 
begin planing off the boat will "porpoise"; sort of alternately leaping out
of the water and pancaking back in. Both are dangerous.

The cavitation plate on the engine lower unit (some purists maintain that this 
is the ANTI-cavitation plate) should not be below the keel, but about even with
it.. The previous reply mentioned the possibility of a cut-out transom; either 
this, or a too-long engine shaft, would put the cavitation plate and the prop 
too far underwater. Then, when you speed up and begin planing higher and 
higher, you'd be trying  to fly the hull - which would fall off to one 
side or the other. 

Your boat is probably a semi-vee hull; a nice vee forward, to cut waves, coming
back to nearly flat at the stern, with rounded outside edges (or "chines").
A hull of this type should plane with about one to two feet of
the hull (forward of the transom) riding maybe an inch or so in the water; the
rest is skimming, sometimes out of the water.

As I recall, the older MFGs in this size range had an engine limit around 45 hp,
with some going up to 60 hp. Typical speeds were in the 30's, and 45 under top
conditions. 

<sigh> all this talk makes me want to go play boats!

Art
374.8A Hooked Bottom Sounds Right !!USRCV1::FRASCHTue May 16 1989 12:4319
    I think Bill might have the answer---a "Hooked" bottom! I doubt
    if this is caused by a lack of foam floatation material, but sure
    could be from a weak bottom/rib structure. One cause might be extended
    storage on a trailer that doesn't support the boat properly (especially
    if it sits there with any significant amount of water in it). Can
    you see any up and down movement of the bottom at speed? I'd expect
    it about 3 or 4' from the transom (right where the boat's planing
    surface is). Does the bow tend to ride low in the water at speed?
    
    The first thing I'd look for is movement of the bottom---an indication
    of some structural weakness (that can be fixed easily!!)
    
    Weakness in this area will also cause the hull to "Twist" at different
    torque loads which could cause the inconsistant response you are
    seeing.
    
    Even if this is the problem, its not a disaster!!
    
    Don
374.9Ploughing=Change UnderwearFREEBE::BMURRAYTue May 16 1989 14:0215
    
    I didn't get a chance last night to measure the transom/shaft (kids).
    The description of ploughing seems to be what's happening. I did
    not notice any visible movement in the bottom of the boat (although
    I was not really looking at the time). The rib/bottom looks very
    good. The trailer supports the boat with two long carpeted pieces
    in the rear and rollers up front. Drain plug is always out and trailer
    tilted if any water gets turu the boat cover. When I adjusted the
    trim I believe I did go back too far. It is in the third notch.
    Sounds like it should be in the second. The description of the boat
    in .7 is exact. Now I know what to look for next time I'm out. First
    thing I have to do is replace the pull cord recoil spring. Again
    I appreciate the responses (I was thinking about selling the boat
    after the maiden voyage but now I realize it might be my own
    inexperience ) I'll post what happens. Thanks,  Bob
374.10Say it isn't so :*(ARCHER::SUTERGentlemen, start your *marine* engines!Tue May 16 1989 17:3820
    Moved by moderator
    
                  <<< VICKI::SIE$DATA0:[NOTES$LIBRARY]BOATS.NOTE;1 >>>
                           -< Spring is in the air! >-
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Note 376.0                     Say it isn't so :*(                       1 reply
FREEBE::BMURRAY                                      11 lines  15-MAY-1989 15:16
--------------------------------------------------------------------------------

    I don't know if MFG made wood boats but this one is all fiberglass
    except for the top part covering the hull. How do I go about checking
    to see if it was refoamed correctly without tearing up the floor???
    I did notice that the floor has give to it at the very rear next
    to the transom unlike the rest of the floor. The floor was redone
    with plywood. I will check the motor/transom length tonight.
    Thanks (I think I'm starting to get a little depressed now but
    fortunatlyI got the boat very cheap and don't mine working on
    it)
    Bob
    
374.11A v-hull "feature"NRADM::WILSONIt doesn't get any better than thisTue May 16 1989 18:0031

I think that what you're seeing is a characteristic of small
deep-v hulls, there's probably nothing wrong with your boat.  As
the hull comes up on plane it lifts out of the water and tends
to tip to one side or the other, riding between the keel and 
one of the chines.  The boat will continue to lean in one dir-
ection until a weight or wind shift causes it to lean in the 
other direction.  Think of it as if the hull were sitting on 
your driveway, it would balance on the keel and tip to one side
or the other.  It has nothing to do with motor torque, although
it may seem that way because the boat will want to steer in the 
same direction that it is leaning.

There are a few things you can do to minimize the problem.  As
suggested in another reply, check steering torque fin adjustment
and for water in the bilge to make sure those aren't contributing
to the problem.  Try to mount things like batteries and fuel tanks
as close to the centerline as possible to minimize the weight shift.
And try to balance passenger and cargo weight evenly.  Smaller boats
are extremely sensitive to small changes in weight distribution.  A
full 6 gallon tank on one side with an empty one on the other, or 
too many passengers on side will throw off the balance.  

Your problem is a perfect example of that "tri-hull stability" vs:
"v-hull smoothness" tradeoff that was discussed in another topic.  
If you had the tri-hull you'd be asking us "what can I do to get
rid of this terrible pounding?".   8^)

Rick W.
                                       
374.12staright edgeSICVAX::SCHEIBELU can Teach A new dog UL TRIXTue May 16 1989 18:2114
    If you want to see if the bottom is hooked you have to check it two
    ways. one in the water one on the trailer. If the hook is bad enough
    you shoul be able to see it by putting a long straight edge on the
    bottom perpendicular to the transom parrel to the keel at several
    different points and look for a gap between the edge and the running
    surface of the bottom. If the hook is of a reaction type that is as
    water presure on the bottom would cause if the bottom is giving in it
    will only be visible with preasure on it. Put your mask and fins on and
    do the same test while the boat is floating. 
    
      Waiting to hear,
    
     Bill
    
374.13Now if it were a deep vee...ROBOAT::HEBERTCaptain BlighWed May 17 1989 12:2710
If this were a deep vee hull you could chalk it up as a characteristic trait.
Deep vees lean INTO a wind off either bow.

If your trim tab is not adjusted properly the boat will "pull" to one side
or the other at certain speeds. If the pull is pronounced at the speed you
frequently use, just loosen and move the tab IN THE DIRECTION OF THE PULL.

If boating EVER gets boring I'll sell out.

Art
374.14Ignorant but improving with help!FREEBE::BMURRAYFri May 19 1989 14:0516
    Hi again. I checked the shaft length (motor number starts with 15)
    and the transom is 15". Rules that possibility out. I will check
    for a hooked bottom this weekend. I know the "trim" is not set right-
    as I mentioned we were running in the third notch and it seems we
    should be in the second. The boat is definitly a deeep vee. One
    thing I don't understand in .13 is the use or adjustment of the
    trim tab. Is this "tab" the same small rod that adjusts the motor
    tilt? When we first had the rod in the closest hole near transom
    we were pulling in water. When we kicked it out to the third hole
    it was a noticable inprovement(no water-smoother ride but still
    not right) We'll try second hole. I can understand how this adjustment
    can affect planing... but I can't understand what you mean by adjusting
    in the direction of the pull?? Is this a seperate adjustment?? I
    think what I need is a "boating dictionary".
    Thanks much..Bob
    
374.152 different adjustmentsNRADM::WILSONIt doesn't get any better than thisFri May 19 1989 15:0824

The steering adjustment tab is a seperate adjustment from the engine
tilt.  It is located just above the propellor, and is adjusted by 
loosening the retaining bolt and turning it in either direction. It
is used to compensate for engine torque which tries to steer the motor
off to the side.

It is like a miniature rudder, so looking at it from the rear you 
should adjust it in the *opposite* direction of the pull.  And it 
doesn't take much, just a few degrees at a time and then test drive
the boat.

I wouldn't waste too much time checking the hull for a "hook".  Even
if it is hooked, what are you gonna do about it on a 27 year old
boat?  I still think the leaning problem is a characteristic of early
fiberglass boats, which to this day hasn't been totally eliminated.
In 1962 fiberglass boats had only been popular for a few years, and
hull design had a long way to go.  I saw the exact same problem with
my 1962 fiberglass Alumacraft, and most v-hulls under 17' that I've
ridden in tended to lean.  You should be able to fix any steering
pull, but the lean you'll probably have to live with.

Rick W.
374.16Procrastinating... AITG::KARRThu May 25 1989 13:2825
	This has been a great discussion. There is a lot of talk about a 
	hooked bottom. I know for a fact that my 1965 Duo, which is a 
	flat bottom hull, has a rather significant hook in it. The floor 
	was 'hacked' by the previous owner. The result is that I plow at 
	about 25 knots. (something I've gotten used too) It also causes the 
	engine to cavitate on a right turn. (the hook is on the port side 
	toward the stern of the boat.) at 23 knots, its plenty for the skiing
	and knee boarding I do so I hav'nt done anything about it. (I also
	allow a select few to pilot the boat because they are aware of the 
	handling characteristics caused by this)

	What I'd like to see is some expertise in tearing into the floor
	and repairing (what I assume) is damaged ribs. The rest of the boat
	(with much elbow grease over the past 3 years) is in real good shape
	and when my son gets a little older and is proficient with the rules
	of the waterway and more respectful of the boat in general, I'll 
	consider buying him a newer boat. This one is a super 'learner'
	for him for now; hense, I don't want to spend lots of money... 

	So... I guess if its not a real big deal and not gonna cost zillions,
	I would correct the hull problem. let me know what you think and 
	how you would go about it...
	BTW : Its a fiberglass hull and floor...
			Thanks gang!
								Roger
374.1795% OKFINSER::BMURRAYTue May 30 1989 20:0114
    
    I finally got the boat back in the water this past weekend. I adjusted
    the trim to the second hole and tightened the steering cables up
    a bit. What a difference! The boat runs alot better but stll feels
    like it wants to plow close to wide open throttle. It seems like
    the bow drops a little so it probably does have some sort of hook.
    According to the speedo the plow starts around 23 mph-(I'm still
    wondering if I'm not letting it plane enough) Maybe someday when
    the boat is empty I'll try w.o.t. and see what happens-splash!
    Right now I'm satisfied with the boat. I really appreciate all
    the help and advice I've gotten-I've learned alot and will hopefully
    be able to pass some of this along someday. Thanks again.
    Bob