Boat lists to port underway

[middle_road]

1985 Thompson Bowrider.
Merc 3.0L 140.

She lists hard to port once she's on plane on up to WOT.
Even with all passengers moved to starboard she's still leaning.
I acquired the boat last season and in the hold were two black 'fins' that, judging by the holes, appear to mount to the top of the lower unit. I've been searching and can't determine what these are called or what they do.

Thanks,
_mr

 

[middle_road]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

Bump?

Looking at trim tabs now.
Took it out friday with my lady and all weight on the starboard side
and the leaning still plagues me...

 

[QC]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

middle road,

The reason that you were not getting answers in the other thread is that it was someone else's thread . . . What happens is that you answer a question or one of us answers you and no one can tell if we are responding to the original poster or you. Gets very confusing. So I am started a new thread for you and we'll see if that helps.

Good luck!

 

[QC]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

So here are the first list of questions to nail this down.

1) Does she list at all when at rest?

2) Those black things are probably hydrofoils. Is there anything mounted to your anti-ventilation plate now? Don't think so, but need to confirm.

3) Have you adjusted the little vertical trim tab on the lower unit?

4) Hold off on the trim tabs although I like them a lot. We need to find out what is going on first.

5) Depending on how sever this is (sounds severe) could be normal. Caused by propeller torque.

 

[180shabah]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

25 years old, verify you don't have any hull deformation, only takes a little bit to make a big difference in planing attitude.

 

[middle_road]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

Thanks QC - wasn't sure if it was good or not to tag-along to save on subject clutter...

1- At rest she sit nice and level, side to side and bow to stern.
2- Nothing mounted in that area now. It appears that they on were
since one off the thru-holes is slightly messed up.
I've got some SS machine screws ready to install just waiting on some
SS fender washers to come in this week.
3- Yes. installed a new one last season and then tweaked it in.
She was pulling hard to starboard.
4- Holding off - waiting for input & suggestions.
5- Prop Torque... read about that in another thread.
Just replaced the prop this season. new 17P.

======

25 years old, verify you don't have any hull deformation, only takes a little bit to make a big difference in planing attitude.

Oh-My... what is hull deformation? is it pronounced or do I break out the straightedge and the laser?

Thanks!
_mr

 

[180shabah]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

do I break out the straightedge and the laser?

Straight edge will be fine. Check from the transom forward 4-5 feet. Check it every few inches from chine all the way to the other. Any hook (concave areas) or rocker (convex areas) will change the running attitude.

 

[LeisureLady]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

There could be a much simpler and easy to fix solution. I don't know what your experience level is, and I don't mean to insult you, I'm really new at boating and was making this mistake so I thought I'd throw it out there... you could be over-trimmed. If your boat is perfectly level at rest, not listing or dragging at plowing speeds or on the acceleration to plane, but only veers off and tries to take control when you get onto plane perhaps you need to adjust your engine trim up a little when you come over the top onto plane.

Here is a description of 'bow steering' that I found online last night to show someone else a description of what the problem I had was since they'd never heard of bow steering:

The trim angle of the outboard/stern drive has a distinct effect on the planing angle of the boat which, in turn, significantly alters top speed and handling. The engine/drive should be trimmed in for best start-up acceleration and shortest time to plane. The engine/drive would then be trimmed out for peak performance. If trimmed "in" (under) too far (Figure 7-19), the bow drops and the boat runs too wet. In this condition, top speed drops, fuel economy decreases, the boat may over-steer in one direction or the other ("bow steering"), and steering torque will increase (to the right with a right-hand rotation propeller). Occasionally, extreme trim under can cause a boat to list to the left (with a right-hand propeller).

 

[QC]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

2- Nothing mounted in that area now. It appears that they on were since one off the thru-holes is slightly messed up. I've got some SS machine screws ready to install just waiting on some
SS fender washers to come in this week.

Leave that stuff alone. Can make it worse and most here are violently opposed to hydrofoils. There are a few applications that appear to be helped, especially very small OBs on small planing hulls.

Yes trim can make a difference, and some props are worse than others. If it is very pronounced it could be in the hull as Shabah notes. Good luck!

 

[middle_road]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

There could be a much simpler and easy to fix solution. I don't know what your experience level is, and I don't mean to insult you, I'm really new at boating and was making this mistake so I thought I'd throw it out there... you could be over-trimmed. If your boat is perfectly level at rest, not listing or dragging at plowing speeds or on the acceleration to plane, but only veers off and tries to take control when you get onto plane perhaps you need to adjust your engine trim up a little when you come over the top onto plane.

Thx,
I bring the trim back up for about a 3 count I'd say after she is all the way down
and she's up on plane. Rev's sound better and she definitely handles better.
But she is still listing.

_mr

 

[middle_road]

Re: Boat list to port on full throttle

Re: Boat list to port on full throttle

Leave that stuff alone. Can make it worse and most here are violently opposed to hydrofoils. There are a few applications that appear to be helped, especially very small OBs on small planing hulls.

Yes trim can make a difference, and some props are worse than others. If it is very pronounced it could be in the hull as Shabah notes. Good luck!

Yeah, the deformation around the holes on the outdrive and on the foils gave
me pause as to re-installing them. I was wondering if they were causing too much stress.
I'm going to bring it over to the house this weekend grab the straightedge and a crayon and check out the hull...

_mr

 

[Summer Fun]

Re: Boat lists to port underway

She lists hard to port once she's on plane on up to WOT.

Move the fat ladies to the other side.

Sorry you left'd the door wide opened on that one !!.

 

[middle_road]

Re: Boat lists to port underway

Move the fat ladies to the other side.

Sorry you left'd the door wide opened on that one !!.

tried that at the beginning... also moved cooler to the starboard side...