Boat Pulls Left When Trimmed Up

[RetrActv]

I've had a 17' Smokercraft with 125 HP Mercury for about a year now, and I just started noticing last week that the boat pulls slightly to the left when trimmed up while cruising. When going straight with trim down, I can keep it very straight by keeping the steering wheel straight. At WOT, I have to turn the wheel somewhere between 60 and 90 degrees to the right to keep it straight.

Could this be something that was recently caused by a bent skeg, or a bend in the prop? The prop looks ok, but perhaps there is something I'm missing? I've tried adjusting the steel-colored trim tab on the anti-cav plate to compensate, but it doesn't seem to have any effect at high speeds.

Could the motor not be straight on the boat? Using my eyes and a few quick measurements, it certainly isn't way off in either direction.

Is this something that is just inherant with the boat, and I shouldn't worry about it? It doesn't seem to be unsafe, by any means.

Thanks!

 

[Chris1956]

Re: Boat Pulls Left When Trimmed Up

Boats tend to pull right when trimmed down, and left when trimmed up. You should be able to adjust the zinc above the prop, to make the steering more neutral, at the trim level you normally operate at, but it will have different effect at different trim levels.

 

[jaymasta]

Re: Boat Pulls Left When Trimmed Up

Boats tend to pull right when trimmed down, and left when trimmed up. You should be able to adjust the zinc above the prop, to make the steering more neutral, at the trim level you normally operate at, but it will have different effect at different trim levels.

I have a 14ft f/g with a 65 merc and I find that it also varies somewhat with weight in the boat, eg. with just me in the boat at a certain trim level I will be going perfectly straight, if someone else joins me in the boat and I fill both my gas tanks at the same trim it might slightly pull in either direction, I don't have auto tilt/trim so I can usually correct the problem by either lowering or raising a pin level on the trim, Iam sure you have auto tilt/trim with a 125, so I would try playing with the trim a bit and seeing what affect that has on it, also don't forget about the tourqe of the prop that will play somewhat of a role in the boat pulling which is normal, try to correct that with the anode

 

[RetrActv]

Re: Boat Pulls Left When Trimmed Up

When somebody says a boat "pulls" to one side, does this mean the tendency is for the boat to veer in this direction even though the steering wheel is straight, or that there is a force to that direction but the alignment isn't affected?

Maybe I made that sound more complicated that I need to. My boat veers slightly to the left at WOT, trim out. Is this to be expected by the torque effect of the outboard?

Oh, and would a bent skeg or cupped prop cause anything like this? I've looked at the skeg and the prop, and they appear ok. The prop has one dig in it that doesn't appear serious, but could this cause it (if it isn't normal)?

 

[Chris1956]

Re: Boat Pulls Left When Trimmed Up

Jay, When you add a person, fuel or some other weight to the boat, it changes the trim. This will change the amount of "pull" in the wheel.

Retr, When I trim up the motor on my speedboat, the steering wheel pulls left. If I were to let the wheel go, the boat would go into a left turn. A bent skeg could contribute to this action, but the main cause is the right-hand props we use, hence the need for counterrotating props on dual motor boats.d

 

[Texasmark]

Re: Boat Pulls Left When Trimmed Up

Talking about torque, if I am running at WOT and slam the throttle to N (move it very fast) the boat yaws to the right or left (forget which way) about 5-10 degrees when the torque of the prop is released.

You don't realize the torque is there going up to WOT or coming down slowly, but it's still there.

And I totally agree with Chris and Jay's comments about steering torque variances. But my current boat has Morse/Teleflex rack and pinion steering which is no feedback and you can't tell (barely) the torque changes with different trim positions........but it does.....don't have to wrestle the wheel like the old boat.

Mark

Mark