Bent Prop, Boat Pulling Left?

[Reminscent]

I backed my boat into my garbage can last week (which pushed it back to the garage door). Anyway, no real damage that I could see, but the last time out the steering was off at WOT with the trim most or all the way out. It would veer to the left slightly, almost like it needed an alignment. With the trim all the way in and the boat at WOT, this was not present. I'm guessing it's related to RPMs. I'd have to turn the wheel about 1/5 to the right to keep it straight.

I've inspected the motor position and looked for anything bent/misaligned, and all looks good. I didn't put a lot of pressure on the motor when I backed up, as there was no damage to my aluminum garage door. Based on the motor's position on the transom saver, it appears that I would have hit the prop first.

Could there be a bend or cup in the prop that would lead to this condition, as the RPMs climb over 4500 or so? The motor is a 115 Merc two stroke. I've tried adjusting the aluminum trim tab on the cavitation plate, and this has no effect on the pulling. I'm guessing an out of balance prop might have this affect at these high RPMs.

Any ideas?

 

[tiller7104]

Re: Bent Prop, Boat Pulling Left?

Look above the prop is you little skeg thingy is it off? If it is that is your problem!

 

[tiller7104]

Re: Bent Prop, Boat Pulling Left?

Trim tab LOL I could not think of the name of it.....some have a allen screw in the middle, some have a bolt head.....stand back and eye ball it, It should be reletively straight......look at it good and make sure it moved..ie: cracked paint...scratch etc...I would start there!

 

[diaric]

Re: Bent Prop, Boat Pulling Left?

yes, sounds like the trim tab/anode got nicked, moved or knocked off

 

[jimmbo]

Re: Bent Prop, Boat Pulling Left?

Most boats pull to the right with the motor trimmied in all the way. As the motor is trimmed out the steering should neutralize and then as it is trimmed further out the boat will then pull to the left.. It happens because when then the prop is anything but parallel to the direction of travel one side of the prop(port or starboard) will have greater or less pitch than the opposite side. This cause the engine to twist on the steering axis.

 

[tiller7104]

Re: Bent Prop, Boat Pulling Left?

JImbo, you missed what I was saying.....not the trim per say., but rather the "trim tab" the vertical fin that is adjustable from left to right...Some outboards it is an anode. I know I bumped the one on my Merc 150 back in the day and when I nailed it my boat hung an abrupt right LOL......That is my thinking if he backed into a door, and this is something different than prior to the accident. Just a thought ?