Johnson 40 HP Trim

[Release2Grease]

What makes a boat pull right and roll left even after the trim tab has been adjusted ?

[STUMP HUNTER]

Check and make sure your boat is not over weighted on one side.

[Eager Beaver]

Add a foil to the fin on the motor, It will help stabilize it a lot.

[Matt Smith]

The motor may be mounted too high or too low on the transom.

[Barnacle Bill]

FYI we now have a forum just for problem like this. Mechanics Corner - boats, motors and trailers - Crappie.com
With your motor in the normal running position look at the anti-cavitation plate. It should be within 1" of being even with the bottom of the boat. As mentioned make sure the boat is loaded evenly. Next and not to insult your intelligence, are you adjusting the trim tab correctly? Pulling to port or starboard is usually cause by the torque of the prop. To compensate for this the trim tab must be adjusted (a little at a time) in the same direction as the pull. Also make sure the motor is mounted exactly in the center of the transom.

[Scrapper]

Everyone is right...all these things can have to do with your problem. Are you in an aluminum boat?? Have you hit anything?? If your trim tab is adjusted correctly...have you continued to adjust trim tab to try to compensate for the pull?? Are you at the extent of adjustment??

Get on a level preferably concret slab and put a staright edge or plum bob to it. Make for sure your engine is mounted straight, square and true. I would be checking under the hull if all of that is okay. A small dent in the bottom of the boat will cause effects like that.

Vertical rise and fall will not effect roll or pulling very much if everything else is right...that will effect your planing speed...porpoising...top speed...wet surface of hull on water and such.

I would try to compensate as much as possible with the trim tab.

There has to be something out of line there. If everything is staright and at the correct angles...it has to be a hull issue....could be a bent prop...you would get some vibrations though.

The hydrofoils and such compensate for a poorly setup boat. If a boat is setup properly...has suffiecent power for the boat...and is propped right...a foil is not needed. They will help boats plane faster and use a higher trim setting when there is no power tilt and trim.

Check that sfuff out and repost. We'll get it figured out.

[Matt Smith]

Vertical rise and fall will not effect roll or pulling very much if everything else is right...

Oh yes it will. That motor has a relatively large diameter prop. If it's too low it will roll that boat right on its side no matter if "every thing else is right".

[Scrapper]

Actually the lower you set the engine on the transom the more stable it will be. Thats the point of using the jackplate to get the engine further out of the water. This puts less of the engine in the water...less drag...which also decreases stability because you have less "fin" in the water to help reduce the rotational forces of the prop...pull it up too much and you will chinewalk....let it back down some and the forces from the prop rotation will be less.
Also depends on the width, weight, and hull design of the boat.

[wannabe fisherman]

The hydrofoils and such compensate for a poorly setup boat. If a boat is setup properly...has suffiecent power for the boat...and is propped right...a foil is not needed. They will help boats plane faster and use a higher trim setting when there is no power tilt and trim..

I put a foil on my 15.5ft Bayliner w/50 hp Force right after I got it 2 yrs.ago. it pulled right real bad so I called the Bayliner people and told them how it was set up and they said given the hull design it wasn't necessary and could cause it to flip. just my experience with them. Boat handles fine without it.

[magnum500]

I have a Javelin 379T with a Johnson 150 Faststrike. I put a hydrofoil on it for two reasons. The first reason was for better hole shot. It does get on plane quicker. The main reason for it is that since the boat does not have hydraulic steering it is a little tougher to handle. I bought the trim tabs that mount to the hydrofoil and adjusted them until the steering torque was eliminated. You can now run down the lake and drive it with just two fingers. If you let go of the wheel it goes straight. No pull at all. well worth the money.