Adjusting trim tab anode on outboards?

So I’m getting ready to do some maintenance on my motor (2006 Yamaha 150 TXR) and noticed that the trim tab above the prop is completely loose. I tried tightening the bolt, but seems like it’s corroded out so that it won’t tighten all the way anymore.

I plan on replacing the trim tab anode when I do my water pump, but whats the best way to set it back to the correct position? I know the general idea is to counteract the sideways thrust of the prop - do I just take the boat out and see if pulls to one side and adjust the angle of the tab based on that? or is there a more accurate way that doesn’t rely on “feel” to make sure the boat is actually tracking straight in the water?

just out of curiosity, what is the relative importance of setting this thing correctly? Does it really make a noticeable difference?


Yes, it makes a huge difference with conventional cable steering. With hydraulic or the newer NFB steering you won’t be able to feel it as much, but it will still make a difference.

Single engine outboards with standard rotation will always pull to the right, due to prop torque. The tab has to be moved to the right of center to balance this. Always move the tab in the direction that the boat is pulling. A good starting place is about 10 degrees to the right of center. That will get you close to the ballpark. Make a little index mark on it and run the boat. If it now pulls left, move the tab just a little left. If it still pulls right, move it a little more right.

Capt. Larry Teuton
Cracker Built Custom Boats

larry is dead on