I have a 17ft riveted bass boat with a 50hp outboard and a brand new SS prop. No Tach, No Spedo.
I took my GPS with me and found my top speed is now 38 mph which is up from 34 with the aluminum prop.
I also found that I can get 39 with just an one more click of up trim but at that point the boat begins to lean left and gets hard to steer to the right.
So, I go home thinking I will adjust the torque tab on the outboard to the left (counter clock wise) to make the motor want to steer to the right and here is what I found.
My tab was set on 1.5 which looked to be just a little left of center and would only go left to 0 which was just a little farther left of center. It seems that all the adjustment (1-12) is to the right.
The extra 1MPH is not important but I would like to understand the forces at work here and what I am missing.
Easiest way for me to remember which way to move it is this: Standing behind the boat, you know which way the motor swings to turn the boat. Rotate the trim tab in such a direction that water pressure against it pushes the motor to swing in the direction that you want in order to assist your manual effort. Remember, it pushes against the AFT end of the motor. This is easier for me than trying to remember all the right vs left stuff which I forget an hour later.