Re: 25 johnson to 35 hp prop question ?
As with any prop change it is based on the performance with the present prop.We need the boat,typical load,prop size,max rpm and speed.
A tinytach is reasonable,easy to install and will fit any other 2 cylinder 2 stroke motor.A gps is best for speed.The 9 X 10 is a good starting point.
Also wouldn't hurt to finetune your setup before selecting a prop.vertical height, raise the motor a little at a time by placing 1/4' sticks on the transom.Raise it to a point just before venting(loss of prop grip) becomes a problem.Be sure it pumps water and has a good grip.The antivent plate even with the bottom is considered a starting point.This alone could gain a couple of mph under ideal conditions.After fine tuned the prop selection could gain even more height and performance.The height will be limited by the older gearcase design but worth a try.
