I have a 1977 Johnson 75hp Stinger and it has a 14x17 prop on it, what size should it have/

Question

What does the 14x17 stand for, and is this the size i need for a 75 hp johnson on a 20' pontoon for a good performance? It seems a little sluggish to me. I would appreciate any help. Thanks

Answer 1

14" diameter, 17" pitch.

You want to select a prop that will let the engine make 5000-5500 RPM at full throttle with a normal load. A higher pitched prop will lug the engine, less pitch will overrev it.

If it's running at the top of that range now, then that's the best you can do with that motor on that boat.  A pontoon will be sluggish.

Assuming the motor is making all the power it can.

Decreasing the pitch by 1 inch will increase RPMs by about 200 (props of similar design). A good prop guy can customize a prop to optimize a boat/motor combination but you probably don't want to get too fancy.

If it's turning 5200 with the 17-pitch prop, try a 14 x 15.