what prop?????

[lyncraft_mechanic]

I have a 14' fiberglass boat that i just installed a 2002 40hp johnson outboard on and my top speed is only about 25mph! do you think i could get a little more speed if i switched to a different prop? right now I am running a 3 blade 11 3/4 x 17 prop. any suggestions???????????

 

[Silvertip]

Re: what prop?????

11-3/4 x 17P should provide better performance than that. That prop (and 15P) are fairly common on that engine and boats in the 14 - 16 foot range. Are you sure the engine is running right? With that much power on a 14 foot boat, either the speedometer is wrong, the engine is not running at wide open throttle, the boat is full of water soaked foam, or the engine is not mounted high enough. Something is not right. If the engine is actually running at 5500 RPM (which is where it should be at WOT) your numbers equate to 31% slip. That's terrible so something is wrong with the numbers. Without any rpm readings there isn't much we can help you with.

 

[lyncraft_mechanic]

Re: what prop?????

i currently do not have a tachometer but i noticed some extra wires on my wire harness and i do not know what they go to, could they go to a tach? is there a way to tell by the wire colors?