Back-up prop

[Muskie Bill]

I have a 2000 Javelin f/s 19.5 boat with a 175hp carburated outboard. The prop on my boat is a Renegade Bass 13.5x 23pitch ss 4blade. I have the opportunity to purchase the same type of blade but with a 25 pitch. This would be a back-up blade. My boat can do approx 68mph @4800rpm lightly loaded. what differences in perfomance could I expect if I were to swith to the 25 pitch blade?

 

[Dhadley]

Re: Back-up prop

I sure wouldn't go with any more pitch. At 4800 you're lugging the motor pretty bad now. But the tach may be off since the numbers are so far off - at 4800 the theoritical speed is only around 60. Even with a 2:1 gear ratio the numbers are off.

If it were mine I'd get the tach reading verified before buying another propeller.

 

[Muskie Bill]

Re: Back-up prop

Thanks for the advice,I may have to wait till I am back on the water to check the rpm's. I am curious how you calculate the numbers to get top speed, do you use a table or did you need to calculate it? I believe this engine has a gear ratio of 1.85 :1.