prop diameters
 

I am currently running 16.5 X 29 4 blade cleavers on my 87 Top gun. These appear to be too big. However I am a little confused about prop diameter. A friend with the same boat but much less HP is running 27 pitch but 17.5 diameter.So,do I go smaller pitch but bigger diameter? Any ideas ? Bob

It depends on the boats running attitude.
More diameter more stern lift. You mentioned too big. I guess that means the R's are too low. Try a lower pitch and see what happens. Try your friends props.
Your vintage TG used to run the 17-17.5" props.


Brett

Thanks,Brett
I planned to call you after I got a little more info. The Gun came with 16 x 28 three blade(SSM3 with the 3A shaft). Cruise sucks.I'm going to put those on and test as well as the 16.5 29 4 blade. Then I'll call. Thanks again,Bob

FYI,haven't tested yet but I do have some info
16X28 three blade......45 mph at 3500 rpm
16.5X29 four blade....50 mph at 3000 rpm
the prop calculators don't allow for three/four blade or dia.

Slip % is a tool (sometimes over used). There isn't a way to put the number of blades into into the mathematical equation.
The final slip % number can tell you if going to more diameter or blades is a good option.

Brett