25hp kicker motor prop.

[elkhunter338]

Was wondering if anyone has some information on what size prop I should go with on a 1995, 25hp, 2 stroke johnson, 2.15:1 gear ratio, 4500-5500 wot rpms. At this time I have no tach.
I have the motor on a 21 foot cuddy cabin boat, approx 3200lbs. as a kicker motor.
Current prop is a comp. prop 4 blade, 10.5x11. Top speed is 7 mph (gps) @ sea level. I know I am not in the 5,000 rpm range.
I have a 15hp 2 stroke johnson with a tach and know what 5,000 rpms sounds like.
I am looking to get the rpms within 4500-5000 and get top speed out of it since this is my spare motor if my main quites. Would like more than 7 mph and not lug the engine.

Options:
Piranha prop 3 blades (9.5x5, 9.5x7, 10x9)
Solas alum. prop 3 blades (11x9, 10.5x9, 10.5x10, 11x9, 10.5x11)
OEM 11.25x7, 11x9

 

[trendsetter240]

Re: 25hp kicker motor prop.

Hey there, it's going to be really hard to get into the correct RPM range without a tach on the 25. Can you use your tach from the 15hp motor temporarily with the 25?

Changing pitch between 11, 10 and 9 inch pitch props can have a dramatic effect on RPM. You really need to have a tach to avoid over reving your engine.

From the prop options you posted my preference would be for the solas props. However as a kicker motor I would think a 4-blade prop would be more suitable than 3 blade.