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Kendall249
23-01-2006, 07:06 PM
thinking of playing aroung with some different prop set-ups. The boat has a 14.5 x 19 pulling 31-32 kts @ 5500 (150hp v6 on 7m longboat), first might try 14.25 x 21. Any advive would be appreciated

HarryO
23-01-2006, 07:38 PM
G'day Kendall..

Depends on what you are trying to achieve.

Are the figures you've quoted with just you onboard,
or normal load, or more?

Does your load vary much trip to trip?

At 5500rpm, you've still got a few hundred revs to
play with..

Going bigger in diameter and pitch will drop the revs
even lower...

What are you trying to achieve?

Harry..

Kendall249
23-01-2006, 08:02 PM
I wish to try dropping the diametre of the prop by 1/4 inch, though raising the pitch from 19 to 21 inche. The decrease in the diametre should raise revs, but the increace in pitch will drop max rpm. I'm interested in how much of a decreace in max rpm and if there would be an increace in cavitation. The boat capable of carring a total of 1400kg consisting of people and gear. In my case I fish with 2 to 3 people. The boats has a tendancy to ride better 28 - 30 kts in the right sea. So overall I would like to increase the speed of the boat in the 3500-4500 rpm range ( if possible).

HarryO
23-01-2006, 08:32 PM
Ok....

Sounds like you've got some experimenting to do..

If all else fails, ring Steve @ SOLAS propellors.....

Keep notes on all the data you gather, will be a big help.