Prop Pitch Determination??

Ship For Brains

Recruit
Joined
May 25, 2006
Messages
1
I just bought a 1984 Bayliner Contessa 2850 Command Bridge with a Volvo Penta 270. The previous owner said it had "too much prop" on it and should be changed. I am trying to find the ideal prop for the boat to get it to plane out reasonably quickly and still have a reasonable top speed. But I do not know the reduction ratio, current prop size or anything. Is there a standard reduction ratio for the Volvo Penta 270? Any help or suggestions out there would be apprectiated.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Prop Pitch Determination??

You'll need to take it out and run it first.<br /><br />We'll assume that your engine is in good running order and tuned up.<br /><br />1. Observe and take note the wide open throttle(WOT) RPM. <br /><br />2. Determine the pitch of your current prop is. (It should be stamped on it)<br /><br />Then come back here with the actual model and engine/drive info and prop pitch and someone here should be able to tell you what the correct WOT rpm SHOULD be and a suggested prop pitch.<br /><br /><br />Regards, <br /><br />Rick
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: Prop Pitch Determination??

I agree if engine is running right then determine you WOT RPMs. Check your engine recomemded WOT RPMs. Going 2 inches lower in pitch with the same style prop should increase RPMS by 400. If your turning 4200 RPMs and reduce pitch by 2 inches should end up around 4600 RPMS. This will give you better hole shot, faster to plane and likely loose 3 MPH top end.<br /><br />You must know What Your WOT RPMS are and prop size, nunber of blades and pitch before you start.
 

tim10034

Seaman
Joined
Jan 17, 2004
Messages
60
Re: Prop Pitch Determination??

i have a 1996 24 four winns with a 7.4 volvo ... i think im getting to many rpms at wot....its the prop that should have came factory installed it has volvo stamped on it...getting about 4800 rpms...is this right???
 

Purduebarry

Petty Officer 1st Class
Joined
Sep 29, 2005
Messages
378
Re: Prop Pitch Determination??

Ask the mods to move this or repost the thread in "Props..., you'll get a much better answer!
 
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