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post #1 of Old 02-02-2013 Thread Starter
jrd22
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Location: San Juan Islands., WA, USA
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Repower confusion (horsepower)

Went to the Seattle boat show yesterday to look at a couple of different engine options for a repower and just to see what was new (haven't been for several years). I answered some questions I had(Beta is at the top of my list now), but came away with some new ones regarding how much horsepower I need (or maybe how much I can use is a better way of putting it). The rep for Beta had a nifty program on his computer for determining hp requirements and for our boat he recommended the 38 hp model. The original Volvo we have now is 62 hp. His recommendation is based on the following specs for our boat, prop, etc.
LOA 40'
LWL 35'
Disp 23,000 lbs (26,000 loaded for cruising)
Beam 12'8"
Prop 18" X 12 fixed three blade sail (will probably install 3 blade Max prop)

His program showed that with only an 18' prop there is no way we can use all of the horsepower we have and a 38 hp engine would drive the boat at hull speed at WOT. I would at least go to the 43 hp model because it is a lower rpm engine and jumps up to the heavier duty trans., but even that is a huge drop in hp from what we have now. I like to run things easy, we motor at around 26-700 rpm now (3500 rpm WOT) which gives us a little over 6 knots. The sail prop doesn't give us a lot of thrust, I think we would gain quite a bit of speed with the max prop. The smaller engine would be easier to install, and cheaper, but even 43 hp seems low to me.

So I'm curious, those of you with similar size and displacement boats, what horsepower and prop size do you have, and what speed/rpm do you get out of it? Thanks!

John
SV Laurie Anne

1988 Brewer 40 Pilothouse

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