[Alberg30] A30 Yanmar 3GM

[Peter Amos]

Scott,I have a Westerbeke M3 20B with 2:1 reduction.At 2500 engine rpm I get 5knots with a 12x9  3blade machine pitch prop.This prop allows the engine to go to max 3500rpm if I push it.At 2500 rpm the engine is at max torque but only putting out 15hp.I think what you need to know is the h.p. the A4 develops over its rpm range with a transmission reduction.Have a look at www.westerbeke.com >diesel engines>technical for the M3 20B.There is a useful little graph showing the relationships between rpm,torque,hp and fuel consumption.This is the sort of information you need before getting into expense."The Propellor Handbook" by Dave Gerr gives a lot of useful information and although some of it is very technical the formulae are interesting
Peter Amos
Tait Tait #478
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