WE had an MD2B
with a two bladed prop in our Westsail 32, 10 tons displacement
. It was fine for us but I'm not a big engine
user. Never had a problem powering at 5 knots in calm conditions and about a 1.2 gallon an hour consumption
. The one or two times we had to buck into a chop and strong headwind, motor sailed largely because the motion was easier.
Delivered 2 Westsails from SF to SoCal, one with an MD3B
and the other with a 4-107. No question, you could do more with the extra power and big three bladed prop like stop the boat under full sail in Santa Ana winds by throwing the bigger engine
into reverse and red lining it. Not something I did but a clueless owner who tried to sail up Newport Beach
Bay into a narrow deadend channel.
Today people seem to think that a bigger engine is a replacement for good seamanship and are going for bigger and bigger engines. Seem to recall
someone re-enginging a boat similar to yours questioning whether he should go from the current
50hp engine to a 70hp. Personally think for optimum power and resaie value an engine around 25hp would be the best size. That is what we've go on our current
7 ton boat and it has been just right. If you want the best fuel
economy and are content to use the engine for getting in and out of the slip and no wind
condition powering then a 15hp engine would suffice.