2 blades vs 3

[Dave Humphreys]

I recently purchased a new Beneteau 331 and opted for the additional expense of the Yanmar 3GM, 27 hp over the standard Westerbeke 27. I had had very good and reliable experience with my J-30 and its Yanmar 2 cylinder albeit shaky engine. I am pleased with the smooth quiet performance of the Yanmar with its 3 blade prop but wonder why the Westerbeke uses a 2 blade in the same boat. Are the engine dynamics so different between these two same-horsepower 3 cylinder engines? Or is the 3 blade a better (more costly) choice that is not included in the standard Westerbek engine for the boat? Any experts out there please comment.Regards,Dave Humphreys

 

[Ralph M.Johnstone]

Less Cost ......................

....... is the only reason for using a two bladed rather than a three bladed prop. When I had mine fabricated, I was told that a two bladed is about 1/4 the cost of a three bladed. This shop does NOT fabricate two bladed props.Regards,s/v Isalnd Hunter

 

[James Sladky]

2vs3 blade

Some 320's went to 3 blade as we felt we were under powered with the 2 blade. Agree with first post on price. If you are a racer the 3 blade will decrease speed as it increases drag.

 

[Kevin]

Possible three blade cost diff

Hello Dave,Being a propeller manufacture and distributor I would have to say that the additional cost of the three blade is the reason you ended up with the two blade. In almost all cases a three blade will out perform a two blade in the motoring and vibration areas. If sized right the two and three blade will load the engine at the same amount. Hope this helps and please let me know if you have any other questions.Kevin