2-blade to 3 blade

[Steve O.]

I have a 1988 Hunter 33.5 with Yanmar 2GM20F 18 hp. The boat displaces 11,000 lbs. (HOW lists the original 2-blade prop as 15x14 but this might be for the 27 hp 3GM30F engine) I would like to re-prop to a 3-blade, can you tell me what size would work?

 

[Kevin]

16" x 10" 1" shaft 3 blade

Hello Steve,I show a 16” x 10” three blade 1” shaft and a 16” x 11” two blade 1” shaft. That was with the 2GM. Hope this helps. Kevin

 

[james rohr]

prop selection

on the marine diesel direct, torrenson site there is a guide to match your particular yanmar and trans. with the correct prop size and pitch. the link will take you directly to the page.

 

[Steve O.]

thanks guys

I guess I need to double check my reduction ratio.

 

[fred miller]

Propper Prop

I just relaced my 2 blade on my 35.5 with a 3 blade Michigan Sailer 16X10. My engine is a 3 GM 30 F and while the boat is a little larger than yours the new prop is just about on the money with a cruising speed of 3200 RPM [ideal would be 3400]. Next year I might pitch down to 16X9 to bump up the crusing RPMs a smidge. My point is a 16X10 is probably righ for you, but go to Michigan wheels web site and they can give your the correct prop specs instead of my guess. You will need to tell them the trans reducing gear info [mine was 2:61 to 1], engine info, boat displacement, cruising and maximum RPMs.Good luck,Fred Miller S/V M SquaredPS The 3 blade prop made a mega diffrence in maneuverability and speed under power without much drag loss under sail if you go to the SAILER MODEL.