3 GMD

[Brud Helhoski]

I have a 33 ft Hunter with a yanmar 3GMD it is not the original engine. I have a two blade prop on it now, will a three blade give me better motoring performance? what size three blade should I put on? I know I'll lose some sailing speed, but how much? I'm not racing anytime soon. The price and maintenance on a feathering three blade don't seem worth it to me right now.

 

[Sam Lust]

Have 3GM also

I swapped the 2GM for the current 3GM30 a couple of years ago. What a difference. I installed a 3 blade at the same time. A Michigan Wheel "Mickey Mouse Ear" style which ended up as (if I remember correctly) 14 by 14. I can't say I noticed any difference in sailing speed. How much speed would you lose dragging your hand in the water? That's about the size of the blade so you get to figure it out. The good news is motoring performance. With the orriginal pitch I could hit 7.1 knots by GPS. After repitching 1 inch higher It's about 6.9. Cruising at 2750 RPM's is right around 6 knots. Very nice when you want to get somewhere. It accelerates well and pulls like a truck.The less good news is that you will experience rudder pull to starboard at higher speeds and under acceleration, and possibly slightly increased reverse prop walk, but neither is all that big a deal.I'd say give it a try. The worst you have to lose is about $250.00