Yanmar 2GM is a wimp

[Jeff]

We have owned our 88 Hunter 33.5 for about 9 months and love how it sails. We don't like the lack of power however behind the wholly inadequate 18HP Diesel that came standard in the 88 boats.Any ideas as to how we can increase the the boat speed and prop thrust when under power?

 

[Charles Weikel]

No power? No way!

Boats are unlike cars -- you cannot create (significant) more thrust by more power. The screw is matched to the engine hp. So you need to increase hp and match it to a new screw.However, your boat should be OK at 18 hp to move faster than hull speed (about 6 knots).Is the engine operating at the proper RPM? (about 3,000)Is there a line/junk wrapped around the shaft or rudder? Screw bent or damaged?Check some of the postings on the diesel forum on this subject....

 

[Andy Falls]

Wimp out

I concur with the pervious response. It 's not a speed boat, but its no wimp. Your diesel could be underperforming due to bad/blocked fuel or air, or clogged injectors.Take note that it may reach 3000 rpm in neutral or with very little load, but choke down quickly. Thats the sign of a sick diesel.(and of course we all assume that our bottom is slick as teflon!)

 

[Stephen Ostrander]

slightly underpowered

My boat will cruise at 6 knots at about 2800 rpm. Motoring into headwind and seas will knock the speed back to about 4.5 knots. The late model 33.5s were powered with 3GM30s. Who says Hunter doesn't listen?

 

[Colin Campbell]

Yes underpowered!

For sailing anywhere with a short fetch 18hp is fine, however, I have faced 10' seas in Lake Erie that knocked me back to below 2 knots in my 2gm equiped 33.5. If I were to face this sort of wave action frequently I would be looking for more power. Anyone have thoughts on a lower pitched 3 blade and up some speed for more power. Less pitch = less torque = higher rpm?

 

[Jerry Woznicki]

I felt the same way.

I have a 31' (9800lbs.)with the same engine and I had the same feeling at 6 nph, although after switching to sail and selling a gas eating fast monster which daily took 50+ gallons @ $1.80 , I have really gotten use to $1 per gallon about three 18 gal. tank fulls this season. Maby a little slow but that what sailing usually is.