Hunter 30T Prop

[Terry Hunt]

I purchased my Hunter 30T (1991 hr model) 3 months ago and have found that under power (Yanmar 2GM20(F)she cruises at only 4.5 kts at 2400 rpm, which is the max continuous rated cruise setting for that engine. I'm wondering if this is normal for this boat, or should I be looking at a more efficient prop. This seems slow to me compared to other boats and I would like to get up to 6 kts if possible. As far as I know, the two-blade prop on the boat now is the factory original. Doeds anyone out there have any recommendations re prop size and pitch?

 

[Steve Dion]

Terry, that is not the max.

Terry:The max. rating is more like 2900 rpm. The max rating is 70-80% of 3600 rpm's. You want to make sure that you have the correct prop for this engine. Your engine should rev. to about 3400-3600 under wide open throttle in gear. If you rev higher than this in gear you may be under propped. If you cannot get these RPM's you may be over propped. You also want to be sure that your bottom is clean.The 2GM engine really should be enough for your boat.

 

[John Tesoriero]

new prop

I had a similar problem with my older 1980 Hunter 30. It has a 15 HP Yanmar 2QM15. I changed the prop from the factory original 13 X 13 2-blade to a 13 X 9 3-blade. The engine RPM now comes up to speed and the boat speed increased as well. Any of the prop manufacturers or suppliers can offer good advice on your problem. Be certain to check that your engine is operating properly.

 

[Steve Winkle]

Four Checks

Terry,Check the following four things first:1) Is the prop nut tight?2) Is the bottom clean?3) Is the engine running efficiently?4) Review the archives on this site for what others have had to say.On my '91 30T with a clean botton at 3000 rpm I was able to move at 5.9 kts.Fair winds,Steve

 

[Roy Mosteller]

Performance On My 30T

The previous owner of my 30T (1991) replaced the original 15x12 (2-blade) with a 15x10 (3-blade). It seems to do well and I cruise about 6.2 kts at 2750 rpm. At 2000 rmp I get 5.0 kts. This may not be completely accurate but that is what my knotmeter shows. Under full throttle I only get 3100 rpm. My Yanmar mechanic says my 2GM20F is good and that I should be getting at least 3400 rpm. So, next time I haul the prop is going to a propeller firm to be reset. From you comments I suspect you have something other than a prop problem to account for your slow speed.

 

[Dennis Oelrich]

Been there, done that

While I was in the middle of sea trials on a 1980 Hunter 30 I found that the boat would only do about 4.2K at 3200 RPM. The owner said that was normal however my guess was that hull speed should be about 6.2 or so. The yanmar seemed to run and sound fine. Before I had the boat hauled I called a prop shop and was told that to recommend a prop they needed to know the engine hp and rpm (Yanmar 2gm20@ 3400RPM), the gear ratio (2.6), and the prop diameter. When we hauled the boat we found a 13by10" two blade installed and the recommendation from the prop shop was a 13X13 three blade should do the trick. A new prop was delivered, installed and we returned to the slip at over 6K. I bought the boat.