Maximum Cruising Speed under Power - Hunter 280

[MaryC]

I have a Hunter 280 with the larger engine I think it's the 19 HP. My daughter and I are currently on a trip from Grand Rivers, KY to Mobile., AL. I've been running the engine at 2500 rpm most of the way - and depending on current have been getting 4.7 knots as my maximum speed.

This next part of the trip will have some long places between anchorages and we need to get there before dark. I'm not sure if it's ok to run the engine a little harder to try and get a bit more speed. Is it OK to run at full throttle for 6 or 7 hours. Would this be bad for my engine? I sure don't want to risk breaking down - as this next area is also very remote.

I'd appreciate input on this.

Thanks,

Mary

 

[Ed Schenck]

Spped as measured where?

Mary, is this speed over groung(SOG) as measured by the GPS? I ask because 4.7 knots seems slow for 2500 rpm. If SOG and you are going against the current then that would be reasonable I think.

But so far as running the engine harder it should turn 3000 for six or seven years, forget hours. But if there is a bottom or prop or other problem you probably won't notice much of an improvement in speed. Have you tried 3000 to see the speed?

 

[MaryC]

Re: Spped as measured where?

I haven't tried 3000 as I wasn't sure how far it was ok to push it.

 

[Clark]

Mary, I believe max RPM for our engines is like 36-3800. We have a 'sweet spot' at ~2900 where most vibrations settle down (not butter smooth mind you) and it feels like it would run all day long. We do get hull speed (~6.5 K) at that RPM. Ed is spot on and many recommendations are that one should run at about 80% of max and that is GOOD for the engines.

Oh, one more thing. Don't expect the tachometer to be highly accurate; it could be reading off 100-200 rpm.

 

[s sauer]

Assuming you have a 2GM20F Yanmar, the max RPM should be about 3600 RPM. Typical cruising speed should be about 80% or 2880. and you should be seeing 6 to 6.7 knots thru the water. If not you may need to clean the bottom and/or clean the prop. It won't hurt the engine to run higher RPM, but you might back down to 2800 merely to conserve fuel.

 

[MaryC]

thanks everyone

This is great news. I will definitely push it up a bit. It would be great to get 6.5 knots. If I can't get her up to that (assuming the current is not a factor) I'll check the prop. I just had a bottom job about 3 months ago, so that should be ok.

I'll let you know how it goes. We were planning to travel today - but now thunderstorms are predicted so we're going hold tight until tomorrow.