BOAT SPEED UNDER AUXILARY POWER

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Marguerite Becker

This may have been discussed before but we just took possession of our new 356 and would like some imput as to boat speed under auxilary power. We're turning 3800 rpm and it seems we're going at best 6 knots according to the GPS with no current or tide. We have a three blade Max Prop. And one other question - when we pull the throttle back to idle the engine shakes considerably. Anyone else have this condition? Thank you, Marguerite s/v can't decide on the name yet!
 
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Jeff Becker

I have the same problem.

Hey, Marguerite, checking the web site I see you're having the same problem I do. Oh, wait a minute, no wonder, it's the same boat! You want to go sailing tomorrow? Hopefully we'll get the problem fixed soon. What's for dinner? Love, Jeff
 
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Pete

engine shakes

as far as the engine shaking when you pull the throttle back to idle I would check that the engine idle speed is set corectly,it should be 800 to 850 rpm's. I would also caution about running the engine at 3800 rpm's. This is a 3gm30 engine and the max rpm is 3600. I suspect that maybe your tack is not reading corectly and have the dealer (since it is a new boat) calibrate the tach and verify it (there is a electronic gun that can measure rpm's of the pully or flywheel) If the tach is correct you may need to have the maxiprop pitch set as it could be underproped and this is why you are at such a high rpm and not at hull speed. Ask who ever installed the prop what the pitch was set at.You might want to check with Hunter to see what size and pitch they recomend for this model. Good Luck on your new boat !
 
Mar 21, 2004
2,175
Hunter 356 Cobb Island, MD
Same Problem - Fixed its the idle to low

Last November after having the 50 factory servicing done, week later wife and I took the boat out. I thought I had throw a blade or the engine was trying to jump out of the boat or we had one of the best vibrating beds on water. Fast check with Crazy Dave and he said the idle is to low and the rpm's are dropping to low. I adjusted the idle until the rpm's were 400 (I think). If I remember it was no fun bending over the engine to adjust. Happy Trails. Jim S/V Java
 
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Ivan Bekey

Engine fix, and caution

I also had the scary shakes problem. At sugestion of dealer I adjusted the idling up to to 800 rpm and it is as smooth as a baby's bottom since. The engine cannot tolerate anything slower. With regard to the speed, NEVER run the engine faster than 3400, and that for only short times during break in. Read your instruction manual--it says the same thing as wel as speed variations and durations during break-in. Craig at dealer (Norton's in Deltaville, VA, and the smartest engine man on Earth since Fulton) says that the engine will destroy itself rapidly at 3600 but can run all day at 3400 and will last 100,000 hours at 3200. I try to stay below 3400 all the time. Sounds as if the prop pitch is too small on your boat. Ivan
 
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