Vibration @ 1,800 RPM

[SteveH290]

I recently purchased a 2000 Hunter 290. Before I purchased the boat, the research I found said there is a significant vibration when motoring at 1,800 RPM. My boat does exactly that. No vibration at lower or higher RPMs.

Any suggestions to minimize at around 1,800?

Thanks,
Steve

 

[Roddie]

My 2004 306 has a similar noise harmonics I am told (outside the boat) I am led to understand you should avoid operating in this area and there is nothing that can be done ???

 

[Steve Dion]

Most boats have this issue. Not at any specific RPM, but it is a fact of life. I think a two bladed prop is slightly worse than a 3 blade, but changing props will not necessarily get rid of it.

Assuming you have a 2GM, you should be cruising at 2500-2900 rpms.

 

[Warren Milberg]

My 1986 Yan 2GM20F also "vibrates" a bit at around the 1600 rpm range. I simply run the engine at higher rpms and don't worry about it.

 

[SteveH290]

I will do the same. Thanks.

 

[Robert 47]

My GMF20 has a vibration at idel only. Very annoying knock the PO says has been there since he purchased the boat in 1992. He never found it. I have never found it, and have almost taken the boat apart in the 5 years I have owned it. But you push the rpm up and it smooths out nicely. I have no problems at any rpm range on my engine. As mentioned above, it must be a "built in problem".
But you can check the obvious places: rudder shaft, motor mounts, engine thru shaft, cutlass bearing, prop mounted correctly or loose. I would also check to see if you have a fuel restriction in the supply line somewhere that would starve out at the range. Filters are cheap and easy to change. Good luck and let us know what you find if anything.