Re: [Amel Yacht Owners] Bad Vibration in the prop drive shaft

Olivier Beaute

Hi Bill (It's all good),

the 1997 SM were not equipped with hydraulic gearboxes, and therefore don't have shaft brakes.
When the engine was replaced, what kind of gearbox was installed? Mechanic or hydraulic?

To start with the beginning, as we say in France, did someone dive to check if anything was caught in the prop?
As you mention, with engine off, throttle in neutral (and if you don't have a shaft brake system), your prop turns because of the water flow. If a piece of fishing net is caught in the prop, it turns with vibrations.
If a bearing of one blade of the AUTOPROP is seized, it will also turn with vibrations.In my opinion, the problem has nothing to do with the diesel engine condition.

In light winds as they had today, your crew should go diving and inspect the prop.
Do you know if, when the prop shakes the boat, the shaft that can be seen in the engine room turns also?

Good luck.


On Friday, April 24, 2015 7:19 PM, "seafeverofcuan@... [amelyachtowners]" wrote:

      Gear box fluid, transmission nuts and bolts at the coupler, engine bolts where they fit to the angle iron frame and the engine mounts themselves,all need checked.
The G5 prop is not normal for a Super Maramu and it needs serviced more regularly than the H6.
Brompton told me this only two months ago.
The worst vibrations that I ever experienced turned out to be a sized gearbox due to the transmission heat exchanger failing and dumping the fluid, but the vibrations occurred  only when the gearbox was engaged with the engine running.
It is really important to find out when the 110 hp Yanmar was fitted did they retain/install a shaft brake which will rule the prop in or out.
Sorry this reply is a bit tardy but anyone of the above could be part of your problem.
Good luck.
Trevor Lusty
Seafever of Cuan
SM425 Redline
For Sale
In Mexico

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