Re: Elongated hole on conical coupling


I do not know what the factory originally did on my boat.  Those bolts have been pulled out and reinstalled several times with the installation of new engine mounts, alignments and other maintenance procedures. If somebody was paying attention to details (and Harmonie's previous owners were very good at that) they replaced at least the washers, and likely the nuts and bolts each time. They may, or may not, have been put back in the original configuration.

I do not understand exactly what your local dealer is proposing to do, but there are a great many good solutions to keeping these connections tight.  There could be long arguments about which is the "best," but there are many solutions that I'd be happy with, probably including some I haven't seen before.  

Remember, pretty much every boat has a connection like this between prop shaft and transmission.  Keeping them connected is not a new problem, or one unique to the Amel drive train.  In fact, you could make a good argument that the Amel C-Drive presents a much easier problem because the loads are lower and more controlled than with a standard prop shaft.

If you put these bolts on your regular maintenance schedule and check them for tightness after the first 10 hours, and after that at least every 50 to 100 engine hours, you'll be good to go.

Bill Kinney
SM160, Harmonie
Annapolis, MD, USA

---In amelyachtowners@..., <svperegrinus@...> wrote :

Hello Craig and all others,

Many, many thanks for all the valuable input.

Regarding the possibility of the nuts coming loose, yesterday the Yanmar dealer told me they are creating "a washer" (via an outsourced turner).  I am sure there is a language barrier + my lack of mechanical engineering knowledge.

But if I understand correctly, this will be some sort of one disc that they will insert after the four nuts have been tightened, and this will prevent the four nuts from working themselves loose.

My main concern is that if the solution were so simple and obvious, why wouldn't the factory had implemented it?


SM2K #350 (2002)

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