Re: [Amel] Re: C Drive Broken

Giovanni TESTA

Hi Danny,
I have some vibrations at 1800 rpm and I'm planning to check all trasmission system.
About flexible coupling I have new rubber wears as spare, with circular box , from Amel...and I'm planning to sail from Raiatea to Tonga...than to NZ !
So the question is : how did you check and replace yours ? Is it necessary to move the engine ? if yes how ?
thanks in advance
Gianni TESTA
sv EUTIKIA SM 428_2003
now CNI Raiatea

----- Original Message -----
From: Danny and Yvonne SIMMS
Sent: Wednesday, April 04, 2012 6:38 PM
Subject: Re: [Amel] Re: C Drive Broken

Hi Kent, I have to agree that the flexible coupling is an esential part of the train and cannot believe the mechanic relanced the rubber bushes with ceramic. Yes the rubber wears, (I replaced mine 18 months ago) but that wearing is a natural part of the job is is doing and does not indicate misalaignment as they, as well as allowing for any slight misalignment they take up the shock from every gear change and every acceleration and deacceleration..Think of the load that would be on the coupling driving the boat at full power into a strong wind and sea.
I had to replace mine in Neafu, Tonga where there was no chance of accessing parts. I tracked down some leaf spring rubber bushes at a truck parts supply shop and trimmed them to fit. They did the job until I was back in NZ and got the proper part.
SM 299 Ocean Pearl
New Zealand

From: Kent Robertson <>
To: "" <>
Sent: Thursday, 5 April 2012 4:26 AM
Subject: Re: [Amel] Re: C Drive Broken

Thanks, Craig, Richard, and Bill,
I'll forward your thoughts (with judicious editing) to my engine/mechanic guy. I'll be interested to see what he says. He's THE Volvo go-to guy for the Caribbean and they send him all over the world to work on mega yachts with Volvos. Seems like the only way to get really good advice on Amels is to go to an Amel service place of which there is only one in the western hemisphere. I guess the language barrier is tiresome for them as well as it is for me, but I find communicating with them difficult at best.

I'll take this opportunity to put a plug in for another Amel service site on the east coast. Is there any way we can influence Amel to take notice? As before, I'd recommend Deltaville Boatyard on the Chesapeake if they'd like to have suggestions.

I'll keep you abreast of the repair as it progresses, right now the procurement of parts is looking like it's going to be a problem. That language barrier thing. If I have parts manufactured here it may require a matching set of shafts and gears. We'll see.
1999 SM243
Currently Ponce, PR

From: sv Sangaris <>
Sent: Wednesday, April 4, 2012 11:54 AM
Subject: [Amel] Re: C Drive Broken

Hi Kent,
The unit you mention with the 4 rubber sleeves on the 4 steel pins is, indeed, the flexible coupling between your transmission and the "C" drive. It's a VETUS brand Type 6 (Google it - not too expensive). The Vetus specs allow for up to a 2 degree misalignment and it's also self-centering.

I've not heard of replacing the, duh, FLEXIBLE rubber sleeves with CERAMIC ones - every ceramic thinghy I've ever met is NOT Flexible. No wonder the shaft broke. Seems like one more example where an "expert" screwed up; making a flexible coupling rigid.

Btw, there is one other "flexible" component in your drive train and that's the "dampening plate" that couples the engine flywheel to the input shaft of the transmission. This one has stiff springs in the plane of the flywheel and absorbs shock loads from shifting gears or the prop hitting something.

Craig s/v "Sangaris" (year etc., irrelevant to this post.)

"Judy and Bill aboard SV BeBe" <yahoogroups@...> wrote:
> I do not know much about this, except that I know that you need a flexible fitting somewhere to absorb the shock when shifting from forward to reverse, and even neutral to forward...and especially with a self-trimming prop, like the Auto-Prop. A normal propeller does not give the shock that a self-trimming prop will. Your expert may have been correct if it was a normal fixed prop. I hate it when these experts do not know what they do not know!
> The only way you are going to tell, for some degree of certainty, is have a metallurgic test preformed on the broken shaft...and don't let a mechanic be your expert for this. Possibly the shaft was weak and removing the flexible fitting was all it took to break it.
> I know what you mean...I hate it when some "expert" tries to tell me that the original design is wrong. In my limited experience, when this happens, I have been better off running away from that "expert." I am guessing that "Le Capitaine" is(was) right 99% of the time.
> Good luck and I am sure that we all feel your pain.
> Bill
> BeBe, SM2k, #387
> Currently N Cyprus
> --- In, "Kent" <karkauai@> wrote:
> >
> > Thinking some more about the "shaft coupling" or "flexible coupling". I remember when the new engine was installed last year that the rubber fittings (4 of them that go on 4 steel pins perpendicular to the engine shaft) were worn. I believe that they are part of the coupling from the engine to the transmission. The engine mechanic replaced them with ceramic parts that he said would be better and last longer than the rubber ones. I'm wondering if this change might have made the "flexible" coupling a non-flexible one and contributed to the failure. Is there another flexible coupling between the transmission and the prop drive?
> >
> > Another note of interest is that the broken ends of the drive shaft appear to have discoloration everywhere except a 1 sq cm area near the middle of the shaft. The engine guy felt that this indicated that the shaft had mostly failed over quite a long time and that the final failure was due to that last 1 cm breaking.
> >
> > Thanks for your thoughts.
> > Kent
> > 1999 SM 243
> > Currently in Ponce, PR
> >
> >
> >
> > --- In, "sv Sangaris" <sangaris@> wrote:
> > >
> > > Hi Kent,
> > > Sounds like it (hopefully) could be the shaft coupling, rather than an internat gear failure in the "C" drive. Fairly easy to check out if you just loosen the 4 bolts holding the coupling together (assuming you've got a Vetus coupling.)
> > > Good luck & let us know the outcome.
> > > Craig s/v Sangaris; SN#68; Leros Greece
> > >
> >

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

Join to automatically receive all group messages.