CD 28 Farymann A30 flexible propeller shaft coupler.

[Seaweed2]

Beautiful day for sailing. Brought wife and daughter up to the boat for a nice sail and when we went to back away from the dock the boat didn't seem to move with any enthusiasm. It felt like it was shifting, and even made some noises like that was happening, but no mechanical propulsion. Got it tied back up at the dock and noticed that the coupler from the transmission to the propeller shaft had separated. It consists of two flat 1/4 inch thick metal discs at each end with a likely vulcanized thick rubber bushing sandwiched in the middle. The rubber had torn from the propeller shaft disc end. After much work (thankfully my daughter was small enough to contort into the compartment) we freed up the disc that did not have the rubber attached. Much internet searching and many phone calls later and I have no good prospects. I saw some old threads from back in 2009 where someone was looking for one of these and they were hard to find then. Not to mention, the price was over $400! I have a call into 3M and am waiting for sales rep to get back in touch. Thinking maybe there is some mighty powerful glue that will hold it until the other end separates! Farymann closed their doors last Christmas and went out of business. Any ideas?

[Frenchy]

I hope you can find a replacement spacer- that would be the easiest solution. But if not, I'd suggest unbolting the rubber/flange piece from the transmission drive and see what's there. Many drive flanges
(including mine) have four holes on a 3-1/4" bolt hole circle. That makes the holes about 2.3" apart.
You could purchase a new prop shaft flange to match what's on the transmission and have a new, longer prop shaft
made. The cost won't be too far away from the $400 you mentioned. A propeller shop would fabricate and assemble
the whole thing. If desired, you could add a new drivesaver between the flanges. They're about 1-1/4" thick, so you would still need to have a new prop shaft made. Good luck - Jean

[Seaweed2]

Thanks for the reply. That might just be the best idea yet. I saw those drivesavers in my searches and they look like they would help dampen some of the torques from transmission to shaft. I certainly do learn an awful lot from working on boats! I am also looking into finding someone who vulcanizes rubber with(to) steel. All interesting stuff.

[Keith]

Just had a thought that might work for you. Bolt the two flanges together with the rubber in-between. Remove both flanges, drill and countersink the trani mounted flange (drill through the rubber at the same time), drill the shaft flange to match. Get 4 flathead machine bolts and 8 nuts. Probably have to use jam nuts on the bolts because of the rubber compression.

If that doesn't work (I think it will) you could then replace the rubber section with a solid piece of round stock with the 4 holes drill through.

Food for thought.

Keith

[Seaweed2]

Hmm. Now you've got me thinking. Perhaps tapping the disc on one end and countersinking on the other end might work. Then bolting them both back up. The 'disc' the rubber attaches to bolts up flush to the flange on the propeller shaft and also to the transmission output flange so there is little room for any bolt parts to be sticking out. (Thinking out loud)
Aha! Now I think I see what you mean. Countersink at the transmission plate and drill right through the propeller plate AND the propeller flange, genius!!! Or actually bolt all the way through from the propeller shaft to the threads on the transmission flange. If I throw some good glue on the rubber that will help hold it all in place too. What I still don't get is why I would need 8 nuts?
And the whole solid rubber stock idea may even be better. Thanks so much for the tips! Sometimes it helps to get a different perspective especially since it all seems so plausible now. I am invigorated!

[Frenchy]

Be careful. Alignment of the prop flange and transmission flange is important as well as having the faces of the
two flanges relatively parallel. Most flanges have a either a boss or a recess that mates with the opposing flange
to maintain axial alignment.
If not aligned, you could get excess vibration or damage the transmission. - Jean

[Keith]

When you tighten the nuts down the rubber will compress and the nuts will never stay tight. Jam nuts will solve that problem.