Experience with Aqua or Python Drive

[Frankklose]

I would like to hear from somebody who has installed one of these flexible shaft couplings.
I own a Jeanneau Rush and she has a fairly noisy engine. I have already isolated the engine room with the noise insulation material of Haylyard. It helped but didn’t solve the problem. Also different engine mounts have been used. The engine is a 20 HP 2 Cylinder Ruggerini.
Last week the gearbox went defect, and I replaced it with a shorter gearbox and got now the space to fit one of these couplings. I am a little bit worried since the coupling is directly mounted to hull with small rubber gaskets that the problem which I like to solve could become even bigger. I have read over the years the propaganda of both manufactures, but never have heard from somebody who actually builds it in his boat.
The shaft alignment is as best as it could be. I believe the engine mount has not enough mass and therefore the hull resonates like a guitar body.

 

[penfold]

The Aquadrive acts as a thrust bearing, so it has to be rigidly mounted to the hull. The engine is decoupled from the prop shaft by a pair of constant velocity joints, just like you get on car drive shafts, which allows softer engine mounts to be used.

A friend of ours had one fitted to his Halmatic 29 with a VolvoPenta 2002 a few years ago, and the difference was very noticable. At low revs before fitting the Aquadrive, there was significant vibration in the cockpit and the lifelines would flap up and down at their harmonic freq. After fitting, there was very few vibes, and no flappy lifelines. the other problem area had been at high revs(2800-3000rpm) it was very unpleasant in the cockpit with the vibration, to the extent that the owner wouldn't maintain those revs for long, nor go any faster. After fitting, the full rev range of the engine could be used without rendering the cockpit uninhabitable. If you do a lot of motoring I would recommend one. The only caveat I have is; don't look at the engine when it's idling, as the softer mounts allow it to dance the watusi around the engine space. Alarming to the uninitiated, but perfectly natural to what is second cousin to a cement mixer engine.

HTH
Cheers,
David