Prop coupling

[simonn]

Do i need a flexible/Plastic coupling between gearbox and propshaft?,All my other yachts had one but lastest one has`nt,Any advice? Yacht is malo 34 Engine volvo 2003t 43hp. Thanks.

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[boatless]

Not neccesarily, even though the plastic ones look soft, they really don't reduce transmitted vibration very much. It just means that adjusting engine/gearbox mounts is more important. Something like the AquaDrive allows the engine to be way out of line before it gets upset. Malo wouldn't cut a corner like that. There will be more flexibility in the stern gland than there was in the old days - which allows greater tolerance. Just check that the shaft is relatively easy to turn from time to time.

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[VicMallows]

If you can fit an AquaDrive (or similar) great. The thrust is then taken on the bulhead mounting rather than the gearbox, as well as any load due to misalignment. Unfortunately I don't have enough room (Sadler 29).

The best answer is simply to ensure VERY acurate prop-to-gearbox alignment...you are talking about your thinnest feeler-gauge at the coupling; and check it every year, especially on a new boat.

I cannot reconcile the idea of a flexible (plastic) unsuported coupling with the usual flexibly coupled stern tube. What do others think?

Vic

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[boatless]

Well, the flexi plastic ones aren't really very flexible, look like tupperware, but nothing like it when you actually try to bend them. Suppose that they are a poor form of insurance against mis-alignment.

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[steve6367]

They are very hard and still require accurate alignment. Provide an easy way to check alignment and allow you to isolate the prop from the electrical system though.........

Also got a rope around the prop last summer and it had enough give to prevent damage as the shaft was pulled backwards.

Not required though.


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