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Old 26-06-2021, 03:53   #16
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Re: Engine Thumping when Sailing

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Originally Posted by chasfgr View Post
Ouch,
Bent propshaft and if you're still going, new engine beerers and mounts.


Depends on engine revs when you tangled but may-be a bent crank.
Needs competent, on-the-spot diagnosis, not the musings of several well-meaning amateurs


A bent prop shaft would be pretty special seeing as it’s a sail drive. And a bent crank would be amazing since the shaking is only apparent with the engine off and the boat under sail.
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Old 26-06-2021, 04:26   #17
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Re: Engine Thumping when Sailing

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Originally Posted by UFO View Post
Also just to clarify, the thumping is pretty violent and very noisy - You can actually see the engine move.
If you can see the engine move, then it is probably the bedding of the motor mounts.

Careful, things could get bad real quick
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Old 26-06-2021, 05:59   #18
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Re: Engine Thumping when Sailing

A weird problem.

As well as the good suggestions you have received so far, it pays to think outside the box with strange symptoms.

Is there any chance that in choppy conditions a poor contact is momentarily engaging the starter motor? This will cause the engine to twist.
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Old 26-06-2021, 15:38   #19
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Re: Engine Thumping when Sailing

It would be worthwhile to check the shift control cable for correct adjustment and more importantly, the slack movement at the Saildrive shift lever. Some cat installations have very long cables that eventually allow some free movement of the lever. On an SD 50 the movement angle of that lever is critical. If the cone clutch is engaging and quickly disengaging the damage to the drive plate will eventually be terminal.
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