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Post by offshore on Sept 17, 2009 1:19:15 GMT
Hi
We slipped our 18 Month old 36i for the first time yesterday and the prop shaft is badly pitted inside the stern gland, inside the cutlass bearing and inside the prop. It looks like electrolysis but the anode is still in reasonable condition. Does anyone have any thoughts on what could cause this. Boat in kept in a marina pen with mains connected. Prop is a slipstream stainless steel folding 3 blade.
Regards
Barry
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Post by MalcolmP on Sept 17, 2009 21:16:47 GMT
Barry
was it a shaft anode? To work the anode MUST make a good electrical and mechanical connection with the parts being protected - and also be within "line of sight" and not much more than 2 feet apart
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Post by offshore on Sept 17, 2009 22:59:40 GMT
Hi
Shaft anode between the cutlass and stern gland. Anode was about 20% gone. Shaft had been treated with propspeed antifouling.
Barry
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Post by electricmonk on Nov 6, 2009 9:40:19 GMT
Barry, Yours is the third case I have heard of this year, including mine. The issue on yours is the stainless prop its a superior steel to the shaft so the shaft becomes the anode. The problem is Jeanneau shafts are not "real" stainless (the scrapper refused, after testing it, to accept my old shaft as stainless. A common mallady on french boats apparently). Fitting Anodes wont help because of the proximity of the stainless prop to the non stainless shaft, I suggest you remove the prop as a matter of urgency and inspect the taper for crevice corrosion. The only solution is to change the shaft for a REAL stainless or "Duplex" example.
Cheers
David
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Post by Zanshin on Nov 9, 2009 12:25:36 GMT
Add one more case for my 49DS, the surveyor was surprised at the pitting as well, despite what looked like adequate electrical protection. He stated that it was most likely inferior quality steel.
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Post by offshore on Nov 9, 2009 23:31:05 GMT
Hi David
We took the prop off when we saw the pitting and the the taper was so bad the prop was starting to rock on the shaft. So we had a local engineering company make up a new shaft while the boat was out of the water. They said the old shaft was rubbish steel and not truely stainless. The scary thing was that this all happened in about 9 months since the prop was fitted. Sent the old shaft to the local Jenneau agent but so far no joy.
Barry
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