Engine exhaust hull fitting and copper water lines


John Clark
 

When I bought my SM last December the surveyor caught evidence of a small water leak under the engine exhaust hose where it is attached to the hull.  He was deeply concerned that the hose was failing and exhaust fumes could be dangerous.  We didn’t see and significant water or fumes.   I bought a new hose, but the job kept getting postponed.  I’m now at a sheltered marina with almost no wave action and the temperature is perfect this week so I thought this was a great opportunity to eliminate that one job I have been dreading.

 

 

As we know the exhaust on the Amels is a bit funky.  On my boat the hose does not attach directly to the hull.  In fact at the hull there is nothing to clamp onto…at least not that I can see so far.  What I have is a stainless steel insert that fits snugly into a fiberglass stub at the waterline.  There is no flapper valve inside this insert.  The exhaust hose goes inside the wider end of the insert which is siliconed and pushed into the hull fitting.  My hull fitting/hose/insert were all coated in silicone.   To remove the hose I simply disconnected the rope hangers and pulled.  It was a good pull, but not super hard and the hose and insert disconnected from the hull.  On deck I did the same to remove the inert from the hose.    I am going to look into fabricating a brace to lock that hose/insert in place better than the rope hanger set up.

I found the insert had a small patch of pitting type of corrosion and was the source of the leak. The hose was also in poor condition as the surveyor suspected, I was able to tear it by hand. 

 

My vessel was originally delivered from Amel with a Perkins engine, but she was repowered with a TMD 22 by the original owner many years ago.  I have read here that Volvo recommends a 90mm exhaust hose for the TMD22 instead of the 75mm that was used on the Perkins.  I had 90mm hose so I think the insert, I found was the method used during the repower to increase the hose size.  I am repairing the insert and will reinstall it with the new hose.  I attached photos so others with early hull numbers can see what is hidden in that aft corner.

 

The concern I have now is the two fresh water lines that run under the exhaust fitting.  They are copper and where the sea water leak occurred, there is flaky blue corrosion.  Does anyone have any suggestions on how to address the copper corrosion without replacing the lines?   I don’t want to cut the lines because they are in one of the hardest places to access, and not someplace I want to bring a soldering torch.  I am hoping someone knows some sort of chemical treatment to stop the corrosion and protect the lines. 


                      Regards,  John


John Clark

SV Annie  SM 37

Morehead City


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