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Old 11-01-2015, 09:41 AM   #8
Shoalwaters
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City: Rodney Bay Lagoon
Vessel Name: "Dragon Lady"
Vessel Model: DeFever 41
Join Date: Feb 2008
Posts: 681
Thanks to all for the input.

Barnacle: The water injection port is hidden behind the down pipe in the second pic. See the pink arrow.

Ski and David: I was/am concerned about the even spread of water in the jacket and quite expected a dry/hot spot on the side opposite to the water inlet. However, so far so good. I can confortably put my hand on the exposed stainless bit just above the blue hump-hose with the engines at idle and at low throttle settings. Thus the jacket seems to be running full. I am concerned about how well exhaust and sea water mix at higher revs. I don't want un-cooled exhaust gas hitting the blue elbow. I will be doing some hand-on-elbow tests while someone else drives the boat. I have some grounds for hope as the new mixer and the old Yanmar one have much the same dimensions and lack of restriction. Also the water inlet hose and the jacket have much the same cross-section, so if one runs full the other should too (nice theory eh?).

David: Yes, both turbos had some corrosion on the dirty side. I don't understand exactly why, as they are some 5" above the water-line and I have never been in a situation where water was being driven back into the transom. Perhaps because the Yanmar mixers allowed seawater so close to the turbo outlets - I don't know. Fortunately I caught it in time. Whatever the cause, I feel comfortable I can prevent its recurrence with the new arrangement.

I will give serious consideration to shortening the muffler outlet hose. Meanwhile I take some comfort from the fact that water being pushed into the transom ports has to rise some 12" before it can flow into the muffler.

Xs: Likewise I will give further thought to supporting the turbo - I had considered this when putting it all together. The hump-hose is where it is to isolate the turbo from the rest of the exhaust system.
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