Black Soot On Transom

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kloudie1

kloudie1

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Nov 6, 2006
10,100
Hunter 34 Mandeville Louisiana
We were sailing last spring on South River around Thomas Point Light on the Chesapeake and noticed a very nice looking traditional 30 something foot boat.. We admired, and when we got astern of him, we noticed something dragging in the water .. There was a piece of what looked like clothes dryer vent hose about 6-8 feet long dragging behind. They’d clamped it onto the exhaust outlet so the engine soot would not blacken the stern of the boat.. It was … uuuuhhhh.. interesting looking (large pipe flouncing about in the waves, smoking profusely from the end). I wondered if any of you guys from there had seen him??.. Just curious.. Seemed like a cheap way to avoid having to do work on the engine!?
 
Scott T-Bird

Scott T-Bird

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Oct 26, 2008
6,295
Catalina 320 Barnegat, NJ
I've noticed that it is very hard to clean the transom

The soot just seems to rub into the wax. I had a great looking transom at the beginning of the season. From the very first start-up, soot began collecting.
 
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Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
This is just a method of evading the real problem. There are several reasons that this is occuring. Could be the prop, mixing elbow, crap on the prop/hull etc.

This takes it toll on the engine/drive train, so as the commercial said, "pay me now or pay me later".
 
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Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
If you clean the transom and condition the gel coat with a high quality product makes cleaning up the transom much easier. I have used the Island Girl products and found that this makes the clean up easier to deal with.

This is a common problem when running the engine at high RPM for extended periods of time. It also happens when the vessel is over propped or some of the other problems.
 
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ChuckThomas

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Apr 24, 2006
194
Hunter 33_77-83 Mandeville LA
i saw the same thing down in hopedale last year on an oyster boat. they claimed it to be a prototype jet propulsion. looked fast.
 
Cruisin30MKIII

Cruisin30MKIII

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Oct 16, 2005
91
Catalina 30 MKIII Mantoloking Shores NJ
My understanding of the problem is that the silicone found in most waxes, attracts the soot from the engine. So, the real remedy is to use a good quality wax that does not contain silicone.
 
Scott T-Bird

Scott T-Bird

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Oct 26, 2008
6,295
Catalina 320 Barnegat, NJ
I use Collinite's No 885 Fleetwax which I thought was one of the best. The soot sticks and rubs into it with no problem. I wouldn't even say that I have a lot of soot when I'm underway and I cleaned the mixing elbow this year. The soot I notice occurs when I first turn the engine over. Once it is spitting water, I don't notice a lot, but I've noticed that just the start-up contributes the most significant build-up of soot into the wax. If I run at 2200 rpm, the exhaust stays consistently above water and I don't have any noticable black smoke. When I run at 2500 rpm, the boat squats to the point where the exhaust is underwater and black smoke is noticable. At that point, the soot collects on the transom because the exhaust can't escape due to the water level. I can't consider our use prolonged since I rarely run the engine for even half an hour. I would have to circle the lake several times for what most of you consider prolonged running!
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,054
Catalina 34 224 Maple Bay, BC, Canada
Scott, you're right, Fleetwax "collects" black soot. Any good wax will. My engine runs fine, I still get some soot.

This is NORMAL.

I clean it off when I'm in the dinghy and find the time. Our stern is out when we dock, so I never see it!
 
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