Transom Soot

[John J]

For those of you who posted earlier, I have heard back from Catalina and Westerbeke. Basically I got the same proposed solutions that Gordon shared. Engine load, injectors, prop pitch, clean fuel, tach readings......Mechanic on board this week (or so the dealer tells me again) Will post if he finds anything out. (Catalina 310)

 

[Jon W]

Same Problem

John,I thought I'd mention that my 310 also has a sooty transom. It’s usually not too bad unless I really start pushing hull speed (more than 6.4 knots) top speed is 7.1 knots.I'm curious what prop you have, and what cruise speed and rpm you use.I initially thought it was my setup causing the problem. An AutoProp, Universal M25XPB, and 6.4 knots at 1800 rpm (ballpark calibration on the tach which reads 1000 idle and 2700 rpm full throttle in gear, 3000 rpm in neutral). This is my second Autoprop. We went down slightly to 15.5-inch diameter to give 200 more rpm's at full throttle. The Autoprop people swear it's not too large, and the rpm's are characteristic of the self pitching blades.In a way I am relieved that the soot is not unique to my boat. I'd appreciate your comments.BTW, The sooty condition may be more noticable on C310's than some other boats due to the pristine white hull, and the design of the transom.

 

[John J]

Sooty Transom

Thanks JonYour speed and RPM's are vastly superior to what I am getting. (@1800 about 4.5 knots, @2400 Mid 5's) Being under warranty makes this a little easier. I also had a dripless shaft installed and I wonder if it is over tightened and causing undue load. I'll let you know what I find. My soot MUST be cleaned off after running for only 10 minutes. It is pretty heavy and I don't want to damage the gelcoat.Thanks for the infoJohn

 

[John Iurka]

Sooty 'Transom

Diesel Engines and white boats, you just can't avoid a sooty deposit on your beutiful white rear end. Even with constant polishing, and washing, i have a deposit after only 1-2 hours under power

 

[Steve Dion]

If no resutls.....

you guys may want to try a mixture of Soy Diesel in your tank. One of the properties of the product is that it helps eliminate soot. I would recommend that you try a 25-30% mixture in your fuel and see if it helps.

 

[Gary Groth]

soot on trasom

I have come to the conclusion that it is poor exhaust location that has caused my soot problem on my 93, 36 Cat. Every Catalina in my marina has soot on the transom after motoring and everyone of them squats while motoring and the exhaust ends up under water where the diesel residue mixes with the water and ends up on the transom. Next time check out a boat with an exhaust port well above the water, I bet you won't is nearly as much soot. I am moving my exhaust opeing up so it will no longer be in the water while motoring. I've been told there is not a problem with back wash as long as you keep the loop above the exhaust. Anybody ever tried this?