Exhaust Discharge Thru Transom

Ahoy BCC Sailors , has anyone else experienced a sooty transom ?

A fully loaded BCC can sit v low on it’s lines , and this causes the exhaust outlet to be lower too.

I found that eventhough I fitted a rubber , “flapper” on the exhaust outlet , that the exhaust carbon still sooted up the transom.

My remedy was to raise the exhaust port by 6" .

Now the stern wave, does not submerge the exhaust pipe while under full power, underway , and now I get a heap less carbon on the transom , to scrub off .

Has anyone else done the same ? and had beneficial results, too ?

Douglas , BCC Calliste 072

Hi Doug, I think what you did is a good move, if for no other reason than to prevent back pressure. However, I doubt if this is the reason for your sooty transom. I have a friend who is a master mechanic and he told me that the primary reason of the dirty stern is improperly burnt diesel. I have been using a diesel additive to clean injectors and provide a clean burn. Since I started using an additive several years ago, I no longer have any soot at all.



Iduna’s exhaust port is located about 1/3 up the transom’s freeboard from the waterline. The exhaust hose is connected to a Vetus gooseneck which is located just under the aft deck. The goosenecks lower part is attached to the exhaust port. The Vetus gooseneck acts as an anti-syphon device and is very effective. We do have some “blackening” on the tansom but this is mostly the result of the exhaust water splashing on the transom.