Black water from exhaust at full throttle?

[JAYEL]

Sailing craft have a max hull speed through the water, reducing as the hull gets fouled up, so consequently your engine can only push it along at that speed, even if you open up the throttle even more. Result black soot , unburnt diesel, mixed in with the exhaust water. throtle back a tad and it reduces. Look back from the stern and you will see a trail of soot in your wake. There is absolutely nothing wrong with the engine, your hull could do with a scrub off.

 

[Anonymous]

Sailing craft have a max hull speed through the water, reducing as the hull gets fouled up, so consequently your engine can only push it along at that speed, even if you open up the throttle even more. Result black soot , unburnt diesel, mixed in with the exhaust water. throtle back a tad and it reduces. Look back from the stern and you will see a trail of soot in your wake. There is absolutely nothing wrong with the engine, your hull could do with a scrub off.

I've never had a "trail of soot" in my wake and my previous boat was a Centaur with the original MD11C! The present one is a modern 1999 110hp Yanmar, and that doesn't leave a trail of soot, either.

 

[Boeingdr]

Thanks for all the replies.
I will investigate further next week when I next visit the boat. I am suspecting prop/hull fouling to be the cause from what I have read so far.

 

[Stork_III]

Have just had an exactly similar problem (VP2020B). Exhaust elbow was close to blocked, only 7mm dia free hole. Elbow fractured during cleaning, new elbow, problem gone.

 

[capt_courageous]

Hi Boeingdr. When the engine is producing this black exhaust remove the oil filler cap and see if smoke come out. If it does it is bad news. If it does not then try what the others suggest.