black rear end

[pcatterall]

After 2 weeks cruising in uk and using the engine a good deal we had a very dirty transom ( black exhaust deposit)
Cleaned it off and now after 3weeks on the french canals at 5 knots its back.

We are not burniong oil and my reading suggests that it must be unburnt diesel caused by a dirty filter ( will change) or lack of air into the engine compartment.

I cant actually see any smoke only the results!

The engine compartment is quite large but no vent as such only the few usuall holes here and there by default!
Is there a figure for the optimum vent size ( 4108) I am going to improve the sound proofing which may cover some of the odd holes so I need to consider airflow properly.
Vents with fans would be smaller but just another complication.
Engine is under hatches in centre cockpit boat.

Is a meter a worthwhile investment just to be sure that we are burning fuel efficiently.
Many thanks

 

[ostell]

Probably just particulate matter that is normal in diesel engines. Bit of plastic drainpipe into exhaust to extend a couple of inches seem to have helped the problem on my boat. 1 1/4 inch plastic pipe with tape round the end to give a good seal to the exhaust fitting.

Or you have been motoring a lot with the wind behind you.

 

[sailorman]

Redex in the fuel might also help