Marine Forum

Smoking engine

catman

10 February 2006 09:51:53

Joined: 10 February 2006 09:50:13 | Posts: 1

I have recently bought a pre-owned 37 foot catamaran that I'm very happy with. The vessel is fitted with a pair of 18hp Yanmars that run very well. Engine clocks reflect 1900 hours of operating time. However, I have noted a significant amount of black smoke(from both motors)when revs are taken above 2800. This also deposits noticeable quantities of soot on the water. Any comments on the possible cause(s).

The S drives are fitted with two blade props. I am considering an upgrade to 3 blade props to improve manoeuvrability. Is this likely to give the desired results and where can I get the specs on the props I should use?

Re: Smoking engine

John

10 February 2006 09:58:01

Joined: 24 November 2005 13:48:22 | Posts: 5

Black smoke can be caused by:

Obstruction in the airflow
Dirty air filter
Defective turbocharger
High exhaust back pressure

Excessively high ambient air temperature

Overload
Rope around prop
Oversized propeller
Heavily fouled bottom
Excessive auxiliary equipment

Defective fuel injection

The best way to size a propeller is to have a propeller shop do it for you.