A short time ago there was a discussion about expected fuel consumption which interested me as I was planning a long sail/motor from CT to VA. On Sun. Sept. 9 we began a trip from Norwalk CT to Hampton, VA arriving at VA on Friday Sept. 14 after a 28+ hour last day sail/motor from Cape May, NJ against swells and 18 to 25 knot winds.
In order to maintain speed and arrive Friday I ran the engine for almost the entire trip while underway. The wind was usually on our nose but when the direction was favorable the wind speed was not sufficient to keep the boat speed above 5kts necessitating running the engine.
During the trip I experienced consumption of about 1gal per hour when running the engine 2400 to 2500 rpm. I was able to maintain a speed of between 5.3 to 6.0 kts, often against 2ft to 4ft swells .
When I held the rpm to 2400 I noticed light colored smoke coming from the exhaust. At 2000 and below the smoke disapeared.
In earlier posts it has been established that the prop is overpitched, this will be corrected now that the boat is in her new home.
My questions--
+ Is the high fuel consumption due to the overpitch?
+ Is the smoke unburned fuel due to the engine laboring to turn the overpitched prop at the high rpm?
As always any thoughts and advice will be appreciated.
The light smoke that you see is almost definately unburnt fuel. Any engine that is heavily loaded (and is kept in this condition for a long time) will use more fuel than an engine that is running free.
I am sure that when your prop is correctly pitched, you will see an improvement in fuel consumption.
I will continue to operate for a while with the present prop config and whe hauled later this year, I will repitch and look forward to better engine speed and lower fuel consumption.
