Fueling the Conversation

IN CAPT. RICHARD THIEL’S SEPTEMBER POWER & PROPULSION COLUMN, “THE TRUTH BE TOLD,” he dispelled several common myths about marine diesel engines. We asked you for some lore that you’ve heard during your time on the water. Here are some of your questions and comments, and Capt. Thiel’s take on each.

Just read Capt. Thiel’s article on diesel engines. I have a 315-horsepower Yanmar. After starting the engine, I let it idle for 3 to 5 minutes because the alternator will not kick in until the engine reaches around 115 to 120 degrees. It stays around 12 volts until the engine reaches the magic temperature, then goes up to 13.5 and higher. I have a bow thruster and need to use it because of the close quarters of the adjoining docks. As the thruster takes considerable juice, I wait until the voltmeter shows the alternator is putting out 13.5 volts or more. I called Yanmar and the agent there advised that the alternator will not kick in until it reaches the magic number. Make any sense to you?

— Tom Harken 1999 Albin 28 TE, Sparty Ft. Myers Beach, Florida

combustion. After the start, I always immediately go to the transom to check for water exhaust, this insures your seawater impeller system is working. On start, your low-oil-pressure buzzer or combined-hightemperature alarm will sound briefly until oil pressure builds up. In my harbor, just 1300 rpm kept the boat at 5 knots and it was warmed up by the time I cleared the jetties to the breakwater.

— Doug Robertson 1988 Sundowner 32 Tug, Seeker

Oxnard, California