Dear Boat Doctor,

I sail a Catalina 380 on Lake Michigan and it has a freshwater-cooled Westerbeke 42 engine. I use the engine basically to get in and out of the slip so I don’t run it a long time. I was doing some reading and learned that I am not supposed to baby the engine, that running it hard is good for it. I have been running the engine a little faster and for longer, but now I am nervous that I am running the engine too hard—the cooling temp was up to 185 degrees the other day. How am I supposed to run this engine?

Tom Sullivan
Escanaba, Michigan

Dear Tom,

There is a tendency for sailors to baby and unintentionally abuse their engines. A few bad practices are the quick, low-speed run to get out of the slip and the idle or low-speed charging session. A diesel engine likes to be run with a load and at operating speed. A loaded engine running at a reasonable speed will get to a proper temperature. Running at low temps can cause carbon buildup in the engine as well as not allowing the oil to heat up and “cook off” dissolved contaminants.

When you use the engine to get out of the slip, run it at speed for 20 minutes or so, at maybe 2,000 rpm. The normal operating temp for your boat is 170 to 190, so the temps you are seeing are just fine. If you need to charge underway, put the boat in gear and throttle up; you are burning the diesel so you might as well get some boat speed out of it, and your engine will thank you.