Capt. Dan wrote:

Thanks for your replies. I have not done the thermostats yet, but
will be doing them this week. This last trip was the first since I
went through both engines cooling systems. Thanks again.

Hang on a minute ... Chuck and I were talking about a raw water cooled
engine, one which is cooled directly by seawater. If your engine uses a
heat exchanger to remove heat from the engine's freshwater coolant loop
then follow the manufacturer's recommendations.

Rick