Has anyone else has run into this problem with their boat's hot water
heater?

The problem is that once the water is heated up by the hot engine
coolant, the 110 v. electric water heating stops working, because a
thermal overload breaker on the heater trips.

The heater runs on engine heat or 110 v. The thermostat on the heater
includes a thermal breaker that trips when the tank goes above 170
degrees. The normal operating temperature of my Volvo diesel engines
is 175-180 degrees.

So eventually the engine coolant heats the water above 170, and the
thermal breaker pops. Now the heater won't work on 110 v. until the
thermal breaker is reset. (This requires disassembling the panel on
the heater to get to the breaker.)

Does anyone else run into this problem? Any ideas for a workaround?

The heater is a SureStor SS-12M made by Advanced Heat Transfer.