Is there supposed to be something in the engine hot water circuit that stops the temperature in the cylinder from reaching explosion levels?
I started using our hot water cylinder the other day for the first time in two years and since we have had the boat and the freshwater outlet blew off after motoring for a couple of hours. The engine temperature was sitting around it's normal 90degC. The boat became a bit of a steam room for he next half an hour while the remaining water boiled off.
I haven't tried exploring the water pipes to see if there is something in the circuit, like a temperature regulator that isn't working, but given this has happened I would kind of expect something to exist?