Engine Cooling Systems

Diesel engines may be set up for Heat Exchanger or Keel Cooling. Both systems are satisfactory for trawler yachts.

Heat Exchanger systems involve pumping sea water through engine mounted jacket water coolers, the gear box cooler and intercoolers if fitted. The seawater is thereafter passed overboard. The objection to this system is that the sea intakes can become blocked, resulting in overheating, and a separate seawater circulating pump has to be fitted. This systems main advantage is that all components are installed inboard. All heat exchanger cooled engines should have two sea intakes widely separated and connected with a cross main.

In Keel Cooler systems no seawater enters the vessel; instead the engines fresh water circuit is piped through an external hull mounted propriety cooler or a weld on “Limpet” cooling system. The engines jacket water pump is used to circulate the fresh water through the circuit. This method has the merit of simplicity and is often the chosen method for trawler yachts. There is a risk that the external coolers may be crushed or develop leaks which of course cannot be fixed without slipping.