Marine Cooling Systems and Heat Exchangers

What is the main engine cooling system?

Marine Cooling Systems and Heat Exchangers

Marine engines, like automotive engines, are cooled by passing water through the engine block. Marine engines are unique in that they have two types of cooling systems. The typical raw water system and the fresh water cooling system.

Raw Water Cooling Systems

Raw water cooling systems draw water from outside the boat (seawater or lake water). Water is pumped from the source to the engine block, where the engine circulation pump drives the raw water through the engine block and out the exhaust. Raw water cooling systems are relatively simple and are the basic cooling system for most marine engines. In most situations, the raw water pump is located within the outdrive. The raw water pump on larger engines and inboard engines is positioned within the boat and is powered by a v-belt or directly from the crankshaft. There are hidden dangers that might mount over time, requiring you to spend a lot of money on repairs. The concern is utilizing salt water as a coolant in your engine. Salt water can be quite caustic. Flowing salt water through your engine block and exhaust manifolds will cause catastrophic corrosion that will go unnoticed until your engine or exhaust manifolds collapse.

In general, marine engines cooled with raw water, particularly those that use salt water, have a lower life duration than marine engines cooled with a closed cooling system.

Fresh Water Systems with Heat Exchangers and Keel Cooled Systems

Fresh water cooling systems, often known as closed cooling systems, are available in a variety of configurations. The most popular form employs a Heat Exchanger, which acts similarly to the radiator in your car. Coolant (antifreeze) is cycled through one side of the heat exchanger and is cooled by raw water that travels through the other side. The engine coolant is then recirculated back into the engine. The raw water is evacuated from the boat through the exhaust. A Keel Cooler is another sort of frequent closed cooling system. This is accomplished by without using a heat exchanger. Instead of sending raw water into the vessel's heat exchanger, where it cools the coolant, the coolant is routed through pipes or aluminum extrusions on the exterior of the hull, where the surrounding water (lake or ocean water) cools the coolant before it is put back into the engine. The use of keel coolers eliminates the requirement for a heat exchanger, raw water pump, and other components required for pumping raw water into the heat exchanger.