A few of our viewers asked me to explain just what a raw water system was and how it worked.
Raw water refers to the water that the boat is floating in.
It makes no difference whether it is salt or fresh, both are used to cool the engine. The process starts by drawing water into the engine through a seacock fitting and pumping it through the engine's water jacket and ports by way of a mechanical water pump. In a raw water system the water is drawn up through the seacock by the water pump. The water flows through the engine and directly out the exhaust. This cooler water absorbs heat from the engine to help keep it cool.