Engine Systems

Chris Riley by Chris Riley Updated on August 21, 2019. In nauticalknowhow

Cooling – Boat motors are not equipped with radiators as cars are, but still must somehow dissipate the heat generated by the friction of the moving parts. The two most popular cooling systems are the raw water system and the enclosed or fresh water cooling system.

The raw water system simply takes water from the body surrounding the boat, pumps it through the engine to draw out the generated heat and discharges the heated water through the exhaust system. This discharge has two benefits. It cools the exhaust and also muffles the sound of the exhaust.

An enclosed system has the same general configuration as the raw water system. However, in the enclosed system a small tank containing anti-freeze is added to the engine and this “fresh” water cools the engine parts. This liquid is then passed through a heat exchanger where its heat is dissipated through a series of tubes which are surrounded by the cooler raw water. This same raw water absorbs the heat of the fresh water and then is pumped out the exhaust as in the raw water system. The advantage of the fresh water or enclosed system is that the engine parts are not exposed to the surrounding potentially contaminated water. This is especially useful when operating in salt water.

Make sure when you initially start your vessel that water is being discharged from the exhaust system. This indicates that the cooling system is operational. DO NOT START THE ENGINE WITHOUT WATER BEING SUPPLIED TO THE COOLING SYSTEM. The impeller will burn out very rapidly without water to cool and lubricate it and you risk the possibility of the engine seizing because of overheating.

Electrical – The most common cause of boat breakdowns is electrical. By the nature of what a boat does and how it does it, it is a floating corrosion pit. This is especially true when operating in salt water. You should keep all electrical systems clean and corrosion free by frequent inspection. Clean battery terminals, electrical connectors, etc. and spray them with a corrosion retarding agent such as CRC or WD 40.

Fuel – Fuel systems are comprised of one or more tanks, valves, lines, pumps and filters. Each of these elements, if left unserviced, can be potentially hazardous. Check your tank often for potential corrosion which could cause leakage. Inspect the shutoff valves, lines, and pumps periodically for corrosion or wear. Check and change filters frequently in order to be assured of clean fuel entering your engine.

The most important tool you have to diagnose problems in the fuel system is your nose. Do the “sniff test” each time you board your vessel. If you smell fuel – find the problem.

Oil and Filters – Just as it is important in your car to keep the oil and oil filters clean, the same holds true in your boat’s engine. Every three hundred hours, or a least once each season, change the oil and filter on your marine engine.

Other tips – Prepare a safety checklist as a reminder of items which may require service, maintenance or simply a periodic check. On the following pages you will find a generic checklist which can be modified for your particular vessel.




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