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Winterizing Your Boat

Posted by on October 31, 2011

By carefully winterizing a boat’s drive system, you can save yourself thousands of dollars in repairs and the frustration of poor performance in the spring. Follow these steps to winterizing your boat’s drive system, and when warm weather arrives once again you will be out on the water in no time.

Change the Engine and Drive Train Oil

After running your boat all summer, it’s likely that water, acids and other byproducts have built up. It’s important to change the oil to prevent corrosion and excessive wear which can lead to loss of power, poor fuel economy or engine failure. Use a manual or electric oil changing system to make draining the oil easier, then add new oil according to the manufacturer’s specifications. Run the engine to circulate the oil through the system. At the same time you change the oil, be sure to change the oil filter. Change the oil in transmission or the outboard’s lower unit as well.

Add Antifreeze to an Inboard Cooling Systems

To protect the engine against damage from freezing, run antifreeze through the engine. For the best protection, drain as much water as possible and use a marine engine grade antifreeze – either one rated to -60 degrees or -100 degrees. Do not dilute the antifreeze or it will not perform correctly, which can be costly to you.

Inboards: Before adding antifreeze, start the engines to warm them up. After the engines are warm, close the seacock and open the strainer to flush the water. Finally, add the antifreeze. For smaller inboard motors, using a flush kit can make it easier to get the antifreeze into the motor. For larger inboards, one way is to start the engine and quickly pour the antifreeze in while it’s run

ning. Do not let the engine run for more than a few seconds without antifreeze. This method usually works best with 2 people, but if it’s only you, try disconnecting the cooling hose from the thru-hull, and placing it in a large bucket filled with antifreeze and run the engine. Add the antifreeze until you see it come out of the exhaust.

Outboards: Purchase a winterizing kit from your local marine supply store that contains a bucket, hose and fittings. Connect the hose and fittings and use them to suck the antifreeze out of the bucket and into the engine.

Fog the Engine Cylinders

To protect the inside of the engine until spring, you must fog the engine to protect its moving parts. You can spray them into the carburetor while the engine is running or apply it through spark plugs holes while the engine is turned over. Consult the engine’s manual, a mechanic or the manufacturer to find out which method to use for your engine.


Treat the Fuel System

Experts disagree on the best method for winterizing a boat’s fuel system. One method is to empty the fuel tank completely, which is extremely difficult. The second method, generally preferred by boaters, is to empty the fuel tank as much as possible and then refill it to leave as little room as possible. Once the tank is full, treat the fuel with a with a biocide (for diesels) or a stabilizer (for all engines). After adding it to the fuel, run the engine for 10 minutes or so to be sure stabilized fuel circulates throughout the engine.

Caring for the Batteries

If your boat is small enough, simply disconnect the batteries and bring them home, add distilled water and charge them occasionally. For larger boats, disconnect the batteries, add distilled water and then periodically reconnect and charge them using shore power.

By following the directions to winterizing your boat’s engine, you are ensuring the best possible performance from your boat’s propulsion system. Next, winterize the hull and interior of the boat so when spring arrives, you can be confident that the steps you took in the fall will mean less hassle before getting out on the water again.

Sources: Mad Mariner | Boating World magazine


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