Semiahmoo Marina fuel dock

So Semiahmoo Marina just lowered their fuel prices, and most boaters know that topping off fuel tanks to avoid excessive moisture in tanks is a smart strategy. With winter weather comes other maritime considerations as well.

Whether we own sailboats or powerboats, we need to think about winterization. Here in the Pacific Northwest we might think that our winters are mild, but certainly those of us that have spent previous winters here know that the cold coming down from the Frazier Valley can be brutal, not only to ourselves but our boats as well. So hopefully these tips will keep your boat from unnecessary winter damage.

The objective of winterization is to prevent ice damage to your hull materials, engine, water lines and fuel lines. Freezing ice can cause parts of the boat to expand and crack, and the cold can also cause many changes in the boat’s construction materials. Water damage occurs from the continual expansion and contraction that occurs during our typical winter season. We’ll outline all the winterization steps below.

What winterization involves

The most basic element of winterization is draining the boat of any water that may have found its way aboard, replacing it with antifreeze. Water, as many of us know, expands when it freezes, unlike all many other liquids, which can contract. The expansion rate varies somewhat with whatever additional substances are present. For fresh water, it is about nine percent, and the force with which it pushes outward can amount to thousands of pounds per square inch. (For comparison, the atmospheric pressure on your body is about fifteen psi). Such pressure can be extremely dangerous to the parts of your boat — within the course of a single night, it can damage the fiberglass, destroy the refrigeration system, split the hoses or produce cracks in the engine block. Engine cracks have been the cause of 75 percent of all boat insurance claims, according to a ten-year study by BoatUS Marine Insurance.

In most cases, when you fail to winterize your boat, the consequences will not begin to manifest themselves until the springtime.  After the spring thaw and notice that the engine block has a crack in its side, and brown froth is spewing emanating from it, it’s too late. In too many cases, the engine needs to be replaced completely, and even if it does not, fixing the problem takes a great deal of work.


Here is a list of the winterization tasks according to BoatUS.

In the engine room

The engine

  • The oil and the filter should both be changed, as should the fuel filters or separators.
  • The tanks should be filled, with stabilizer added to the gasoline.
  • The level of coolant in the freshwater-cooling system should be checked and increased if necessary.
  • Antifreeze should be run through the raw water-cooling system and used to fill the water strainers.
  • On the gasoline engine fog the cylinders.
  • The battery electrolyte level should be at its maximum, and the marine charger should have batteries connected.

The generator

The checklist for the generator is the same as that for the engine: The oil, filter, fuel filters and separators should all be changed, additional coolant put into the freshwater cooling system if necessary.


On the outboards

  • The installed fuel tanks, like the engine, should be filled, and stabilizer added.
  • The gear case should be drained, and fresh lubricant added.
  • The flush engine should be flushed
  • The unit should be stored in the lowest possible position.
  • Anodes should be inspected and replaced if necessary.
  • The fuel in the portable tanks should be stored at home during the winter.

Now once you’ve gotten these things taken care of, pour yourself a cup of hot chocolate and relax knowing you’ll be ready to go come next boating season!


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