If you use your boat year-round, you probably have a small heater on board to protect your systems between frequent sails. However, if you leave your boat for any extended period of time, there are steps you should take to insure boat systems’ survival through the winter.
We are in denial about summer being over. Today we needed protective gear to keep the liquid falling from the sky off of us and to deal with the somewhat lower temperature. This, for some of you, will signal putting your boat to bed for the “not summer season.” Maybe if we do not say the “W” word, it won’t happen! But, to bite the bullet, let’s talk about winterizing. Things are going to get cold and wet. There are many concerns, but the first thing to think about is freezing. Depending on your boat’s particular configuration, the idea is to not leave any standing water in any of the systems which could freeze, expand and break something.
Raw water system– The freezing point of seawater is about 28.4°F (-2°C), depending on its salinity, and 32°F (0°C) is the freezing point for ordinary water. Water must be drained from the whole system including the thru hull, the raw water strainer, raw water pumps, any manifolds, valves, engine parts, exhaust water lifts, and mufflers. If you have an outboard motor, flush and drain it. Impeller pumps are usually drained by removing the front plate. (Figure 1) The water can be removed from the strainer by a drain or by unscrewing and emptying it. Engine exhaust manifolds and water jackets should have a drain. (Figure 2) The system should be left empty, or full of the appropriate antifreeze.
Fresh water system: Empty fresh water tanks and pump non-toxic antifreeze through the system. Open all showers, faucets and let them run until you have antifreeze coming out. Check any sumps to make sure they are empty. We only know of one bio-friendly glycerin coolant. All the others are glycol based ethylene glycol or propylene glycol. Ethylene glycol is typically used in engines and is highly toxic. Propylene glycol is considerably less toxic but may be labeled “non-toxic antifreeze” and can have a negative environmental impact when you flush out your system in the spring.
Fuel: Gasoline and Diesel are both treated differently.
It is important to know whether the gas in your tank has ethanol in it. If the answer is “Yes,” you should consider using or transferring the gas somewhere else. The reason for this is that when water comes in contact with ethanol, as it has a good chance of doing during the winter, it is absorbed until a saturation point is reached. Then, the water, ethanol, and the gasoline will phase separate, forming two or three distinct layers in the tank. This is irreversible. With regular gasoline, the best advice is to use a gasoline stabilizer and keep your tanks 1/4 to 1/2 full so that in spring you can put new fuel in the tank to bring the octane level back up. Buy it at a fuel dock that gets frequent deliveries and always ask if their gas has ethanol in it. For diesel, fill the tank and mix in an additive to kill fungus.
In both cases, gas and diesel, install a water separator in the fuel line before the main filter. It is recommended that you change your oil now so the acid that forms in used oil does not have a chance to eat at your engine during the long winter nights.
Covers: Varnish and bright work can take a real beating in the winter so covering handrails and other treated wood can save you work in the spring. In some cases, such as with tillers, you may be able to remove them to protect the wood. This will also give you a chance to varnish them to prepare for your next sailing season. If you have doubts about the condition of the varnish on other parts of the boat, it is probably better to give them a couple of coats when the weather permits.
Another thing to consider about freezing weather is again that pesky standing water. If you have a place on your deck that water can get into in any quantity, it will then expand as it freezes. This is called frost wedging and in nature it can crack and break huge boulders. Avoid having low places in your covers and awnings that will collect water because ice can cut them with its sharp edges.
Mold: To grow, it needs moisture, humidity of around 50%, a lack of ventilation, and organic matter — for example; dirt, dust, clothes, paper, wood, etc. If you want to make it difficult for mold to get a hold in your boat, keep the humidity low, the space well ventilated, and all surfaces clean and disinfected. Do not leave clothes, paper or food lying around. To keep the humidity low you can use one of many electrical or chemical dehumidifiers on the market. (Figure 3)
Holding tanks: Both black and gray water should be pumped out and the tank treated with some product that will deal with the anaerobic sludge that builds up inside of them.
Check these: Zincs, bilge pumps, shaft seals and thru hull fittings should be checked before you leave your boat until spring. Also, make sure there is no oil in your bilge which could be pumped overboard by the automatic bilge pump in your unattended boat. It is also a good idea to use engine fogging oil on outboards or inboard engines after cleaning them off for the winter. (Figure 4)
The above are general guidelines. The best course of action is to use your boat throughout the year. The beauty of the Pacific Northwest is not diminished by a little drop in temperature, and systems on boats often suffer more from disuse rather than wearing out from overuse.
Jack Wilken, has an extensive boat building background. In 1979 he sailed from Seattle in a Yamaha 33, to Martha’s Vineyard / 1983-2004 French Canals to the Mediterranean in a Pretorian 35 & 50’ steel ketch (Galapagos 50). Son Alex, has a degree in Marine Carpentry-Wood Construction. Jack and Alex own Seattle Boat Works, firstname.lastname@example.org