Winterizing protects a boat from the two things that hurt it over a long lay-up: water freezing inside the systems, and fuel going stale. Discover Boating calls freeze damage the biggest potential problem, with mould and corrosion close behind.
Fuel: full or empty
Soundings asked a fuel specialist, Tom Zarrella of USA Fuel Service, and his answer was "fill 'er up". Fuel industry experts now recommend storing the tank at 90 percent of capacity: a smaller volume of air means less condensation in fuel that absorbs water, and the rest leaves room for expansion. Stabilizer, he says, can extend the fuel's shelf life to 18 to 24 months.
Discover Boating's first and most important step is the stabilizer: dose the tank, then run the engine so treated fuel reaches the whole system. With ethanol-blended fuel, skipping it risks phase separation and water-saturated fuel in spring. Change the fuel filters and water separators at the same time.
The engine
| Engine | Discover Boating's steps |
|---|---|
| Inboard | Change the oil. Run antifreeze through the raw water system with the engine at operating temperature, so the thermostat is open, until it comes out of the exhaust. Fog the engine. |
| Sterndrive | Change the oil. Remove the block plugs to drain the water and sediment. Bring it to temperature before fogging. |
| Outboard | Change the lower unit oil and check it for water. Fog it. Leave it tilted down all the way. |
For an inboard afloat, Discover Boating's method is to close the intake seacock, put the hose in a bucket of environmentally safe antifreeze, and run the engine until antifreeze shows at the exhaust. Draining through the petcocks and plugs is the alternative.
Outboards need less: where the engine can be run every few weeks, extra steps usually aren't necessary, because long periods without use do more harm than low temperatures.
Water systems and heads
- Drain every freshwater system, including sinks, tanks and heads, then run non-toxic antifreeze through.
- Open the taps from the farthest to the nearest until each runs with antifreeze, hot and cold, so the water heater gets it too, or drain the heater separately.
- Pump antifreeze through the heads. Empty and remove a portable toilet.
- Run raw water washdown and livewell pumps dry, and give them antifreeze if they still gurgle.
Batteries
Out of the water, charge the batteries fully and turn the switches off. A boat left afloat needs clean, fully charged batteries, and a charging system that works.
The checklist and the survey
Our end of season decommissioning checklist turns this into a list to tick, boat by boat, and the pre-season commissioning checklist undoes it in spring. With Axsail the person laying up the boat says what they've done and found, and the list fills in with photos.