When and where to store
Book winter storage early: indoor space fills first. Indoor or heated storage is the most protective; covered storage keeps snow off; outdoor storage needs a well-supported cover or shrink-wrap.
Engine and fuel
- Fill the tank (leaving expansion room) and add fuel stabilizer; run the engine so treated fuel reaches it.
- Change the engine oil and filter; change gear lube in the lower unit.
- Drain the cooling system or run antifreeze through it, as the manual says for your engine type.
- Fog the cylinders if the manufacturer recommends it.
- Grease fittings and check the anodes.
Water systems
- Drain fresh-water tanks, water heater and lines, then add non-toxic potable antifreeze.
- Pump out and treat the head and holding tank.
- Leave the drain plug out (and keep it where you will find it in spring).
Battery and interior
- Charge the battery and remove it or keep it on a maintainer.
- Take electronics, cushions and life jackets home.
- Clean out food; put moisture absorbers in lockers.
Cover and checks
- Breathable, fitted cover or professional shrink-wrap with vents, supported so water and snow don't pool.
- Photos of the boat and trailer with the date.
- A visit after storms.
Printable winterization checklist for your engine type: open the tool.
Frequently asked questions
Do I need to winterize if the boat is stored indoors?
If the building isn't heated, yes. Even in heated storage, fuel stabilizer and engine service are standard practice; follow your engine manual.
Can a marina winterize my boat?
Many facilities offer winterization and shrink-wrap; listings show it when there is evidence in the name, website or reviews.
Sources: BoatUS winterizing resources (BoatUS.com/Winterization); CubeSmart boat storage guide; Discover Boating; your engine manufacturer's owner's manual. Guide reviewed on 27 Oct 2026 by the Nautsy team. Spotted an error? Tell us.