This is the short version: a checklist you can work through in order, from booking a space to handing over the keys. It pulls from the BoatUS winterizing guide, Mercury and Yamaha, and from the rules that winter storage yards post for drop-off day. For the longer explanation of each engine type, shrink wrap and jet skis, see our boat winterization and storage guide. Your engine's owner's manual comes first, and many owners have a dealer do the engine work. All sources were checked on November 3, 2026.
Why it matters
BoatUS says fresh water expands by about 9% when it freezes, enough to crack an engine block, split hoses or damage fiberglass overnight. Its review of ten years of GEICO | BoatU.S. freeze claims found more than three-quarters involved cracked engine blocks or exhaust manifolds from water left in the engine or cooling system. BoatUS says the checklist in its guide covers the items that would have prevented more than 95% of those claims, and that winterizing most boats takes from an hour to a day. It also says boats stored ashore need to be winterized earlier than boats in the water, because air temperatures drop sooner. BoatUS: The Boater's Guide to Winterizing (PDF)
1. Before you book: read the yard's rules
Storage yards set their own drop-off rules, and some differ from what engine makers recommend. Read them before you start, because they change what you do with fuel and batteries. Here's what four operators post:
- Jerome County Fairgrounds (Idaho): fuel as empty or as low as possible, and all batteries disconnected, before you bring the item in. You back in and park it yourself. Jerome County Fairgrounds: Winter Storage
- Minnesota State Fair: portable propane and portable fuel tanks must be removed or emptied (containers of 2 1/2 lbs and under excepted, up to 24). The buildings are unheated, so items must be winterized. Minnesota State Fair: Storage General Information
- Dakota County Fairgrounds (Minnesota): no propane tanks unless they're built in (as on an RV), staff park every unit, and motorized units must be handed over with a full set of keys. Units can't be stored on blocks or with tires removed. Dakota County Agricultural Society: Off-Season Storage
- Fairwinds Marina (Warwick, Rhode Island): proof and a certificate of insurance are required, every hauled boat is power washed, and shrink wrap can't go in the marina's dumpster. Fairwinds Marina: 2026-2027 Winter Storage on Land (PDF)
Some marinas do the winterizing for you and require it. Geist Marina and Morse Marina near Indianapolis both say boats stored with them must add a winterization option and a spring start and launch fee, and that their inside storage barn isn't heated, so the engine still needs winterizing. Geist Marina: Boat Storage · Morse Marina: Boat Storage
If a yard's rule conflicts with your engine maker's advice (for example, on how full to leave the tank), ask the yard before drop-off. Its rule decides whether it will take the boat.
2. Fuel
- [ ] Treat the fuel with a marine stabilizer. Mercury says untreated fuel oxidizes and forms gum in the fuel system, and its dealers see most problems from stale fuel. If the fuel is more than a month old and you can't use it up, Mercury suggests having it pumped out and replaced. Mercury: How to Winterize Your Outboard
- [ ] Run the engine about 10 minutes (in the water or on a hose flusher, per your manual) so the treated fuel reaches the whole system, then replace the fuel filter. Mercury
- [ ] Decide the fuel level, yard rules permitting. Mercury says older boats with vented tanks should be filled to about 95% to limit condensation, while newer tanks that can't vent freely don't need to be filled. Yamaha says to store with the tank 7/8 full and never to plug or cap the tank vent. Mercury · Yamaha Outboards: Extended Storage
- [ ] Portable tanks: BoatUS suggests emptying portable four-stroke tanks into your car and taking them home, which also satisfies yards that ban portable fuel tanks. BoatUS (PDF)
3. Engine and drive
- [ ] Change the oil and filter (four-strokes, inboards and sterndrives), and the fuel filter or water separator. Yamaha notes water left in a fuel filter canister can freeze. Yamaha Outboards · BoatUS (PDF)
- [ ] Fog the engine. Mercury says to spray fogging oil into each cylinder on four-strokes and conventional two-strokes, but to use one ounce of DFI outboard oil per cylinder on direct-injected two-strokes such as OptiMax. BoatUS notes some newer outboards have an automatic winterizing feature. Mercury · BoatUS (PDF)
- [ ] Drain the gearcase and refill with fresh lube, and inspect or replace the anodes. BoatUS (PDF)
- [ ] Grease the fittings. Yamaha says greasing the zerks with the grease your manual specifies helps force out water. Yamaha Outboards
- [ ] Inboards, sterndrives and generators: run antifreeze through the raw-water cooling system, make sure the water strainers are filled with antifreeze, and check the coolant in any freshwater-cooled system. BoatUS (PDF)
- [ ] Leave the outboard or drive tilted down. BoatUS says to store outboards in their lowest position. Yamaha says an outboard stored outside should be trimmed full-in, or have a sealed plastic bag over the dry lower unit, so moisture can't collect and freeze. BoatUS (PDF) · Yamaha Outboards
4. Water aboard
From the BoatUS checklist:
- [ ] Pump out the holding tank and add antifreeze to the head.
- [ ] Drain the water heater and bypass it.
- [ ] Drain the freshwater system and run antifreeze through it.
- [ ] Run antifreeze through the live well and washdown pump, per your owner's manual.
- [ ] Flush and fill air conditioning and refrigeration systems with antifreeze, if fitted.
- [ ] Drain the shower sump and anywhere else water pools.
- [ ] Clean and dry the bilge, and check that the bilge pump and switch work.
- [ ] Pull the drain plugs. BoatUS says they must be out for the winter to prevent freeze damage.
BoatUS: The Boater's Guide to Winterizing (PDF)
5. Batteries
- [ ] Charge fully before storage. Yamaha suggests a load test, a monthly charge check, and bringing batteries indoors to a cool, dry place if the boat is stored outside. Yamaha Outboards
- [ ] Small boats: BoatUS says that on small boats not left in the water you may want to take the batteries home and put them on a charger. If you keep them aboard, it says to keep them on a marine charger with a float setting, or unplugged but fully charged at least once a month. It warns that a battery left on an automotive trickle charger for long periods can boil off its electrolyte and, at the extreme, explode. BoatUS (PDF)
- [ ] Check the yard's battery rule. Jerome County wants all batteries disconnected; Dakota County says batteries may not be removed from motorized vehicles such as cars and motor homes. Ask which applies to your boat.
6. Inside the boat
From the BoatUS checklist: remove food, open lockers to air, take home cushions (or stand them on their sides) and portable electronics, close the propane valves and take portable canisters home, secure the ports and hatches, and turn off every breaker except the bilge pump and smoke or vapor alarms. Yamaha adds: wash the boat and outboard and make sure the boat is bone dry before you close it up. BoatUS (PDF) · Yamaha Outboards
7. Support, trailer and cover
- [ ] On a trailer: BoatUS says ideally take it to a gated, secure storage facility. If you can't, keep it away from overhanging branches and from buildings with sloped roofs, where sliding ice and snow can damage the boat.
- [ ] On jack stands: BoatUS says to place stands as far out as practical, at least three per side for boats over 26 feet, with extra support at overhangs. Sight along the hull to make sure the stands aren't pushing it in, check again after about two weeks, and keep the boat level so water doesn't pool.
- [ ] Cover: a framed, vented cover is best. Never tie the cover to jack stands or blocks; a strong wind can pull them out. Shrink wrap needs vents along its entire length, and BoatUS says to leave shrink wrapping to professionals because a moment of inattention can ignite the wrap. Some yards, such as the St. Clair Shores city lot in Michigan, make the owner responsible for wrapping, so book a pro early. St. Clair Shores: Winter Trailer/Boat/Camper Storage
- [ ] Steering: tie off the tiller or wheel.
BoatUS: The Boater's Guide to Winterizing (PDF)
8. Drop-off day
- [ ] Insurance certificate, if the yard asks (Fairwinds requires one). See RV and boat insurance while in storage.
- [ ] Keys, if the yard parks the boat itself (Dakota County).
- [ ] Your length measured the way the yard measures it. Champlain Valley Expo measures "ball hitch to propeller." Champlain Valley Expo: Winter Storage
- [ ] The pickup date in your calendar. Jerome County pickup runs March 15 to 26, 2027, and items not removed by April 1 are towed at the owner's expense. Jerome County Fairgrounds
For what seasonal storage costs, see how much RV winter storage costs; most of the fairgrounds there take boats too.
Winter boat storage near you
City pages list storage, ramps and marinas near each city, using what each business states on its own site:
- Indianapolis, Indiana (Geist and Morse marinas)
- Warwick, Rhode Island (Fairwinds Marina)
- Detroit, Michigan (St. Clair Shores lot)
- Minneapolis, Minnesota
- Burlington, Vermont
- Twin Falls, Idaho
- Idaho Falls, Idaho
- Casper, Wyoming
- Portland, Maine
Related guides
- Boat winterization and storage: engines, fuel, shrink wrap
- How much RV winter storage costs
- Covered vs indoor vs outdoor RV and boat storage
- Jet ski and PWC storage
FAQ
Should I fill the boat's fuel tank or empty it before storage?
Engine makers and yards disagree. Mercury says older vented tanks should be filled to about 95% with stabilized fuel, and Yamaha says 7/8 full, but Jerome County Fairgrounds wants fuel as low as possible before drop-off. Follow the yard's rule if you're storing there, and ask it if you're unsure.
Do I need to winterize a boat going into indoor storage?
Yes, unless the building is heated. The Minnesota State Fair and Dakota County say their storage buildings are unheated and units must be winterized, and Geist Marina says its inside storage barn isn't heated.
Should I take the battery out of my boat for winter?
BoatUS says that on small boats not left in the water you may want to take the batteries home and keep them charged, and it warns against leaving them on an automotive trickle charger for long periods. Yamaha says to bring them indoors if the boat is stored outside. Some yards, like Jerome County, ask for batteries to be disconnected.
How long does winterizing a boat take?
BoatUS says most boats take from an hour to a day.