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Boat Winterizing Checklist

Everything on the boat except the motor — which has its own list — in the boat builders’ own words: the water out, the battery, the trailer, the cover, and the spring list on the other tab.

Which end of the season?
The boat
Where it spends the winter

Pontoon · stored outdoors

14 jobs for the boatWater out of everything first, the motor on its own list, the battery off, the trailer checked, and a cover that sheds snow. Under each job are the words of the builder who published it: Barletta, Avalon, Bennington and NITRO.

The owner’s manual that came with your boat outranks every line here, and a job you are not sure of is a dealer’s job — most dealers winterize, store and shrink-wrap.

Every builder’s guide was read 2026-09-26. Your boat’s owner’s manual outranks every line here.

The winter list

1 · Out, cleaned and emptied

2 · Every drop of water out

3 · The motor

4 · The battery

5 · The trailer

  • NITRO — the original words

    NITRO: “Be sure to pay extra attention to the hubs, wheel bearings and seals. It’s also a good practice to check your lights, and inspect brakes and tires for wear.” NITRO Boats — Winterize Your Fishing Boat & Prep for Cold Weather · read 2026-09-26

  • Barletta — the original words

    Barletta: “Lastly, make sure the boat trailer isn’t going to roll anywhere on its own by adding a heavy stone or wood or cinder block behind or in front of the wheels.” Barletta Pontoon Boats — How to Winterize a Pontoon Boat (6 Easy Steps) · read 2026-09-26

6 · Covered, and closed to critters

  • Barletta — the original words

    Barletta: “If you plan on storing the boat outdoors, it’s strongly suggested that you have it shrink wrapped.” Barletta Pontoon Boats — How to Winterize a Pontoon Boat (6 Easy Steps) · read 2026-09-26

    Avalon: “Shrink Wrapping provides the best protection against moisture and you don’t have to worry about the cover sagging or blowing off.” Avalon Pontoon Boats — How to Winterize a Pontoon Boat · read 2026-09-26

    NITRO: “If you have to store your boat outside, it’s strongly recommended to wrap it to keep it dry and reduce the chances of mice, squirrels or other critters making a cozy home over the winter months.” NITRO Boats — Winterize Your Fishing Boat & Prep for Cold Weather · read 2026-09-26

  • Bennington — the original words

    Bennington: “If stored outside where this is snowfall, ensure the boat cover doesn’t allow snow to build up on the cover, which could potentially cause damage to windshields.” Bennington — Boat Winterization Guide: Protect Your Boat · read 2026-09-26

  • Bennington — the original words

    Bennington: “A boat can be an appealing place for critters during cold winter months, and a plastic or canvas barrier only offers temporary protection from their sharp, gnawing teeth.” Bennington — Boat Winterization Guide: Protect Your Boat · read 2026-09-26

Quick answer: winterizing a boat is two lists. The motor has its own, in a strict order — that is the Outboard Winterizing Checklist. The rest of the boat is this one: haul it out, clean it while the growth is still wet, take everything off that comes off, dry the inside before you close it up, empty every livewell and the bilge and pull the drain plug, charge and disconnect the battery, go over the trailer’s hubs and bearings, and cover it — shrink-wrapped if it winters outdoors. Every step here is a boat builder’s own words: NITRO, Bennington, Barletta and Avalon.

What freezes, and why it matters

Almost everything that goes wrong over a boat’s winter is water. Water left in a livewell pump, a washdown line or the bilge freezes, expands and splits whatever it is in; water left in the upholstery and carpet under a cover turns into mildew. That is why the list starts with the boat empty and dry, and why the drain plug comes out and stays out all winter. NITRO puts it plainly: water “in any part of your boat’s system — the lower unit, livewell or bilge area — could cause major problems”.

What changes with where it winters

The jobs that depend on where the boat spends the winter
JobOutdoorsIndoorsIn the water
Drain plug outYesYesNo
Battery off, kept chargedYesYesNo
Battery aboard for the bilge pumpNoNoYes
Trailer hubs, bearings, lights, tiresYesYesNo
Shrink-wrap or a supported coverYesNoNo
Brush off heavy snowYesNoNo
Mooring cover, tarp over itNoYesNo

Leaving the boat in the water is the exception, and the builders treat it as one: Bennington’s own advice is to pull it out and store it on land. If it does stay in, the battery stays aboard, connected and charged, because it is what runs the bilge pump.

Where the builders disagree

On the battery. Avalon says to store it “someplace cool”, fully charged and topped up through the winter — the same as Mercury’s advice for an outboard’s battery. Barletta’s writer would keep it in a heated space on a maintainer. Both agree on the part that matters: a battery that goes flat can freeze. The checklist shows both, so you can pick the one your garage allows.

Pontoons and fishing boats

A pontoon’s extra jobs are its tubes — scrubbed the day they come out, while the growth is still soft — its furniture, which grows mildew if it is closed up damp, and the steering, which has grease fittings. A fishing boat’s extra job is water: livewells, baitwells and the bilge, every one emptied. Both get the same critter warning from Bennington: a cover is a “temporary protection” against a mouse, so the real defence is nothing aboard worth moving in for.

If you are still building the pontoon, that is How to Make a Pontoon Boat; the motor’s own list is linked in the checklist, and its long version is How to Winterize an Outboard Motor, in the Order That Matters.

FAQ

How do you winterize a boat?
In two parts. The motor has its own ordered list — fuel stabiliser run through, oil, fogging, gear lube, left vertical. The rest of the boat: clean it, take off everything removable, dry the interior, empty the livewells and bilge and pull the drain plug, charge and disconnect the battery, check the trailer, and cover it — shrink-wrap if it winters outdoors.
Should I leave the drain plug in or out over winter?
Out, on land. NITRO’s own guide says not to forget to pull the drain plug when storing the boat at home. With it out, any rain or melt that gets in can run out rather than sit in the bilge. Put it somewhere you will see it in spring, and put it back before the boat goes near the water.
Should I take the battery out of my boat for winter?
On land, yes: charge it fully, disconnect it and keep it topped up — a low battery can freeze. Avalon says store it somewhere cool; Barletta’s writer prefers a heated space on a maintainer. If the boat stays in the water, the battery stays aboard and charged so the bilge pump can run.
Is shrink-wrap better than a boat cover?
For outdoor storage the builders lean that way: Barletta strongly suggests shrink-wrap outdoors, and Avalon says it gives the best protection against moisture without a cover sagging or blowing off. Indoors, the mooring cover you use at the dock is enough, with a tarp over it if birds get into the building.
Can I leave my pontoon in the water over winter?
You can, but Bennington recommends pulling it out and storing it on land. If it stays in, keep the battery aboard and charged so the bilge pump works, and keep it covered.
What do I do in spring?
Take the cover off and look at what the winter did: under the tubes for dents or leaks, the hoses and fuel lines for cracks, the propeller, the vinyl and canvas. Put the drain plug back in, the battery aboard and the electronics back on, run through the motor’s own spring list, and check the safety kit — extinguisher dates, lights, horn, flares and a life jacket for everybody.