Winch Covers for Winter: Why and When to Fit Them

A winch cover protects the most expensive moving part on your deck from the three things that destroy it slowly and invisibly: ultraviolet light, salt crystals, and the moisture that condenses inside the drum every night. Fitting covers at the end of the season, after a proper rinse and a dry day, is one of the cheapest maintenance decisions an owner can make, because a winch that spends five months sealed against grit and damp comes out of layup in the same condition it went in.

Most owners think of winch covers as a summer accessory, something you slip on when the boat sits in the marina for a fortnight in August. That is a legitimate use, but it is not where the covers earn their keep. The real damage happens over the winter, during the long months when nobody is looking, when the boat sits still under a grey sky and the temperature swings twenty degrees between afternoon and dawn. This article explains what actually attacks a winch during layup, when covers should go on, how to prepare the winch first, and how to choose a cover that does the job rather than one that makes things worse.

What a winch cover actually protects against

It helps to be precise about the enemy, because the answer changes how you use the cover. A winch is an assembly of aluminium or chromed bronze, stainless steel pawls and springs, plastic bearing cages, and a film of grease holding it all together. Each of those materials fails in a different way, and the cover addresses three distinct attack routes rather than one generic idea of "weather".

Ultraviolet light and heat

UV is the slow one. It does not touch the metal, but it degrades every polymer in and around the winch: the plastic bearing cages inside the drum, the composite washers on some models, and any exposed line left riding on the drum. Over several seasons UV makes those parts chalky and brittle, and a brittle bearing cage is what turns a smooth winch into a gritty one. Heat compounds it. A dark winch drum in direct sun can sit well above ambient temperature for hours, and warm grease migrates. It runs down out of the bearing races and pools where it does no good, leaving the upper bearings dry by the time you next use them.

Salt and airborne grit

Salt is the fast one, and it is the reason a boat kept ashore near the water still suffers. Salt crystals are hygroscopic: they pull water out of humid air and hold it against the metal as a concentrated brine. That brine sits in the gap between the drum and the base, exactly where you cannot see it, and it drives crevice corrosion on stainless components and pitting on anodised aluminium. Airborne grit does something more mechanical. Dust, yard sand, and the fine grinding debris that drifts across a boatyard in winter settle on the greased surfaces and turn a lubricant into a mild abrasive paste.

Moisture, condensation and mould

The third route is the one owners underestimate. An uncovered winch on a boat under a tarpaulin goes through a condensation cycle every single night. The metal cools faster than the air around it, water condenses on the drum and runs down inside, and in the morning it either evaporates or does not, depending on how well the boat is ventilated. Repeat that for a hundred and fifty nights and you have a bearing race that has been wet more often than dry. Where organic material is present, from old grease, salt residue, or a dirty cover, that damp environment grows mould, which is unsightly on the outside and genuinely corrosive underneath.

Why winter is the critical season

A winch in use during the season is, paradoxically, quite well looked after. It gets rinsed by rain and spray, it turns regularly so the grease redistributes, and any problem announces itself immediately because you feel it in the handle. A winch in layup gets none of that feedback. It sits motionless for months, and whatever state it was in on the day you left it is the state it will deteriorate from.

The grease behaviour matters here. Marine winch grease is formulated to stay put at working temperatures, but in cold weather it stiffens and its film thins where it has already been displaced. If the winch went into layup with salt-contaminated grease, the salt stays in contact with the bearings for the entire winter rather than being flushed and replaced by normal use. This is why a winch that felt fine in October can feel notchy in April despite nobody touching it.

There is also the practical matter of the boat cover itself. Many owners fit a full tarpaulin or shrink-wrap and assume the deck is protected. It is protected from direct rain, but a covered boat is often a more humid boat, not a drier one, because the tarpaulin traps evaporating moisture from the bilge and the interior. Under those conditions bare metal on deck sees more condensation, not less. A winch cover works with the boat cover rather than being made redundant by it.

When to fit winch covers

During the season

Through the sailing months, covers are worth fitting whenever the boat will sit unused for more than a week or two, particularly in high summer when UV load is at its peak and the boat is in a berth all day. The discipline to build here is simple: covers go on when you leave, and they come off before you start preparing to sail. Owners who leave covers on while working the boat inevitably end up with a cover trapped under a loaded sheet, which is how covers get torn.

At the end of the season

The correct moment to fit covers for winter is not the day you stop sailing. It is the first dry day after you have rinsed the deck, and that distinction matters more than anything else in this article. A cover fitted over a wet or salty winch does not protect it; it seals the problem in. You are creating a small, dark, humid chamber around a piece of salt-contaminated metal and leaving it there until spring. Fitting covers correctly means accepting a short delay: rinse thoroughly, let the boat dry properly for a day in moving air, then cover.

If your end-of-season layup schedule does not allow a dry day, and in some autumns it genuinely does not, the honest choice is to leave the winches uncovered rather than cover them wet. An exposed winch that dries out is in better shape by March than a sealed damp one. You can always return with the covers later.

Preparing the winch before covering it

Rinse and dry

Start with a generous freshwater rinse, not a quick splash. The aim is to dissolve and carry away salt, which means volume and time rather than pressure. Avoid a high-pressure lance aimed at the drum gap: it drives water and salt further into the bearings rather than flushing them out, and on some winches it will push grease straight out of the races. A hose at normal pressure, run over and around the winch for a good half minute each, does more good. Then let it dry in air and, if possible, in a little sunshine.

A quick service check

Layup is the natural moment to assess whether the winch needs a full service before it is put away, because a winch stripped, cleaned and regreased in October is ready to sail in April rather than being a job standing between you and the first weekend. Spin the drum by hand and listen. A smooth, even whirr is fine. A gritty rasp, a click that changes character as you rotate, or a drum that feels tight in one part of its travel all indicate that the bearings need attention. Lift the drum if your model allows it without tools and look at the grease: it should be soft and pale, not dark, dry, or streaked with grey metallic residue.

What not to do

Do not spray the winch with a general-purpose water-displacing lubricant as a substitute for service. Those products are thin solvents by design, and their effect on a bearing is to dilute and wash out the heavy grease that is meant to be there, leaving a light film that will not survive a season. Do not leave a rope tail wrapped on the drum under the cover either. It holds moisture directly against the metal and it will leave a permanent mark on the anodising.

Choosing a winch cover

Fit and sizing

A cover has to match the winch, and the relevant measurements are the drum diameter at its widest point and the overall height from the deck to the top of the winch. Covers that are too small do not seat down onto the base and leave the lower part of the drum exposed, which is precisely the area where water collects. Covers that are too large flap. Flapping is not a cosmetic problem: a loose cover in a winter gale abrades the anodising it is supposed to protect, and it works its fastening loose until it disappears across the yard. Measure before buying, and if your boat has self-tailing winches remember the tailing arm adds to the diameter.

Material and breathability

This is where the real difference lies between covers that help and covers that hurt. A completely waterproof, non-breathable cover keeps rain out but also keeps condensation in, and the result over a winter is a humid pocket that grows mould. What you want is a fabric that sheds liquid water while letting vapour escape, so that whatever moisture does form can leave. Acrylic canvas and coated breathable synthetics both do this. Treated fabrics with an anti-mould finish add a further margin in exactly the conditions that a winter layup produces, which is the reason that finish exists.

Fastening

The cover has to stay on for five months without being tended. Drawstrings with a cord lock are the common solution and they work well provided the cord is synthetic and the lock actually grips. Elasticated hems are convenient but they relax over time and are the usual culprit when covers go missing. Whatever the system, it needs to cinch below the widest part of the drum so that the cover cannot be lifted off by wind getting underneath.

Comparison at a glance

Cover type	Water resistance	Breathability	Winter suitability
Coated PVC, non-breathable	High	None	Poor: traps condensation for months
Untreated cotton canvas	Low	High	Poor: absorbs water, grows mould itself
Acrylic canvas	Good	Good	Good: the traditional compromise
Breathable synthetic with anti-mould finish	Good	Good	Best: designed for long damp layup

Fitting and removing covers

Fitting is straightforward but worth doing deliberately. Seat the cover fully down onto the deck so the hem lies flat rather than bridging over the winch base, then draw the cord until it is snug and lock it. Snug, not strangled: over-tightening a drawstring distorts the fabric and creates permanent creases that channel water inwards. Give each cover a firm tug once fitted; if it lifts, it is not tight enough.

When you take covers off in spring, do not simply stuff them into a locker. Shake them out, check the fabric for mould spotting and the cord for chafe, wash them if the manufacturer allows it, and dry them completely before storage. A cover put away damp in April is a cover full of mould in June, and it will transfer that straight onto the winch the following winter. Store them somewhere dry and label them if your boat has winches of different sizes, because working out which cover fits which winch on a cold October afternoon is a tedious way to spend twenty minutes.

Common mistakes

The first and most damaging mistake is covering a wet or salty winch, which has already been covered above but bears repeating because it is by far the most common. The second is treating the cover as a substitute for maintenance. A cover slows deterioration; it does not service a winch, and a neglected winch under a good cover is still a neglected winch. The third is leaving covers on in the water during the season without checking them, which allows a small amount of trapped damp to sit unnoticed for weeks. The fourth is using the wrong size and accepting the flapping, which quietly wears away the finish it was bought to preserve.

A fifth, less obvious mistake is forgetting the rest of the deck hardware while carefully protecting the winches. Blocks, cars, clutches and any exposed low-friction hardware benefit from the same rinse-and-dry discipline, even where a dedicated cover is not available. If you are already on deck with a hose in October, spending an extra ten minutes on the rest of the fittings costs almost nothing.

Frequently asked questions

Do I need winch covers if the boat is shrink-wrapped for winter?

Yes, and arguably more than if it were not. Shrink-wrap and tarpaulins keep rain off but they also restrict airflow, and a poorly ventilated covered boat is a humid one. The condensation cycle continues underneath, so the winches still spend their nights wet. Covers give the metal a second line of defence, and a breathable cover will not trap that moisture against the drum.

Can I use winch covers on a boat kept in the water all winter?

Yes, and it is a good idea. A boat afloat is in a more humid microclimate than one ashore, and it also sees more salt spray from wind across the harbour. The one caution is to check the covers occasionally through the winter rather than fitting them in November and forgetting them, because a cover that has worked loose in a gale is doing nothing at all.

Should I service the winches before or after the winter?

Before, if you can. Servicing in autumn means the bearings spend the winter in clean grease rather than in salt-laden old grease, and it means the boat is ready to sail on the first good weekend of spring rather than waiting for a maintenance day. The counter-argument is that grease can stiffen over a long cold layup, but that is a minor and reversible inconvenience compared with five months of salt sitting in a bearing race.

What size winch cover do I need?

Measure the widest diameter of the drum, including the self-tailing arm if fitted, and the height from the deck to the top of the winch. Match those figures to the manufacturer's sizing rather than working from your winch's model number alone, because the same nominal size from different makers varies. If you fall between two sizes, the larger one that can be cinched down tightly is usually the safer choice.

How long do winch covers last?

A good acrylic or treated synthetic cover, fitted and stored properly, will give several seasons of service. What kills covers early is being left on all year round in strong sun, being stored damp, and being fitted so loosely that they flap. Inspect the hem and the drawstring channel each spring, since those are where wear appears first.

The short version

Winch covers are not a summer luxury, they are winter insurance. The winch is protected against UV, salt and airborne grit, and against the nightly condensation cycle that runs unnoticed under a boat cover for months. Fit them at the end of the season, but only after a thorough freshwater rinse and a full dry day, because a cover over a wet winch does more harm than no cover at all. Choose a cover that fits the drum properly, breathes rather than sealing, and fastens tightly enough to survive a winter gale. Then take them off in spring, dry them, and put them away clean for next time.