Preparing Your Boat for Winter

October arrives and half the boats at Portishead Quays get covered up and forgotten until April. That’s five months of cold, damp, and darkness doing damage to your boat while you’re not looking. A couple of days spent on winter prep now saves weeks of remedial work in spring.

I’ve seen what happens to boats that get put away dirty. It’s not pretty.

Why Winter Prep Matters

Dirt left on surfaces over winter becomes permanent staining. Salt crystallises into gelcoat. Moisture trapped inside causes mould, mildew, and rot. Damp fabric starts to smell. Metal fittings corrode.

The boat doesn’t stop deteriorating just because you’ve stopped using it. In some ways, winter is harder on a boat than summer. Summer has sunshine and ventilation. Winter has condensation, freezing temperatures, and minimal airflow under covers.

A boat that goes into winter clean and properly prepared comes out of winter needing a fraction of the work. A boat that goes in dirty comes out needing serious attention.

The numbers make the case. A proper winter prep clean costs a few hundred pounds. Fixing the damage caused by skipping it costs a few thousand. New upholstery because of mould? New teak overlay because of black spots that went unchecked? I’ve quoted those jobs. They’re not cheap.

Exterior Prep

Start outside and work in.

Full wash and rinse. Every surface. Hull above the waterline, decks, cockpit, superstructure, rails, stanchions. Remove every trace of salt and dirt. Use a proper marine shampoo, not washing-up liquid (it strips any remaining wax protection).

Inspect while you wash. This is when you spot things. Cracked sealant around windows or deck fittings. Corroded screws. Worn sacrificial anodes. Chafed lines. Note everything. Fix what you can now. Schedule the rest for spring.

Polish and protect. If the gelcoat isn’t ceramic coated, apply a good quality marine wax or sealant. This protects against winter UV (yes, winter sun still damages gelcoat) and stops dirt bonding to the surface. If you’ve got a ceramic coating, a maintenance wash is enough.

Teak care. Clean teak decks thoroughly. Apply teak oil or protector. Don’t leave teak untreated over winter, it’ll go grey and develop black spots.

Canvas and covers. Clean all canvas. Check for tears and failed stitching. Reproofing spray extends the life significantly. If you’re using a winter cover, make sure it’s properly fitted with adequate ventilation. A tight cover with no airflow creates a perfect environment for mould.

Metal fittings. Clean and protect all stainless steel and chrome. A thin film of protective spray on winches, cleats, and fittings prevents surface corrosion. Don’t forget pushpit and pulpit joints.

Honestly, most people underestimate how long exterior prep takes. Budget a full day for a 30-35ft boat if you’re doing it properly. Rushing leads to missed spots that cause problems later.

Interior Prep

The inside is where winter damage hits hardest if you get it wrong.

Deep clean everything. Galley, heads, saloon, cabins. Every surface wiped down. No food residue anywhere. A single crumb behind a cushion becomes a mould colony by February.

Remove soft furnishings if possible. Cushions, pillows, sleeping bags, towels. Take them home. Store them somewhere dry and warm. If you can’t remove them, stand them on edge so air can circulate around them. Never leave cushions flat on bunks over winter.

Clean bilges. Pump out any water. Clean with bilge cleaner. A dirty bilge in a closed-up boat smells terrible by spring and encourages corrosion.

Empty the galley completely. No tinned food, no dried goods, no condiments. Mice and rats don’t care that it’s a boat. They’ll find it. Open all locker doors and drawers to allow airflow.

Clean and leave heads (toilet) completely empty. Pump through with clean water and marine toilet cleaner. Leave the bowl dry. If you have a holding tank, pump it out before winter.

Ventilation. This is the single most important thing for interior winter care. Leave interior ventilation open. Install moisture absorbers (the crystalline type, not electrical dehumidifiers unless you have shore power). Leave internal doors and locker doors open.

Damp check. If you’re visiting the boat during winter, check for damp. A moisture meter costs £20 and can save you thousands by catching problems early.

In the Bristol area, winter humidity is brutal. The combination of rain, proximity to the Channel, and cold temperatures means condensation is almost guaranteed on an unventilated boat. I’ve opened up boats in March that had standing water running down the inside of the hull from condensation alone.

Spring Recommissioning

If you’ve done winter prep properly, spring is straightforward. If you haven’t, spring is expensive.

Exterior:

• Remove winter cover carefully (it’ll be dirty and possibly mouldy itself)
• Wash all surfaces
• Inspect all the items you noted in autumn
• Apply fresh polish or sealant if not ceramic coated
• Check all running rigging and standing rigging
• Check safety equipment (flares, lifejackets, fire extinguisher dates)

Interior:

• Air the boat thoroughly on a dry day before doing anything else
• Reinstall cushions and soft furnishings
• Clean all surfaces again (winter dust accumulates even in a sealed boat)
• Restock the galley
• Check all systems: bilge pump, navigation lights, instruments, gas system
• Run the engine and check cooling, oil, and charging

Below the waterline:

• If you hauled out, inspect the hull
• Apply antifoul
• Check anodes and replace if needed
• Check skin fittings and seacocks
• Relaunch and check for leaks

A well-prepped boat can go from “winter storage” to “ready to sail” in a weekend. A neglected one can take weeks.

We offer full winter prep and spring recommissioning cleaning as part of our yacht cleaning service. We’re based at BS10 5EN, carry £2 million insurance, and have 25 years’ experience.

Call 07985 505061 or email hello@bristolcleaningheroes.co.uk to book your winter prep. The best time is October to early November, before the really cold weather sets in. Don’t leave it until January and wonder why there’s mould everywhere.