How to stay warm on a boat

You don’t need many years of sailing experience in the UK to know that staying warm at sea is an almost year-round task.

Sure the balmy evening sails of June through August can be a delight, but the same months can still be chilly when sailing into a headwind in the rain.

Knowing how to stay warm on a boat means there is nothing stopping you from getting out there and enjoying yourself, no matter what the weather throws at you.

If you’re able to get your boat in the water early – or even keep it in year-round – you’ll extend your sailing season and be able to break the year up with some truly memorable sails.

But how do you keep your boat ready, and do you need extra kit?

How to stay warm on a boat: Maintaining your clothing

To keep yourself warm, clearly one of the main elements is your clothing.

There continue to be advances in sailing clothing.

In reality, few of us will be inclined to spend the money on a new set of foulies each season, but outer layers are now more breathable than ever and so do a better job of making sure your sweat is wicked away from your skin, keeping your inner layers dry and better at insulating.

They also have much better waterproofing properties than before and if you’re sailing in the UK, rain is always possible.

The key thing with breathable foulies is that they need to be kept clean for the breathable pores to keep working.

Depending on what yours are made from, fabrics such as Gore-Tex like to be washed in the washing machine at 40oC with a liquid detergent that does not contain bleach.

This will restore their breathability, but counter-intuitively, you will and then either need to tumble dry or iron a low heat in order to reactivate their durable water repellent (DWR) coating.

If you’ve washed them a few times, you may need to reapply the DWR coating as a washable liquid, or as a spray, and then reactivate with an iron or with tumble drying.

This step is crucial to helping the water bead up and roll off your foulies, rather than soaking into the outer fabric, which increases wind chill on deck.

It also prevents tonnes of moisture being carried down into the cabin and helps them dry out more quickly.

A good breathable sailing jacket and trousers will be of little use to you if the rest of your clothing is likely to retain moisture.

Cotton is highly absorbent and a bad insulator.

For cold weather, ideally banish cotton from your outfit.

All the big sailing companies offer breathable base and mid layers, but you don’t have to splash out.

You are looking to trap as much air as possible and eliminate draughts, without adding too much restrictive bulk.

Several thin layers are better than thick sweaters.

While synthetic fabrics are excellent at doing this, and are less absorbent and faster drying, natural fibres such as wool, and merino wool in particular, are all the rage.

Base layers made of merino are highly insulating for little bulk, as long as you keep them dry.

They’re also much more odour resistant than synthetics, and don’t shed microplastics when washed.

Thin waterproof down layers are also a extremely warm and lightweight.

A set of mid-layer salopettes will stop gaps opening up at the waist and will help keep your core warm too.

Although it is an oft-repeated fact, it is not true that a particularly significant percentage of heat is lost from your head.

In 2006, scientists tested subjects in cold water with and without wetsuits, sometimes with their heads out of water and sometimes with their heads submerged.

They found that the head accounts for about 7% of the body’s surface area, and that heat loss is fairly proportional to the amount of skin that’s showing.

At most, according to a 2008 report in British Medical Journal, a person loses 7 to 10% of their body heat through their head, again not dissimilar to what you would expect from any other exposed skin.

All that being said, there is little point in wrapping your body up in plenty of layers, keeping your core warm and not wearing a hat and, if it is particularly cold, a face mask, scarf, or a tubular neck warmer that can be pulled up.

Other extremities should be considered too, hands and feet have special blood vessels that control cooling and warming.

Some top-level athletes use special machines to help cool their core temperature and recover from heavy exercise by dunking their hands in icy water, so it is important not to neglect these.

A good pair of sailing boots should keep your feet warm and dry and provide good on-deck grip – in terms of the latter, the grip is often
provided by small slits cut into the sole (razor cutting) which is easily worn away walking on rough land, so try to limit use to on deck only.

Make sure your boots are large enough to accommodate a pair of thick socks without squeezing your feet, as this will negate the insulation and reduce blood flow.

A good pair of thermal gloves is a good idea, but they do make handling lines and tying knots difficult.

It can be worth taking a glove off to tie a knot, before drying your hands off and replacing it.

Some people take multiple pairs of cheap fleece gloves, which they find warmer than waterproof ones – and you can change them as soon as they get wet.

Contrary to popular belief, the sun does shine throughout the year and away from the summer months it’s a lot lower in the sky, which means you’ll be squinting more, so don’t forget sunglasses.

Planning food and watches

With fewer daylight hours it’s best to reduce your expectations and plan shorter sails than you would in the height of summer.

A short hop to a favourite spot is likely to be more than enough on a cold day.

If you are doing longer passages, then consider setting off in the pre-dawn so you arrive before dark, rather than leaving later and arriving when it’s pitch black and really cold – it’ll improve crew morale and safety.

Keep hot drinks in easy reach but be aware that caffeinated drinks are often a diuretic – which can be a problem when you’re swaddled up in layers.

A flask is a good way to keep ready-made hot chocolate or your drink of choice to hand.

A good supply of food will warm you up nicely. Something that can be heated in the oven is even better – things like pre-bought bread rolls, Cornish pasties or pre-cooked meals to keep the crew happy.

Think about watch rotas if you are planning a longer trip.

Though you may have a tried and tested on/off watch system, it might be worth shortening times of these in the colder months, to ensure all of your crew have sufficient time below to warm up and dry off before they are back on watch.

It’s also worth considering that with shorter days, longer passages are going to involve much more night sailing than in the height of summer.

Not only will this mean colder periods are longer, it also means more watches will be in the dark.

Night sailing is a skill and can be a great joy, but there are many factors that make things harder than sailing in the daytime.

A principal issue is concentration; it is much easier to become drowsy in the dark and we tend to have to focus a lot more to be aware of our surroundings.

Consider how long each crew-member is likely to be on watch in the dark.

How to stay warm on a boat: Crew protection

A good spray-hood is an essential bit of kit for off-season passage-making.

Not only does it offer some protection from the elements for those on deck, but it helps to keep things drier below and allows those off-watch to interact with those on deck without the need to get fully kitted up, or face the full force of the cold outside.

Make sure the windows in your spray hood are clean and transparent.

Murky windows can lead to lights, buoys and vessels being missed at night. It costs little to get old hazy windows replaced at your local sewing room.

Specialist cleaning products are available, but furniture polish also works.

From October onwards, the water temperature around the UK begins to plummet – and with it the amount of time you’ll be able to stay conscious in the water.

Cold shock can affect your ability to breathe and swim, so lifejackets are essential, as is clipping on, and minimising time spent out of the cockpit.

Again, you might want to change your standard rules onboard.

Many of us may have a ‘lifejackets on when dark, in 20 knots of wind etc’. rule.

Outside of the summer months, however, it is well worth considering the dangers of going overboard and changing your rules accordingly.

Fighting moisture

Should a spinnaker or headsail that you normally stow below get wet, it’s worth taking it home to dry it, rather than leaving it to fester and make the interior of the boat wet and mouldy.

Similarly, if your lifejacket gets wet while wearing it, open it up and dry out the innards when you’ve tied up.

Lifejackets don’t like staying damp as the automatic firing tablets can start to dissolve and the cylinders to corrode, either of which could stop your jacket working when you most need it. Remember to flush away any salt water as this will attract moisture and make metal fasteners for furry really quickly in storage.

Continues below…

When you leave the boat, with a dehumidifier on or not, it’s best to leave the cushions propped up on their sides to allow the air to flow around them, preventing them getting damp or mildewy.

All of this needs to be considered if you are sailing any time other than the height of summer.

Keeping damp and mildew at bay can be difficult unless you can be assured of a warm, dry breeze blowing through the boat.

If you can run a dehumidifier then it is well worth doing so.

If you know you are going to be leaving your boat for long stretches of time, bigger steps can be taken.

If you’re keeping your bedding on board so you can make a quick getaway, consider storing it in a vacuum bag to keep linen and duvets dry and mildew-free.

Condensation

Although sailing is in and of itself taking place in a damp environment, it is not just seawater and rain that need to be thought about.

Condensation is a fact of life on a yacht in cooler weather.

As such, you need to accept it will happen and focus on ways to combat the problem.

Condensation occurs when water vapour finds a cold surface and condenses on it, leading to a damp environment.

You don’t need a heater to sail in the spring or autumn, nor even for the winter – but it certainly makes life much more comfortable on board.

An oil-filled radiator can be left on overnight, which will not only make things warmer, but also reduce condensation if you also introduce some ventilation.

Away from marinas, there are options for dry heat.

The most common is one of the diesel forced air heaters made by companies such as Eberspacher, Webasto or Wallas.

These use the boat’s diesel tank and run from the battery.

A diesel heater shouldn’t be left on all night (the batteries are unlikely to thank you) but they are great for keeping boats warm and dry.

Other heaters include kerosene and meths heaters.

Improving insulation can reduce condensation, but insulating the hull can involve a lot of work.

If you insulate the inside of the fibreglass hull with a product such as Celotex or another insulation, and then stick headlining over the top, the boat will stay warmer and dryer in winter and cooler in summer.

If you’re replacing your headlinings at any point then this might be a task worth considering to improve your sailing comfort in the future.

A cockpit tent means you can keep the companionway open a touch and thus keep condensation at bay – without letting huge amounts of cold air into the boat.

In rain and even snow, it means you can keep wet sails and clothing outside and generally make the boat more habitable.

Boat windows are both a major source of heat loss and, consequently, a prime candidate for condensation.

One trick is the one used by Yachting Monthly contributor Brian Black, who created his own removable double glazing for his windows to keep in the heat and fight off condensation woes.

Mooring

Pontoons grow moss, algae and lichen outside of the summer months and can get very slippery.

Consider scrubbing yours clean, using a decent decking cleaner, many varieties of these are available and increasingly you can find cleaning products designed for marine use containing no toxic chemicals, which will prevent harm to marine life.

After washing make sure you do a final scrub with salt water, as the salt then left in the surface grain of the wood will make it less likely to ice up if the temperatures are particularly low.

If your boat is going to be in the water in the spring, or particularly the autumn and winter, consider the increased likelihood of storms when leaving your boat.

Check that your mooring lines are up to the task and that you have some built in redundancy to your mooring and tying up just in case bad weather does appear.

How to stay warm on a boat: Spring

Rain is a big factor in spring sailing and will work to quickly make you cold if you are not properly dressed to keep the rain at bay.

Make sure your clothing is properly watertight and fits properly around the neck to reduce the chance of water getting in.

Sailing in warmer weather, you will still want to be dressed to keep the rain out, but this may make you too hot and sweaty.

Breathable clothing will help in this situation and it is worth considering a high-wicking thermal base layer – merino wool is a good option – and not wearing any mid layers as the extra warmth may not be required.

The temperature can fluctuate significantly from day to day, so you’ll want to take everything in your kit bag to make sure you are prepared for all conditions.

Cold water shock is a real danger in the spring.

This is the time of year when the difference between air temperature and water temperature is at its greatest.

Make sure you have an appropriate lifejacket rule in operation: a MOB casualty at this time of year is potentially fatal and it is likely the person in the water could lose consciousness quickly.

How to stay warm on a boat: Summer

The key issue in the summer is the disparity between day and nighttime sailing.

In the UK, even during a hot spell you are likely to be cold on deck at night.

Make sure you plan ahead and take suitable sailing kit with you, even if it is going to be hot and sunny.

Don’t dismiss the cumulative effect of windchill when going from downwind to upwind.

If you’re running at 5 knots in 10 knots of breeze and turn upwind, at 4 knots you’ll experience around twice as much wind as you had previously.

Consider putting on more layers before turning upwind as it is much easier to then take a jacket off than it is to warm yourself up once cold.

How to stay warm on a boat: Autumn

Try to plan any sailing with a view to getting to your destination while it is light.

Daylight hours start to disappear quickly from October and nighttime sailing can be a cold experience.

It’s better to set off pre-dawn and arrive while the sun is up and you are warm, rather than arriving cold and tired to a destination at night.

Bear in mind that you are more likely to be sailing in windier conditions than other times of the year.

Make sure your spray-hood is in decent condition as it becomes an invaluable spot to shelter from the worst of the weather while on deck

How to stay warm on a boat: Winter

Condensation can be difficult to deal with when sailing in the winter.

It is a fact of life – we constantly create moisture just by breathing – but steps can be taken to minimise condensation or dry the boat out after use.

Try not to leave things to dry below and remove or cover soft furnishings below when leaving the boat.

A cockpit tent is a good option so you can leave things to dry on deck overnight.

Try and take plenty of hot drinks and foods that can be easily heated.

Little beats the comfort of something hot in the belly on a cold winter’s day.

Consider altering your watch system to shorter stints and allow crew plenty of time to warm up below between watches.