Winterising top tips

Lay-up your boat for winter with our handy checklist
 

“When putting your boat to bed for the winter there are a few things to consider to protect it through the winter months”, explains Chief Instructor, Sail and Motor Cruising, Vaughan Marsh. 

“In simple terms, you need to either remove anything that could be damaged by freezing and damp, or you need to mitigate against that happening.

“Boats contain a multitude of systems that hate inactivity – particularly the engine. Therefore the best way to winterise your boat is to continue to use it,” says Vaughan.

Whether you plan to continue using your boat during the colder months or to lay her up ashore, read on for Vaughan’s top tips for looking after your boat this winter.

Vessels left in the water

If you do decide to leave your boat in the water ready for use, there is potential for freezing and damp and you will need some form of protection such as: 

  1. Run the engine reasonably often, preferably in gear and preferably while enjoying the quiet marinas and anchorages away from your home berth.
  1. Use electric heater/s with a thermostat set to above freezing both below deck and in the engine bay.
  1. Set up a dehumidifier draining into the sink (not to a tank).
  1. Keep an eye on the power supply. This could be as simple as daily visits, or you could set up a monitoring system to alert you of low temperatures or should the power drop out.

    A smart plug with a sim card can notify a mobile device of loss of power and can also, in some cases, be used to monitor temperature and even restart electrical devices.

    NB: If you don’t have access to, or would rather not use power to heat/prevent freezing and or damp, then much of the winterisation check list below will be useful.
  1. Keep fuel tanks topped up.
  1. If the vessel has an external shower, drain down the water and isolate it from the fresh water system.
  1. Add extra mooring lines. Go to the vessel often and check and adjust them to change the potential chafe point.
  1. Clean the outside of the vessel.
  1. Empty any clothing, bedding and foodstuff not needed.
  1. Consider emptying fridge(s), doing a deep clean, turning off and leaving slightly open.
  1. Check all through hull fittings for leaks and corrosion.
  1. Check your stern glands and repack with grease if appropriate. Note, there are many versions of stern gland so you will need to research this and ensure that you comply with the manufacture’s recommendations.

Vessels ashore or not used (winterisation)

Many of the points above are still valid, but in addition:

  1. If you’re taking the boat out of the water make sure it is angled with the bow slightly upwards to enable rainwater to run off immediately from covers, decks and cockpit.
  1. There are plenty of other items that would benefit from winterisation but if you only do one thing, do it on the engine:
  • First on the list - general engine cleaning and observation. Shine plenty of light, use a mirror on a stick or a digital camera to see under and behind things. Dry the bilges to prevent corrosion and if necessary, paint them white to highlight any leaks and drips in the future.
  • Whether your boat is being hauled out for the winter or not, fill your fuel tank to prevent condensation, which in turn prevents the growth of diesel bug.
  • Change the engine oil and replace the oil filter before leaving your boat for the winter.

    Leaving the old oil contaminated with the acidic by-products of combustion inside the engine block will shorten the engine’s life and a neglected oil system will cause expensive damage.

    Also consider using flushing oil or a flushing additive during the oil change which helps to remove more of the contaminants.
  • Check the gearbox or outdrive oil and replace if it looks cloudy or milky.
  • Most diesel engines use raw water cooling which needs attention when winterising.

    Raw water systems require draining before leaving for the winter, by closing the water inlet valve, or sea cock, disconnecting a hose from the circulating pump (unless there is a dedicated tap or plug), then refilling with a strong solution of fresh antifreeze.

    Run the engine to fully circulate the new solution. Simply draining the system is unlikely to remove all the water inside, which may, then freeze and cause damage over the winter.
  • Check the water pump impeller and consider replacing it when de-winterising in case the blades have deformed over the winter.
  • Remove the air intake filter and block the intake with an oily rag to prevent rust inside, do the same for the exhaust. Squirt a little oil into the intake and turn over the engine, (without starting), to distribute it over the cylinder walls. Be sure to place a warning about the blocked intake on the engine control panel to prevent anyone turning the engine over.
  • Where possible, remove the batteries and keep them warm and dry over the winter, fully charged or topped up at least every four to six weeks. Batteries left uncharged for long periods may need to be replaced completely.

    If you’re unable to remove batteries or if the boat is staying on its mooring, leave them fully topped up and regularly recharged, as full batteries are less likely to freeze in sub-zero temperatures.
  • Relax or remove all belts and protect the drive wheels. Rust on these can chew up a belt very quickly in the new season.
  • Many engineering companies will winterise your vessels engine(s) for you if some or all of above is something you would prefer a professional to do. 
  1. Covers should keep water out but allow air to circulate. Proper through-draught will prevent condensation which leads to dry rot, mould and corrosion (especially if left for more than a single season).
  1. The internal freshwater supply system also requires attention. Drain the entire system including tank, pump, calorifier, water filters and all taps especially shower mixers.

    Look for any areas where water could still be trapped in pipes. Plastic piping is less vulnerable than copper piping but rigid unions can still be damaged by freezing.

  2. If you have a water-based central heating system using antifreeze then it can be left alone providing they contain the correct water/antifreeze mixture. This can be checked using a strength tester available from marinas and good car spares outlets.

    Note that antifreeze has a limited life and if it has to be replaced then it is a good time to replace any suspect hoses. Keep the old hoses as emergency replacements.

    If the system doesn’t use antifreeze then it should be drained as for the freshwater supply.

  3. Remove any foodstuffs which may be damaged by the frost or attract unwanted ‘visitors’ such as mice and rats.

  4. Store all linen, clothing, blankets, curtains etc. ashore – washed and dry. Prop the fridge door open – mould will form in less than a week if left closed. Ensure through-ventilation. Leave cupboards and drawers open; prop up bunk cushions, leave under-berth locker lids open. Get circulation into every possible conceivable nook and cranny.
  1. Ensure tight-fitting covers for deck-installed electronics and consider spraying behind electronics with water-repellent silicone. Check your navigation lights are still serviceable.
  1. Make a list of what you have done to winterise the boat so you remember what to reverse in the spring and leave signs all around the boat so no-one accidentally operates a winterised system.

Finally - protect your investment. Whether the vessel is lifted or left in the water it will still need frequent visits to ensure all is well. A weather eye still needs to be maintained and prior to any strong winds the vessel will need checking and securing.

Bilges will still need to be pumped and any deck items checked for security and serviceability. If in the water extra lines may be needed, lines will need to be adjusted often to prevent chafe, fenders will need to be checked and adjusted and a check everywhere to ensure no unwanted guests have moved in for the winter.

Find out more

The one-day RYA Diesel Engine course will help you prevent and solve diesel engine failure, covering basic maintenance and engine care including winterisation.

Shoreside learning

The RYA Diesel Engine Handbook is essential reading for leisure boat owners. Available as both a book and eBook with easy to follow text and detailed illustrations, the digital version is also enhanced with animations and video content (RRP £18.99, Members’ price £16.14).

To find out more about RYA books and courses visit rya.org.uk/training.