Winterising your boat - Pro tips from YDSA

Post by: TheYachtMarket News
27 November 2017


More boat owners are wintering afloat. Perhaps you are tempted by off-season berthing deals, or want to avoid the cost and hassle of lifting-out. YDSA, the UK’s professional association for yacht designers and surveyors, has compiled a handy guide to ensure you get back on the water as quickly as possible next Spring.


Three good reasons to remove non-essential items

  • Cushions, clothing, charts and books will harbour damp
  • Removing electrical equipment will extend its life
  • It’s sensible to have less kit on board in case of a break-in

Remove your sails and covers

Some sails are left on for years – genoas rolled-up with only the UV strip to protect them and mainsails where tatty covers are the only thing stopping them being blown-out in a gale. Take them off and get them serviced, it will cost you less than doing it in the spring.


Decommission the engine

  • Check that the water intake and hose are in good condition and not left open
  • Check that the stern gland isn’t weeping
  • Add insulation around the engine. Make sure it’s not a fire risk and don’t forget to remove it before re-starting
  • If your engine has indirect cooling, make sure that suitable antifreeze has been added to the system
  • Always totally fill the fuel tank at the start of the winter. Excluding air helps prevents the condensation that leads to the growth of diesel bug
  • With small tanks of around five gallons, it’s best to dispose of the fuel at the end of the winter, flush the tank and then refill. Otherwise, when you recommission the boat, drain off a small amount from the base of the tank
  • Check that the O-ring makes a good waterproof seal on the filler cap.

Outboard Care

Take it home, flush it well with clean water, and dry fully. Try to dispose of the fuel rather than let it go stale for next season. Or use specialist zero-ethanol petrol on the last run to protect the fuel system from waxing-up.


If there is a means of keeping the batteries charged by shore, solar or wind power, that’s good practice.  Check the terminal joints are clean and dry to help reduce any unwanted draining.


Maintain Ventilation

Take care when maintaining a good flow of air – if this is not done properly, water will find a way in and undo all the good you’ve done.  Dehumidifiers are increasingly popular but domestic units aren’t designed for the marine environment - be sure you are not creating a fire risk.

Reduce Condensation

If you have shore power, a small tube heater with a frost thermostat is a great help in reducing condensation and stopping things from icing-up.

Water Storage

Completely drain down anything that stores water, including pumps, calorifiers, water-makers, filters and accumulators.  Freezing ice is strong enough to crack an engine block.


Protect the decks

Ensure the deck and deck-fittings are watertight before any snow falls. Some owners prefer to use a custom-made deck cover.

Check your skin fittings

Check the condition of all through-hull skin fittings, valves, clamps and hoses.  Where possible, shut them off.  Inboard, the main job is to prevent icing. Drain the heads bowl and pump of any water. Iced-up cockpit drains can cause trouble. So, if you fit a heater with a ‘frost’ setting to reduce condensation, locate it well and kill two birds with one stone.

Hatches & Portholes

Make sure all of the gaskets on hatches and portholes create proper watertight seals.


Check your insurance

Not all insurers will cover craft on swinging moorings over the winter, so check your policy carefully.


Ensure you notify the marina, yard or moorings operator, particularly if you leave your keys with them, that your boat has been winterised just in case they are tempted to turn it on and move it.  It also means if they see anyone hanging about they will investigate or contact you.

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