Tips for winterising your boat

Tips for winterising your boat

To avoid any unpleasant surprises for you come the new season, we’ve put together some tips and recommendations on winterising your boat. Properly winterising your boat is essential to avoid damage. There are some general rules you should follow:

Underwater hull

If you store your boat in a dry berth, the first thing on the list after craning your boat out of the water is jet-washing the underwater hull including driveshaft, props and rudder. Don’t wait until algae or shells become touch dry. Cleaning promptly will save you money, time and effort. Best is to remove any underwater growth from the hull, propeller and rudder regularly as the season moves on. After cleaning and drying, you should check for and repair damage such as rust areas, hull blisters or cracks. If you are not sure that what you are really dealing with is osmosis, it is prudent to involve an expert for moisture testing.

Engine and generator

The good condition of engine coolant and oil is key for preventing all sorts of damage. Freezing water in the cooling cycle or acidic engine oil residue can cause damage that you can easily avoid with only little technical means. Ensure that you have the proper mixture of antifreeze in the cooling system. Let the engine idle at least 15 minutes after you topped up on antifreeze so that it distributes evenly after the thermostat opens. If you have a closed cooling system, you should check the sacrificial anodes. If they are depleted, you need to replace them. Ideally, you schedule your oil change before winter layup. The colour of the oil will tell you a lot about how watertight the cooling system is. Milky or cloudy oil is a sure sign that water leaked into the oil circuit. Have an expert check this. In addition to conventional engine oil the use of storage oil is recommended. This will double the cost and work, though, since you will have to change it again at the start of the season. The oil change should of course go hand in hand with replacing the oil filter. You can carefully blow out your air filter with compressed air if it is not too dirty. Also check the tension of the V-belt.

Propulsion system

Regular transmission oil changes will also extend the service life of the propulsion system elements. With shaft propulsion systems, you check the oil level while the boat is driving. Hence you change the oil before your last boat trip of the season. Boats with sterndrives have a rather complicated oil change procedures, so you might want to involve an expert. If your boat is equipped with a saildrive, checking for oil discoloration is particularly important:

milky white colour means that the watertight seal around the drive leg, or shaft seal, is defective and water already leaks into the hull.


Check if the stuffing box is watertight: there is nothing worse than water in the bilge. If water already enters when the boat is not in motion, then tightening the gland nut is a good idea. Stuffing boxes normally leak water at a rate of one drop per minute when at sea. No leakage must occur when the shaft is stopped, though. Better attach a warning at the helm to prevent the shaft from jamming at the start of the season.


Check whether the hose connections seal properly and, if necessary, tighten the hose clamps. Replace corroded hose clamps, if any, and test the ball rotation if you have a ball valve seacock. Ball valves should be half open for winter layup (of course, only in port).

Electrical system

Maintenance of the electrical system consists mainly in lubricating the poles. Since most batteries are maintenance-free, there is no need to check the electrolyte level and top up any water. Just tighten any loose cable connections.


A bilge pump can literally be a lifesaver. You should therefore regularly trigger the float switch and test operation of the pump.
Warning: don’t let your bilge pump run dry for too long, otherwise the impeller might get damaged. One essential winterising habit you should get into is to check the impeller. Always carry replacement impellers on board. Neoprene impellers are recommended since they have a longer bearing life. Check manual bilge pumps for free movement and correct operation.

Freshwater and sewage holding systems

Particular attention should be paid to the sanitary systems. You can’t leave any water in the system or it might freeze, expand and crack or burst the tubing. As a rule, drain all tanks and tubes including the water heater, if any, disconnect the lines (and possibly blow them using compressed air), open all faucets and flush and rinse the toilets.


While gas systems should generally be handled by a specialist, the skipper should inspect the lines and pressure controllers for corrosion and keep them clean. Remove all gas bottles from board before the winter layup.

Life rafts and lifejackets

Ensure that life rafts are inspected and maintained two years. You need a specialised company for that. Mind the expiration date! Personal flotation devices and buoyancy aids which are pill-activated should be checked every two years and the pills replaced. Also, spare pills on board come in handy. Check CE certification and approval markings on lifebuoys and lifejackets, especially when you are cruising in Italy where they take CE conformity quite seriously.


Regular windlass checks and annual maintenance are recommended. The anchor windlass requires special attention since it is exposed to seawater. After only two years, you might no longer be able to unscrew the cover since aluminium screws expand upon contact with salty water.

Deck hardware

You need to inspect the attachment points, surface and sealing of fixtures. Dismantle the hardware and replace the sealing if it is spongy or cracked.

Windows and portholes

You should check threaded connections for proper torque, replace spongy and worn out gaskets and treat intact gaskets with a care product.

Fuel tank/fuel systems

Corrosion inhibiting fuel additives reduce water condensation in the tank over the winter and prevent the growth of diesel bug. The minimum you should do is clean the fuel filter. Top up your tank to about 95%, reducing the chance of condensation adding water to the fuel and leaving room for expansion.

Boat cover

A sturdy, weatherproof tarp will protect your boat’s deck and superstructures. Make sure to tie the cover down well. Mount cover poles or rope constructions as upright as possible allowing snow and water to run right off to prevent pooling issues.

Sacrificial anodes

All zinc anodes at shaft, prop, sterndrive, rudder and trim tabs need to be checked. As a rule of thumb, anodes should be replaced at least once a year and earlier of course when you see signs of erosion.

Lines and superstructures

The connection between land and boat goes neglected more often than not. Checking the ropes for signs of damage such as fraying is vital though. This is also a good opportunity to count all your ropes and lines. Inspect deck organisers, sheaves and mechanical travellers for wear and chafe. Only use non-aggressive grease or lubricants on blocks and sheaves. Carefully dry your sails before you pack them up for storage. Check turnbuckles and cables for signs of fatigue cracks and remove corrosion, if any.