How to winterise your boat engine

As winter approaches, it’s essential to properly winterize your boat engine to protect it from freezing temperatures and potential damage. This step-by-step guide will help you ensure your boat engine is ready to perform flawlessly when the boating season returns.

No matter what sort of boat you have, all fuel systems will need some individual attention. Always start by referring to the engine manual. Even though winterising your engine shouldn’t be complicated, each manufacturer has slightly different methods and there may be some specific actions required for your engine model.

A guide to winterizing your boat engine

Disconnect the battery and store in a warm dry place and charge ready for spring.
Store engine with the leg down so any water can drain freely.
Top up fuel tank and add fuel stabilizer.
Use fogging oil in plug ports or wherever the manufacturer states.
Lubricate the engine and grease moving parts to prevent corrosion.
Cover the engine to reduce dust and any knocks and leave some ventilation so no condensation forms.

Many boat owners believe the best way to winterise an outboard is to run the engine every couple of weeks for long enough that the engine reaches normal operating temperature. This is a valid view as problems with outboards are down to the outboard not being used rather than the effects of low temperatures. If you’re prepared to commit the time and are able to access and run your outboard engine through the winter then simply running the engine may be your best route.

Winterising an inboard engine

Winterising an inboard engine is similar to a stern drive engine. The only difference is where a boat remains in the water for the winter you’ll need to run antifreeze through the engine by closing the intake seacock, removing the intake hose and putting it in a bucket of antifreeze.

Whilst you’re looking at the engine have a look at the propellor and the propellor shaft for any damage or debris. If you can, re-grease the prop shaft.

Winterising a modern boat engine should be fairly straightforward, however many boat owners also take the opportunity to check over the engine for wear and tear. At this point many boat owners, particularly those who have invested in expensive engines, will use the services of a qualified marine mechanic.