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A simple guide to winterising your boat

Updated: Aug 14, 2020

When the nice, sunny boating days are going and winter approaches, it is a good time to start thinking about winterising your boat and motor.

It’s also a good idea if you’re storing your boat for a long time, which is the situation we unfortunately find ourselves in now.

This quick guide to winterising your boat helps you to preserve the condition of your motor and boat, so when the sun starts shining you can get straight out there!

Treat these guidelines with caution - if you're a beginner or unsure about anything we always recommend getting a qualified professional to do the work. A good one will even show you how to do it if you ask nicely...

But just quickly, before we start:


As an alternative to winterising your boat, you can run it every 4-6 weeks with ear muffs or flushing tank for 10-15mins per engine.

While you’re doing this, make sure to also check your steering (if hydraulic check for leaks as well).

If you can't or don't want to do that here's a basic checklist for you:


Fuel is an important factor in the running of your engines.

Fill the fuel tank with fresh fuel and put in a fuel additive (this will keep the fuel from going off for up to 12 months).

If old fuel is left untreated for a long time (six months+) some of the fuel will begin to oxidise and form a gum-like substance. If you try and start your outboard with the old, stale fuel it can leave deposits in your engine combustion chamber. Over time these deposits build up and reduce your engine performance.

Alternatively if you have a smaller tank, some people choose to leave a small amount of fuel in the tank over winter and simply drain the old fuel and fill the tank with fresh fuel before using the boat again. The old fuel will still be suitable for the lawnmower so it won’t go to waste!


There are different ways to fog or winterise your engine. If you’re from a mechanical background you can do this yourself, however

we strongly recommend that you get your marine mechanic to winterise your engine.

There is a risk of something going wrong (it's not as simple as it sounds) and causing damage that's costly to repair.

Some outboards have an auto setting, which we can set in the workshop on a laptop or others can do it manually with instructions using the control box operation.

Other ways are to run the engine and get it up to running temperature, remove the spark plugs (again – this should only be done by a qualified mechanic) and spray a fogging oil into the cylinders.

You should also:

  • Check/replace sacrificial anodes

  • Check throttle, steering and power trim cables

  • Spray engine and electrical connections with water repellent

  • Check hoses, belts and replace fuel filter


Changing the oil helps to prevent any moisture build-up in the boat’s internal system.

This will reduce the chance of corrosion and other problems that can cause issues with your engine power, impact on fuel economy and in the worst case cause total engine failure.


Batteries left over winter without charging can cause you problems when it comes to spring and boating season starts again.

It’s best (if you can) to remove the battery from the boat and store in a cool, dry spot and charge regularly to maintain good battery life.

If you can't then disconnect the batteries and use a portable charger to charge them regularly.


Lubricate all grease nipples and grease points. Grease steering cables and leave steering arm out so it doesn’t seize the motor.


Ideally your boat should be stored under cover (a boat cover or shed) to protect it from the elements. This will protect the internal furnishing of the boat and not let water sit in the hull if it rains. It'll also help to keep it clean (inside and out).

It’s also important to have some airflow to prevent mould and mildew build-ups.

Before putting it under cover you’ll need to give it a thorough clean. Clean and wax the hull to give it a bit of extra protection, and thoroughly scrub the interior to make sure you’ve gotten rid of any old bait or other stuff that’ll smell rotten after a couple months. Leave cabin doors slightly ajar to maintain a bit of airflow and remove anything from the boat that holds moisture (cushions, life vests, towels etc.). This way you’ll have no nasty surprises when you whip the covers off in Spring.

If you don’t have a secure shed to store your boat, we also recommend removing any electronics to prevent theft.


Often forgotten about, your trailer lives a hard life as well. Before storing for winter check the trailer bearings and service if need be.


Not that we really need to encourage you to spend some time in the shed with your boat, but after particularly bad weather or every four weeks, just do a quick check to see that no mould or mildew is appearing or that there is any moisture.

You can even tell your wife that we’re saying you HAVE to…

Following the guidelines above will help you preserve the condition and performance of your boat through the winter. And when the sun does come out (or the Covid-19 restrictions are lifted) you'll be on the water at a drop of the hat!



Do you have a question you want answered? Feel free to submit it and I'll answer it in depth for you.


Do you need to service your boat? Our team of technicians at Edencraft Marine have over fifty years experience in the industry. We're still yet to come across a problem we can't solve!

Feel free to get in touch via (03) 4216 5411 with any service enquiries.

As Geelong's only Mercury dealer we also have a full range of Mercury outboards and Mercruiser's for all your repower needs.

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