The ultimate winterisation checklist for boats and outboards

As the boating season winds down and colder months approach, preparing your vessel for winter is essential. Winterising your outboard engine protects its performance, longevity, and value. At The Wolf Rock Boat Company, we specialise in servicing boats and outboards, offering expert winterisation and secure storage solutions to safeguard your investment.

Whether you're a seasoned boater or new to marine ownership, this guide answers the key questions about winterising your outboard engine.

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Why is winterisation so important?

Failing to winterise your outboard can lead to:

• Corrosion of internal components

• Fuel degradation and clogged injectors

• Freezing damage to the cooling system

• Costly springtime repairs

Water expands by about 9% when frozen, exerting up to 30,000 psi of pressure, which can crack engine blocks and gear housings. Ethanol-blended fuel also absorbs moisture, leading to phase separation and varnish buildup in carburettors and injectors.

According to the Royal Yachting Association (RYA), proper winterisation ensures reliable performance and prevents expensive damage.

What do you need before you start?

Gather these essentials:

• Fuel stabiliser

• Fogging oil

• Fresh engine oil and filter 

• Gearcase lube and pump

• Flushing muffs and freshwater hose

• Marine grease for moving parts

• Battery charger or maintainer

How do You winterise an outboard engine?

Here’s a practical, step-by-step checklist:

1. How do you flush the cooling system?

Attach flushing muffs to the water intakes, connect a freshwater hose, and run the engine for 10 minutes to remove salt, silt, and debris. This prevents corrosion and blockages.

Tip: Tilt the engine fully up and down to drain residual water.

2. Should you change engine and gear oil?

Yes. Old oil contains contaminants that can corrode internal parts. For 4-strokes, change the engine oil and filter. Replace gear lube in the lower unit to prevent freeze damage if water contamination is present [RYA].

3. Why add fuel stabiliser?

Fuel can degrade in as little as 30 days. Add a marine-grade stabiliser to a nearly full tank and run the engine for 10–15 minutes to circulate treated fuel through the system [Quicksilver].

4. What is fogging and why do it?

Fogging oil coats internal engine parts to prevent rust during storage. Spray into the intake while idling until the engine stalls, then into each cylinder via spark plug holes.

5. Which moving parts need lubrication?

Grease the propeller shaft, steering components, and throttle linkages. Remove the propeller to check for fishing line or damage [RYA].

6. How should you store the battery?

Disconnect and remove the battery. Store it in a dry, frost-free place and charge periodically to maintain health [Quicksilver].

7. How do you protect the exterior?

Clean and wax the engine cowling. Avoid plastic wrapping, which traps moisture. Use a breathable cover for the boat and engine [Yacht World].

8. Where should you store the boat?

Choose a dry, ventilated space. If outdoors, use a quality cover and ensure proper drainage. Professional storage services often include security and climate considerations [Practical Boat Owner].

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What winterisation services does The Wolf Rock offer?

At The Wolf Rock Boat Company, we provide:

• Suzuki Outboard Servicing – as an Approved Suzuki Marine Outboards Agent

• Winterisation and Winter Storage – combine engine care with safe storage

• Trailer Service & Repair – essential for safe transport

• Tube Service & Repair – for RIBs and inflatables

• Paddle Board Repair – including authorised Red Paddle repairs

Our in-house team of qualified marine engineers operates from fully equipped workshops in Salcombe and Churchstow, ensuring your boats and outboards are in expert hands.

Ready to winterise your boat?

Don’t leave your boat exposed to harsh winter elements. Contact The Wolf Rock Boat Company today to book your winterisation service or learn more about our support packages for boats and outboards.

Visit our services page or call us directly to speak with our friendly team.