Winterizing A Twin Engine Boat: Step-By-Step Guide

Winterizing a twin-engine boat is a crucial process to protect your boat from damage during the cold months. It involves a comprehensive set of steps to ensure the boat and its engines are ready for storage and shielded from the harsh winter weather. From draining water lines to changing engine oil, there are several essential procedures to follow.

The first step is to flush and drain all water lines, including the engine cooling systems and plumbing, to prevent water from freezing and causing damage. Next, you should replace engine oil and fluids, such as coolant, steering fluid, and transmission fluid. It is also important to inspect and replace fuel lines if necessary and grease all moving parts.

Another critical step is to protect the internal engine components. This can be done by using a fogging spray or oil, which coats the components with an anti-corrosive compound. Additionally, it is essential to clean the boat thoroughly, including the cabin, heads, kitchen, and helm, to remove any dirt and grime.

Finally, you should prepare the boat for storage by using a pressure washer and an acid-based hull cleaner if needed. Apply waterproofing to the canvas and wax to the exposed fiberglass surfaces.

By following these steps, you can ensure your twin-engine boat is properly winterized and protected during the off-season.

Clean the boat thoroughly

To prepare your twin-engine boat for winter, you must clean every inch of the boat thoroughly. This means cleaning every nook and cranny before the boat goes into storage.

First, inspect the hull for any structural damage. Check the bow eye for stress cracks and gel coat blisters. If you find any, consult a professional. Scrape off barnacles and other residues from the bottom of the boat. Sand away any remaining residue and use a pressure washer to remove other dirt and grime. Once the hull is clean, use marine paste wax to create a protective acrylic shield on the hull surface, which will prevent dirt from penetrating the wax.

Next, drain all parts of the boat that hold water, including the bilge pumps, livewell pumps, and raw water washdowns. Run these until they are completely dry. If there is water in areas that cannot be drained, add antifreeze.

To protect vinyl interiors, use vinyl cleaners and protectants to prevent cracking and drying out. Spray chemical dehumidifiers inside the boat to prevent moisture buildup, which can lead to mildew. To improve airflow, vent the cover of your boat.

Additionally, to protect the boat's electrical system, remove and store electronic items in a safe place away from winter conditions. Spray exposed electrical connections with a moisture-resistant lubricant.

Finally, conduct a thorough cleaning of all interior areas of the boat, including the deck, transom, stern, galley, berth, cabins, head, and helm. Vacuum and wash carpets and floors, ensuring that everything inside the boat is clean and bright.

Prepare the engine for winter storage

The engine is the most important and expensive feature on your boat, so it's crucial to ensure it's properly winterized. Here are the steps to prepare the engine for winter storage:

• Grease lubrication points: Grease all the moving parts of the engine.
• Apply a corrosion barrier: Apply a rust inhibitor spray or a corrosion barrier product to prevent corrosion, especially if your boat is used in saltwater.
• Prep the engine for storage: This includes various tasks depending on the type of engine and specific boat.
• Prepare the fuel system: Store your boat with fresh fuel treated with a marine fuel stabilizer. Untreated fuel can oxidize and form a gum-like substance in the engine's fuel system. Run the boat for about 10 minutes to get the treated fuel into the entire fuel system. Finally, replace the fuel filter.
• Change the oil and filter: Storing the engine with old oil can expose internal components to moisture and acidic combustion byproducts, leading to corrosion. Change the oil and filter, then run the engine again to check for leaks.
• Treat with fogging oil: Treat the engine with fogging oil to prevent corrosion. Remove the spark plugs and spray the fogging oil directly into each cylinder.
• Change the gear lube: Check and change the gear lube in the outboard lower unit. Water in the gear lube can freeze and expand during storage, potentially cracking the gearcase.
• Check the prop shaft: Remove the propeller and check the prop shaft for any fishing line or debris. Coat the prop shaft with a quality marine grease before reinstalling the propeller.
• Check the power trim fluid: Check the power trim fluid level and top it off if necessary. If the fluid is pink or milky, it indicates the presence of water, which could mean a leak in the system.
• Check sacrificial anodes: Sacrificial anodes protect the engine's submerged metals from galvanic corrosion. Check and replace them if they are more than 50% deteriorated.
• Lubricate grease points: Lubricate any grease points or zerk fittings on the engine.
• Store the engine upright: Trim the engine down to its vertical position so that any remaining water can drain out. This is important to prevent water from freezing and causing damage.

Drain the fuel tank

Draining the fuel tank is an essential step in winterizing your twin-engine boat. This process helps to prevent fuel-related issues that can cause problems when you take your boat out of storage in the spring. Here's a detailed guide on how to properly drain the fuel tank:

• Understand Your Boat's Fuel System: Before beginning, it's important to familiarize yourself with your boat's fuel system. Refer to your boat's owner's manual to identify the location of the fuel tank, fuel lines, and any other components involved in the fuel system.
• Remove Fuel from the Tank: Start by draining the fuel from the tank. This can be done by siphoning or pumping out the fuel into an appropriate storage container. Be sure to follow local regulations for fuel storage and disposal.
• Clean the Fuel Tank: Once the tank is empty, it's a good idea to clean it to remove any built-up residue or contaminants. Use a fuel tank cleaning solution or solvent specifically designed for marine fuel tanks. Follow the instructions on the product, as different cleaners may have varying application methods and dwell times.
• Inspect the Fuel Tank and Lines: Take this opportunity to thoroughly inspect the fuel tank and fuel lines for any signs of damage, corrosion, or leaks. Pay close attention to areas where leaks commonly occur, such as seams, connections, and fittings. Replace any damaged or worn components.
• Treat with Fuel Stabilizer: Before refuelling, it's crucial to treat the tank with a fuel stabilizer. Fuel stabilizers help prevent the fuel from degrading and losing volatility during storage. They also inhibit the formation of gum and varnish deposits, which can clog fuel lines and injectors. Be sure to use a marine-grade fuel stabilizer and follow the manufacturer's instructions for proper application.
• Refuel with Fresh Fuel: After applying the fuel stabilizer, refill the fuel tank with fresh, high-quality fuel. It is recommended to use ethanol-free fuel, such as REC-90, which is specifically formulated for recreational engines. Fill the tank to approximately 95% full to allow for fuel expansion during temperature changes.
• Run the Engine: Once the tank is refuelled, start the engine and let it run for a while. This will help circulate the stabilized fuel throughout the entire fuel system, including the fuel lines, injectors, and carburetor.
• Replace Fuel Filters: Finally, replace the fuel filters and fuel/water separators. Old filters can contain contaminants that can damage the engine, so it's important to install new ones before storing the boat for the winter.

By following these steps, you'll help ensure that your twin-engine boat's fuel system is properly prepared for winter storage, reducing the risk of fuel-related issues when you're ready to take your boat out on the water again in the spring.

Protect the interior and cabin

Winterizing the interior of a boat with a cabin requires more time and effort. The following steps will help protect the interior and cabin of your twin-engine boat during the winter:

• Clean and condition vinyl surfaces: Use a marine vinyl protectant to polish vinyl surfaces and protect them from drying and mildew. This is especially important for vinyl deck seats and chairs, which can dry out and crack quickly during harsh weather.
• Prepare storage areas: Clean drawers, cabinets, and storage areas thoroughly. It is not necessary to remove all items, but leaving these spaces open will prevent them from smelling musty and mouldy when you open them again after several months.
• Clean and disinfect appliances: Ensure you clean and disinfect the refrigerator and freezer. Remove all items and pay special attention to these areas to avoid any unpleasant surprises when you return to your boat in the spring.
• Pump out and flush the head: Pump out the head, flush it with fresh water, and then add antifreeze. Pump the antifreeze through all the hoses and valves to ensure they are also protected.
• Drain and flush freshwater systems: Drain the freshwater systems and hot water heater. Disconnect and then reconnect the lines on the hot water heater, and flush the system with antifreeze. Finally, fill the water heater with antifreeze to protect it during storage.
• Remove and store cushions: It is a good idea to remove any removable cushions and store them indoors during the winter. This will help keep them in good condition and protect them from potential damage.
• Pest control: Install pest repellents to prevent pests from making your boat their home during the winter months.
• Ventilation: Ensure your boat has adequate ventilation to prevent moisture build-up and the development of mildew. Spraying chemical dehumidifiers can help with this.
• Cover sharp corners: To prevent wearing through the cover, place padding on sharp corners, such as those around windshields.
• Protect electronics: Remove valuable electronics and store them safely to protect them from potential damage during winter storage.

Check the exterior and trailer

Inspecting the exterior and trailer of your twin-engine boat is an important step in the winterization process. Here are some detailed instructions to ensure your boat is properly prepared for winter storage:

• Check the Hull: Inspect the bow eye for any stress cracks or gel coat blisters. If you notice significant cracks, it is recommended to consult a professional to assess for potential structural damage. Scrape off any barnacles or other build-ups on the bottom of the boat. Sand down any remaining residue and use a pressure washer to remove stubborn dirt and scum. After cleaning, apply a marine paste wax to create a protective shield that will prevent dirt from penetrating the hull surface.
• Bilge, Livewells, and Raw Water Washdowns: Drain all parts of the boat that hold water, including bilge pumps, livewell pumps, and raw water washdowns. Ensure that all water is completely removed and run these systems until no more gurgling sounds are heard. If there are areas where water cannot be drained, be sure to add antifreeze to prevent freezing.
• Protect Vinyl Interiors: Vinyl interiors are susceptible to winter conditions, so it is important to use vinyl cleaners and protectants to prevent cracking and drying. These products are available in spray and gel forms.
• Prevent Moisture Damage: Spray chemical dehumidifiers inside the boat to prevent moisture buildup, which can lead to mildew. Ventilate the cover of your boat to allow for good airflow and reduce the chances of trapped moisture. Additionally, spray exposed electrical connections with a moisture-resistant lubricant to protect them from moisture damage.
• Clean Interior Areas: Conduct a thorough cleaning of all interior areas, including the deck, transom, stern, galley, berth, cabins, head, and helm. Vacuum and wash carpets and floors, aiming to clean and brighten everything inside the boat.
• Drain and Treat Water Systems: Drain all heads, tanks, and sinks, and run non-toxic antifreeze through them. Open all valves and faucets to empty the freshwater tank completely. Close the faucets and valves, and add antifreeze to the tank. Open the farthest faucet or valve and wait for the antifreeze to flow out. Repeat this process for all water systems, heads, and systems that hold water.
• Pest Control: Install pest repellants to prevent pests from taking up residence in your boat during the winter.

Frequently asked questions