How and Why You Need to Winterize Your Boat?

Winter can bring disaster for your boat and its components when left unwinterized. Any boat owner wouldn’t want to encounter problems with their vessels when spring comes. That’s why winterizing your boat is crucial to prevent it from getting damaged during the winter season.

What are the Factors to Consider in Winterizing your Boat?

Any boat owner wants to ensure that they will have a suitable running vessel by spring. Here are the important factors you need to consider when winterizing their boat:

  • Pulling your boat out of the water or not
  • Winterizing the outboard engine
  • Winterizing the inboard or stern-drive
  • Winterizing plumbing, air conditioning, and sanitation systems
  • Best way to cover your boat
  • Looking out for your fuel and its systems
  • Protecting your batteries
  • Other minor issues that arise when you winterize a boat

How to Winterize a Boat?

Winterizing a boat is crucial to have a vessel that works perfectly in time for spring. How to winterize a boat should be a breeze with these easy-to-follow steps:

Step 1: Ready your boat engine and ensure that you drain and remove all of the water.

Step 2: Coat the engine with corrosion protection.

Step 3: Check the owner’s manual for precise instructions, and complete fogging, if necessary.

Step 4: Fuel can degenerate in about two months, which can cause gumming and staining on your engine. It could lead to the engine’s poor performance and shortened life span. To rectify this issue, incorporate a fuel-stabilizing additive into the fuel system, then run the engine afterward.

Step 5: Change the boat engine’s fuel filters. Do the same thing with any fuel/water separators in the fuel system.

Step 6: Exude your boat’s freshwater plumbing systems, including heads, sinks, and tanks.

Step 7: Integrate antifreeze into the boat’s plumbing systems.

Step 8: Make sure to remove the water from all other systems. It includes livewells, bilge pumps, raw water washdowns, and others.

Step 9: Pull out drain plugs. You’ll find these in the engine block and manifold.

Step 10: Cover your boat and station it into winter storage, and assure that the place is dry. Remove any valuables, electronics, or gadgets. You can also shrink-wrap your boat.

Why Do You Need to Winterize Your Boat?

As the water freezes and expands, it can destroy what’s trapped inside. Water may permeate exposed spaces, letting in acidic and oxidizing wastes. Salt can also enter, and corrosion buildup can wear away delicate engine parts.

Each of the boat’s systems can go wrong, and if you don’t act now, you might encounter the following problems:


Regardless of what kind of boat engine you may have, not draining the water from the engine can cause a damaging effect.

Cracks and Breakage

If you don’t drain your boat’s raw water and fresh water-cooled engines, it may cause cracks and breakage. Saltwater becomes frozen and can expand into closed spaces even at lower temperatures. A hose may split open or blow a hose off its fitting. In a worst-case scenario, the engine itself will be wasted.

On the other hand, freshwater-cooled engines with insufficient anti-freeze can likewise freeze and crack. Using only water for cooling increases the risk. To prevent such risks, use a mixture of anti-freeze and water.


Left-over water in hoses can lead to burst lines, while showers and sink fittings will crack when water is left to freeze. A pump that’s left wet will break once it becomes frozen. Also, it will destroy itself if operated while frozen. Unemptied holding tanks could freeze and expand, while waste will dry out and harden over the winter.

Heat exchangers and hot water tanks experience the same destructive effect of water expansion, shattering of tanks, and heating elements when left unwinterized. Closed fixtures with water in it may freeze and rupture.

Dirt and Corrosion

Filthy oil consists of acidic contaminants and salt, which can cause a multitude of issues with corrosion. Forgetting your boat engine’s oil unchanged and engine unflushed might not harm the engine itself in an instant. However, it can still ruin your engine, shorten its life, or decrease efficiency. Fogging and cleaning the engines can rectify the problem.

The same thing goes with a mechanical system that’s left with dirt and caustic waste products clung to them. Even if your boat rests in a heated garage, the absence of motion in the engine can develop issues where the dirt sits. This happens when you don’t change the oil or flush the engine.

Fuel Issues

Gasoline will degrade because of various weight compounds that segregate and evaporate. If the fuel contains ethanol, it can absorb water left for the winter. Fuel oils are generally produced from different crude oils and refinery processes. Because of their incompatibility, they can sometimes become unstable upon mixing.

Additionally, diesel poses unique risks, such as algae growing in it, resulting in clogged injectors and filters. Unlike brimful of biocide-treated fuel tanks, half-full or empty tanks are more susceptible to biological growth.

Mold and Mildew

A boat with no proper ventilation confines moisture that results in mildew formation, mold, and decay. Sealing the boat for the winter is one of the many ways to winterize a boat. However, not doing it right will leave a bad-smelling vessel for spring.

On the other hand, an exposed boat will amass dirt over the winter season. If you park your vessel beside a tree, there’s a tendency that it will have brown stains, dirt, and piles of rotting leaves, let alone a stained deck. Pollution can likewise leave a mark on your uncovered boat where dust, dirt, and grime might build up.


Marine batteries, otherwise known as boat batteries, also need maintenance just like your car batteries. More often than not, they’re neglected when winterizing the boat. Lead-acid batteries, such as AGM and Gel, will discharge themselves over time. Not fully charging the batteries as the winter arrive will shorten your boat batteries’ lifespan.

Meanwhile, Lithium Iron Phosphate batteries have their own storage problems. When storing, they must be 50% discharged while disconnecting all loads. Though they don’t freeze like lead-acid batteries, their capability minimizes at low temperatures, and charging it below 32°F (0°C) will compromise the batteries.

Frozen Keel or Bilge

Your boat may sink if it has a frozen bottom when there’s enough water in it. When thru-hulls become frozen, they can get severed or inoperative underneath the waterline.

Deck Fittings and Hardware

Water can enter the boat from everywhere. Uncovered vessels with snow and ice-covered decks may allow water to get through stanchion bases, deck fittings, and other areas unprotected from the harsh elements.

Deck sections surrounding the fittings may crack, allowing the water to seep below and behind openings and fissures. Water can permeate windows, between their seals, or between the hull and window.

Storing Your Boat for the Winter

Before the winter sets in, you should have already decided where to store your boat. Some might put them in their garages, while others will leave them on the water, significantly larger boats. Storing your vessel in the water over the winter has some typical issues, including:

  • Preventing your boat from corrosion
  • Staving off ice formation around the boat
  • Winterizing freshwater systems and holding tanks
  • Keeping a heat source inside the boat, when necessary


Winterization processes keep boat systems and gear from damage due to freeze. Likewise, it protects batteries, inboard/outboard motors, lower units, and sterndrives from destruction lying idle for several months.

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