Put your boat away ready to go and come spring you are at the boat ramp instead of the boat mechanic. Simple as that.

We call it winterization, but it doesn’t exactly matter how cold it’s going to get, or even if it will snow at all. If your boat is going to sit unused for a prolonged time, you need to prepare it for storage. Doing so will play a big role in getting the maximum lifetime out of your boat and all the equipment aboard it — not to mention ensuring next season starts smoothly for your boat.

The convenient route is to drop it off with your local boat mechanic and pick it up shrink wrapped if you like. But the DIY path is not that hard either.


What’s the Problem?

Water. Water and time. Water and subfreezing temperatures. Water condenses out of the air, and then is given time and/or subfreezing temps.

Also: critters, salt deposits, leaves, and other debris, and the sun’s damaging rays.

Fuel System Maintenance 101

Winterization is not entirely about prepping your motor to sit idle for months and then spring to life in a heartbeat when called upon — it’s just mostly about that. The first objective here is to bring any internal combustion engines on your boat through a long storage in ready-to-go condition.

The first thing to do is consult your owner’s manual. The manufacturer of your motor probably also has more detailed advice and how-to’s on their website.

Your owner’s manual probably advises draining the fuel system for best results, but that’s a tall order for the average DIYer. The more practical alternative for most boat owners is to condition the fuel that will remain in the system over the storage period.

Drained Fuel System

Short of draining your fuel system, here are the major components for prepping boat motors for winter are:

  1. Fill the tank
  2. Change the fuel filter
  3. Change the fuel/water separator
  4. Add fuel stabilizer
  5. Change the engine oil and oil filter
  6. Fog the engine
  7. Hit all the grease fittings

Non-Drained Fuel System

If you are not draining the fuel system, then you want to do the opposite: fill it to minimize the volume of moisture-bearing air circulating into your tank by way of the vent. Aluminum fuel tanks are prone to condensation, and ethanol-blended gas increases the problem, due to the hydrophilic nature of ethanol.

If you have access to it, using ethanol-free gas in your boat is always a good idea, but especially before extended storage. Don’t overfill the tank; leave some space for thermal expansion of the gas in it. Fill it to just short of full, about 7/8 of a tank.

Engine Care Essentials

Also, change out all fuel filters and fuel/water separators. Remember, the goal here is to eliminate moisture and contaminants from the fuel system, and these components are designed to capture them.

Next, add fuel stabilizer. One way to ensure that your tank has the right volume of stabilizer, and any other additives you regularly use, is to get your gas at the pump in gas cans and add your additives there. Then you can feed your tank and motor(s) a consistent, well-mixed blend. Always run your engine(s) for at least five or 10 minutes to circulate stabilized fuel throughout.

Always change crankcase oil on four-strokes to get rid of any moisture accumulated during the season. Gear case lubricant should be either changed or carefully inspected for signs of water intrusion. If you find any evidence of water in your lower unit, change the oil.

The goal is to eliminate moisture and contaminants from the fuel system.

Regarding fogging, opinions and recommendations vary, and your owner’s manual might not say anything about it at all. While it may not be absolutely necessary, fogging oil will help prevent corrosion inside your engine.

Most manufacturers also recommend a spray-down under the cowling with a product to repel moisture and prevent corrosion.


We have lots of spendy electronics on our boats these days. The season’s end is a good time to make sure everything is in good shape. Check wiring and clean connections. Wipe display screens clean with microfiber cleans. Optimally, move inside for winter storage anything that can go.

All batteries lose charge over time. It can take half a year or more for a good AGM battery to deeply discharge and need resuscitation, but deeply discharging a battery can damage it, especially in freezing conditions. Batteries should be charged to full and, ideally, trickle-charged monthly or kept in maintainer mode.

All that is most easily done by leaving them on the boat, though moving batteries to cool but not freezing storage is optimal.


If you are not overhauling hubs and bearings at this point, give the hubs an inspection and pump fresh grease through if necessary. Jack the trailer up off its wheels so that the tires don’t sit loaded one way all winter.

This also takes the load off the suspension. If your boat is going to live outside through the winter, covering the tires and moving trailer-mounted spares inside is not overkill.

A Good Time for Maintenance and Cleaning

It’s very easy to give yourself all winter to take care of a few issues on the maintenance list and then get caught trying to get it all done right before the first time out next season. 

As you’re prepping for winter storage, it’s also a good time to knock out the bigger jobs that come along irregularly, like lifting your boat and pulling the trailer for wiring and bunk maintenance, or suspension work.


Drain anything left with water in it. Outboard cooling water drains by itself when the engine when tilted down (in the running position), but inboard and I/O cooling systems must be manually drained. Drain livewells, baitwells, and associated plumbing. Hit the bilge pumps briefly to be sure they are dry.

Store motors in the full down position to allow them to fully drain cooling water and stay fully drained in areas like the prop hub.

Cleaning up a boat thoroughly is an important part of putting it away for a few months, particularly if there are salt deposits. Once your boat is washed up, you might as well wax it. Then hit the chrome and any other metal surfaces with WD40 or another protectant.

Before you leave your boat for a long winter nap, make sure the bow strap and any other tie-downs are relaxed and not holding the boat tightly to the trailer. 

Wrap It Up?

A boat sitting outdoors for the winter needs to be covered, and it’s not a bad idea to keep a garaged boat covered either. A traditional cloth cover is good, but shrink wrapping provides significantly better protection against moisture and pests and is more resistant to damage from wind and other weather.

Shrinkwrap can damage some painted hulls.

You can get your boat shrink-wrapped professionally, or you can gear up to do your own shrink-wrapping and break even after a few winters, depending on how much material you go through in the process of learning to do it well.

So, should you shrinkwrap your boat? Shrinkwrap can damage some painted hulls, so how a boat with such a paint job is shrinkwrapped is one detail to be attentive to.

The big thing is, again, water. A shrink wrapped boat will be as impervious to the elements as an outdoor-stored boat can get, but that goes two ways: any moisture that does get into a poorly ventilated shrinkwrap installation is going to find excellent conditions for resulting in mold damage. The bottom-line: shrink wrapping offers excellent protection when it’s done right.

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