Dewinterize Your Boat With These Steps
Updated: Sep 28
Here in Northern California, as valley temperatures start creeping up into the 70s as early as February, it's easy to start thinking about getting back on the water to cruise, fish, wakeboard, wake surf, and waterski.
But before you launch your boat, there may be some de-winterizing tasks to take care of.
De-winterizing your boat is not the exact opposite of winterizing your boat, as there are some tasks that are best done before you store your boat for the winter — and therefore don't need to be done later.
So, what things should you do to de-winterize (a.k.a. summerize) your boat? Let's 'summarize' various items that should be taken care of to properly 'summerize' your boat.
Remove the Boat Cover
The first step in de-winterizing your boat is to take the cover off. This allows for air to circulate and helps to dry your boat out.
Some boat owners recommend using large folds rather than rolling your cover off.
If you had placed even an inexpensive de-humidifier in your boat for the winter, you'll be one step ahead.
If you stored your boat outside for the winter, check for any signs of critters that may have gotten into your boat and left a mess or caused damage.
Inspect, Clean, and Repair Your Boat's Vinyl
Inspect your boat's vinyl for any damage.
You can clean and protect your boat's vinyl with a specialty vinyl cleaning product. Meguiar's is a popular brand of marine vinyl and rubber cleaner. 3M is another brand that's used by many boaters.
You can also use a specialty sponge to remove any stubborn stains.
These types of specialty marine products will both remove stains — including mildew stains — and provide UV protection.
Change the Oil if Necessary
It's best to change your oil and filter before you store your boat for the winter. But if an oil change was not part of your winterization process, this is a suggested de-winterization task.
If your boat has been sitting in the winter, the oil may have thickened into sludge.
Be sure to use the correct type of oil for your boat engine. Consult your owner's manual or talk to a marine mechanic if you’re not sure which type of oil to use.
Be sure to change the oil filter at the same time.
Inspect Your Boat’s Electrical System
The electrical system on a boat can be damaged during the winter months. Be sure to check the electrical system for any obvious signs of damage.
A full electrical inspection involves an extensive checklist. Here are just a few checklist items.
Make sure that all your navigation lights are functioning correctly. Keep note of any light bulbs that need replacing.
Look for any wiring insulation that may have melted. Melting can be caused by wires that have an excessive load. Wires that come in contact with a hot engine can also cause the insulation to melt.
Check your Boat’s Battery
As part of de-winterizing your boat, you should check your battery to make sure it’s in good working condition.
A reasonably priced battery tester can give you a good overall analysis of your battery's health.
If your battery is slightly weak, it may under-supply components like your bilge pump. If it's very weak, it may not be able to start your boat's engine.
Check the battery connections and make sure they are tightly secured. Clean the contacts and coat them with petroleum jelly.
If you need to replace your battery, this is a good time to do it. Be sure to fully charge a new battery before you use it.
Check the Fuel System
Inspect your fuel lines for any damage. Make sure any fuel lines that have been exposed to UV light have not gotten too brittle. Check for any cracks in the lines.
Over time, ethanol and UV light can degrade fuel lines and result in the collection of debris inside the lines. Debris can block the fuel flow to the engine, especially at high throttle.
A fuel filter with a clear casing will give you a visual sign of debris.
Debris from fuel lines can also get into the fuel pump. Unless you're fairly handy, disassembling and cleaning a fuel pump is a task best left to a marine mechanic.
Inspect your gas tank for any corrosion or other damage. Replace the tank if necessary.
Inspect the Bilge Pump
Bilge pumps are susceptible to a variety of problems including debris in the intake and in the impeller. The impeller itself can sometimes break or come loose. Sometimes the discharge hose can get clogged.
The other problem can be wiring connections and too little voltage.
Here's a full article on troubleshooting a bilge pump.
Inspect and Refill your Cooling System
Check for any cracks in your cooling hoses and for any loose connections. Replace worn hoses.
Refill your cooling system with soft water. Use distilled water if your local tap water is hard - i.e. it contains a lot of dissolved calcium and magnesium. Add a cooling system inhibitor to help protect the system from corrosion.
Here is some comprehensive information about freshwater cooling systems.
Check Out Your Boat Safety Gear & Equipment
It's important to check your boat's safety gear and safety equipment before you start using your boat again.
Check the condition of your life jackets, fire extinguisher, sound signaling device(s), and other safety gear. Inboard motors are required to have a working backfire flame arrestor.
Here is a complete list of California safety regulations for motorboats in the 16-foot to 26-foot range.
A safe boating season starts with making sure that all of your safety gear is in good working order.
Clean the Distributor
The distributor is an important part of the engine and should be cleaned regularly. Be sure to clean the distributor every time you de-winterize your boat.
Use a wire brush to clean the inside of the distributor. Be sure to remove all of the dirt and debris.
Lubricate the moving parts with a light coating of oil. This will help keep the distributor functioning smoothly.
Inspect the Distributor Cap
Problems with your boat's engine might be due to a faulty distributor cap. The symptoms of distributor cap problems can be rough idling or stalling.
The worst case is that your boat's engine might not start at all.
Often, the easiest solution is to replace the cap, since it's a relatively inexpensive part.
Wash Your Boat's Hull
Many boat owners swear by a product from Better Boat called Instant Hull Cleaner. to remove film and stains from their boat's hull. Better Boat's products are eco-friendly.
Make sure your boat's hull is dry. Use a pump sprayer to spray the cleaner on your boat's hull. Let it sit for about five minutes and then hose it off with a garden hose. You can optionally use a soft-bristled brush for stubborn stains.
Check the Thermostat & Water Pump
The service interval for pumps and thermostats generally ranges from two to three years.
If a thermostat gets corroded or clogged, the result can be an engine that overheats. In the worst case, the engine could seize.
When a thermostat is stuck in the open position, the engine may not reach a proper operating temperature. This can negatively affect your boat's engine performance. It may result in an over-consumption of fuel.
Check the thermostat along with the water pump for signs of wear or damage.
Check for Worn or Loose Belts
An important thing to check when de-winterizing your boat is the condition of the belts.
If you have a loose alternator belt, here's how to tighten it.
Do a Trailer Check
It's important to do a trailer check before you start using your boat again. Be sure to check the condition of your trailer's tires, brakes, and lights.
Check your trailer's rollers to make sure they all still have a smooth action. Check for any signs of cracks in the frame.