Q: I’m planning to have my boat covered professionally and leave it in the water over the winter in my regular slip. The idea is to have a place to go and hang out with my friends during the winter months, sort of an on-the-water man cave. Is there anything special I need to do to make sure my boat’s engines and systems are properly winterized while in the water?

This is a question I get asked fairly often. Lots of people leave their boats in the water during the winter months but there are some precautions that need to be taken, especially if you are not going to be visiting the boat on a weekly basis.

In the water storage does require some special attention to detail, especially if you live in a climate where the water may freeze.

Under cover, boats in the water can provide an escape from daily shoreside life—even in the offseason.


First of all, if you live in an area where the water around the boat is likely to freeze, see if the marina uses ice-eater pumps to keep the water around the boat circulating. This will prevent ice formations around the hull that could be quite damaging. If you are able to visit the boat on a very regular basis (say daily), one trick is to make sure the boat is secured properly with strong dock lines and spring lines in a fore and aft orientation and run the boat in gear at low speed. The prop wash will circulate the water and help to prevent heavy ice from forming. I used to use this technique on a boat even after ice had formed and it was pretty amazing how quickly the prop wash would clear it out from around the boat.

But please, before you attempt this procedure, make sure the boat is properly secured with good sound cleats and dock pilings. You don’t want to drive the boat up onto the dock.

As for systems, make sure any sacrificial anodes on the boat or engine drives get replaced now to ensure that they’ll last the winter. It’s also a good time to carefully inspect your shorepower cord and dock pedestal for any signs of corrosion or overheating at the plug socket and terminals. You’ll probably be running some sort of electric heater on the boat while you are on board and these units draw a heavy amount of electrical current. You need this system to be in top notch condition to make sure no problems crop up due to the heavy current draw.

Your boat’s fresh water system should be drained as it will likely freeze up, causing extensive damage. Winterize just as you would if you were stored on the hard, and bring bottled water for visits.

All of your batteries should be brought up to a full charge and make sure all bilge pumps are in good working order. Some people will sprinkle salt in the bilge to keep water that ends up there from freezing, but I think this is a waste. There is only about a 3 or 4 degree difference in the freezing point between salt water and fresh water. (32 degrees F for salt, 28.4 degrees for fresh.)

Your marine head holding tank should be completely pumped out. Pump some environmentally friendly anti-freeze through the system. You can use the system through the winter, as long as you use enviro-friendly anti-freeze when you flush into the holding tank. And remember that a pump out in February might be a bit hard to come by. Most marinas that allow in-water winter storage or have year round live-aboards also have facilities on land, and it’s better to use those.

As for the engines, just make sure the oil has been changed before the winter begins. Check the coolant freeze level on the closed side of the cooling system to make sure it is adequate to about -25 degrees F. The engines will be fine in the water over the winter otherwise.

Enjoy those winter escapes to the boat!