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Boat Winterizing Mistakes

Why boats get damaged during winter, and how to protect them

By Bob Adriance

A BoatUS member in Rye Beach, New Hampshire, reports that whenever he winterizes his boat, he always feels a mixture of regret and apprehension. Regret because he must bid adieu to yet another boating season. Apprehension because he always has a vague feeling he's forgotten to do something – something important that could wreck the boat.

Winter isn't kind to skippers who are absent-minded. Engines get ruined. Boats sink. Seaworthy examined 40 BoatUS Insurance claim files to discover the most common mistakes skippers, absent-minded or otherwise, make when they winterize their boats. Hopefully, the list will jog a few memories and avoid a lot of unnecessary anxiety.

Winterize your boat - BoatUS Magazine

Failure To Drain The Engine Block

Of the 40 claims that made up the survey, which state would you guess had the most freeze-related claims? New York? Maine? Vermont? Guess again. Balmy California had more winterizing claims than any other state, including any of the "deep-freeze" states. While winters may be much colder in the deep-freeze states, the bitter temperatures are a fact of life and preparations for winter are taken very seriously. But in more temperate states, such as California, Florida, Texas, and Georgia, winter tends to be relatively comfortable with only an occasional cold spell. As one Sacramento, California, skipper said, "We don't think much about freezing weather because it never happens. Well, almost never."

It's interesting to note that all of the claims in temperate states involved boats that were being stored ashore. Water retains heat longer than air, so boats surrounded by air are more vulnerable to a sudden freeze than boats surrounded by water. Even in temperate states, boat owners must winterize engines, especially when boats are stored ashore. In deep-freeze states, boats stored ashore must be winterized earlier than boats stored in the water, lest an early cold spell crack the block.

Failure To Drain Water From Sea Strainer

Seven of the 40 insurance claims were related to an often overlooked piece of hardware down in the boat's bilge called a sea strainer. A sea strainer is located in the engine's raw-water intake line to filter out debris before it gets to the engine. If the engine is winterized by opening petcocks to drain water out of the block and manifold, the strainer must also be drained or residual water could freeze and rupture the watertight seal. In three of the strainer-related claims, the boats sank when the seacocks were opened in the spring and water began trickling in through the ruptured strainers. In the remaining four claims involving sea strainers, the boats began sinking as soon as the ice thawed because the intake seacocks had not been closed.

Failure To Close Seacocks

Open thru-hulls below the waterline left unprotected either caused or contributed to the sinking of seven boats in the sample group. Leaving a boat's seacocks open over the winter is like going on an extended vacation without locking the doors in a house. Neglecting to "lock" even one "door" is a significant risk. If a thru-hull below the waterline can't be closed, either because it's broken or mechanically frozen open, a boat should be stored ashore for the winter. The sole exception is cockpit drains, which must be left open and should be inspected to make sure the hose clamps (two at each connection is recommended) are in good shape.

It should be noted that thru-hulls above the waterline are not required to have seacocks, and most don't. That doesn't mean that these thru-hulls aren't vulnerable. One boat sank and another had its engine wrecked when thru-hulls near the waterline were submerged by the weight of snow and ice in the cockpit. Plastic thru-hulls deteriorate — become brittle — in sunlight. If a fitting just above the waterline has cracked, the boat should be hauled out for the winter and all of the plastic fittings should be replaced with bronze or Marelon. Check to make sure that hoses near the waterline have loops, which are necessary to prevent back-siphoning.

Clogged Petcocks

Two claims involved engines whose petcocks, which are used to drain water from the engine, had been clogged by sand or other debris. In one of the claims, the boat had grounded shortly before it was winterized and the surveyor discovered the engine's cooling system was full of sand that had been sucked up through the intake. In the other claim, the petcock had apparently been blocked by rust. In both cases, water remained in the engines and froze, which cracked the blocks and ruined the engines.

A petcock that doesn't drain properly when opened should be probed with something like a coat hanger. If that doesn't work, you can unscrew the petcock and try again. If all else fails, you can call a mechanic or use the engine's intake hose to flush nontoxic antifreeze through the engine's cooling system.

Leaving Open Boats In The Water Over the Winter

Boats with low freeboard are also vulnerable to the weight of snow and ice in the cockpit. One boat sank and another was damaged when the sterns were shoved under by accumulated snow. While a well-supported cover would certainly help, the most effective solution is to store boats with low freeboard ashore for the winter.

Using Bimini Covers As Winter Storage Covers

There seems to be a common misconception that a cover that protects the crew from glaring sun will also protect the boat from freezing rain and snow. Quite the contrary; Biminis tend to get ripped apart or, more likely, age prematurely from the effects of winter weather while doing absolutely nothing to protect the boat. A bona fide winter cover, on the other hand, is terrific protection. Three of the 40 claims involved expensive Biminis that were destroyed over the winter. Biminis should be stored inside the boat over the winter or, better yet, taken home for cleaning and safekeeping.

Other Common Mistakes

Some "unusual" claims speak for themselves. One was for a hose in the dockside water system that froze and split, eventually sinking the boat. Why, you might ask, would someone leave the fresh-water system hooked up over the winter? Good question. The owner didn't have a good answer. Another boat was "pushed" underwater by a combination of slack dock lines and rising tides when it got caught under the dock. This can happen anytime, but is more likely to happen in the winter when tides can be exaggerated by blustery winds. Dock lines, spring lines, and fenders should be used to keep the boat well away from a dock. All lines should be protected against chafe.

Boatyards

While the 40 winterizing claims involved mistakes made by the skippers, the problem of boats blocked incorrectly by boatyards is certainly in evidence in the BoatUS Insurance claim files. Boats stored ashore should be supported by a cradle or by jackstands tied together with chains and supported with plywood bases so they won't sink into the mud or asphalt. Jackstands (at least three on each side for boats longer than 26 feet) should be positioned at the bulkheads, with blocks used beneath the boat to support the engine and keel. Some boats have specific requirements for support of things like keels; if the marina manager isn't familiar with your boat, check your owner's manual or contact the manufacturer. In all cases, boats stored ashore should always be level.

Two claims were filed by skippers who stored their boats on trailers. The trailers were cocked forward and both boats were damaged by pooling water. A similar problem occurs when leaves block cockpit drains. In two other claims, precipitation found its way below, wrecking cushions, woodwork, and even an engine. The best defense against any type of damage is to visit your boat periodically over the winter, even if it is stored ashore. Make arrangements with friends to watch out for each other's boats so that someone will be checking on your boat regularly.