How to Cover Your Boat

Nothing is harder and less appealing than having to lug a heavy canvas up a ladder and then trying to spread it over a boat. But this is one of the annual rites of fall in northern boating regions. The sad thing is that many people go through all the work of covering their boat, yet get very little result for their effort.

A boat cover should come off when you want it off, not as the result of a winter storm.

A winter cover is supposed to protect the boat. To do the job, it should keep water, snow and ice out, yet not encourage excess condensation, which will lead to mildew. Most importantly, the cover should last through the entire winter. And it should come off when you want it off, not as the result of a winter storm.

Should you cover your boat?

Putting boats into a canvas cocoon started in the pre-fiberglass days. Fresh water in the bilge is a mortal enemy of wooden boats, because it allows the growth of the dreaded (and mis-named) dry rot. A dry wooden boat is a healthy wooden boat, so it is natural for owners to go to great lengths to protect against winter snow and ice.

Fiberglass boats don't rot. Why, then, do we still go through the agony of covering them? The answer is a combination of tradition and necessity. Tradition is the real driving force behind winter covers. Boats have always been covered, so we feel like we're not treating our fiberglass right unless we cover it.

Necessity is also a factor, though only boats with non-draining cockpits or cabin doors that are not weather tight absolutely need winter covers to protect them from short term damage. Generally, these are the same boats that need summer covers to keep rainwater from collecting inside.

Virtually all sailboats and most larger powerboats have scuppered, self-draining cockpits and weather tight hatches or doors. Snow and ice are no more likely to enter in the winter than rain is during the summer. So, is a winter cover absolutely necessary?

This thought occurred to me after visiting several boat builders during winter months. Invariably, I would see active molds outside in the snow. Many times there would be ice inside these molds. Yet, the builders assured me these molds would not be damaged by winter weather.

"Ice and snow don't hurt them," the builders would say. "What really hurts is the ultraviolet light from the summer sun."

Sure enough, when I checked through the literature on fiberglass maintenance, I discovered this is the truth. Modern fiberglass resins are pretty much impervious to water, ice and snow. But ultraviolet light causes the gel coat to lose its color and turn chalky.

When is your boat subject to ultraviolet light damage? Is it during the short, dark days of winter or the long, sunny days of summer? The answer is obvious. Summer kills fiberglass boats, not winter.

So, last winter I decided to experiment. I left my custom-made framework in the garage. I didn't buy a new cover to replace the one that wore out the previous winter. Instead, I left my 29-foot sailboat completely uncovered beneath the winter sky.

When it snowed, by boat was covered in white. A spring ice storm put a glistening sheath over the deck that no gel coat could hope to match. Whatever the weather concocted, my boat shrugged it off.

I own a Bayfield 29 sailboat. This model is easily identified by lots of exterior teak, including a taffrail with turned spindles. All winter I wondered what would happen to that teak. Would spring find me with unrepairable damage to all that wood?

At first, things looked pretty bad. Without a cover, my boat got far dirtier than ever in the past. The teak was actually black. You could see grain only where the Deks Olje had actually weathered completely off the wood.

A water hose and a bucket of soapy water quickly cleaned the deck. Next, I tackled the teak with one of the two-part cleaners, just as I have done every spring since purchasing the boat. Miraculously, the teak cleaned easier after a winter's exposure to the elements than it ever had. The rich, golden color came back with little scrubbing and the surface was as smooth as if I had sanded it.

So my experiment was a complete success. There was absolutely no winter damage from leaving my boat uncovered. In fact, the weathering of the teak may have made it easier to clean, not harder. Sure, the deck was dirtier, but it's dirty every spring. I would have had to wash it anyway.

So, do I recommend not covering your boat?

Not necessarily.

On shore, some boats will collect water in various recesses or scupper pipes that will not drain naturally. This is because the boat may not sit on the cradle at the same angle as it does when floating in the water. Freezing water expands. It can burst pipes or cause other damage.

You will have to do a thorough survey of your boat before abandoning it to the elements. If you have any doubts about damage from freezing water, cover your boat.

How to Cover Your Boat

A sloppy job of covering is worse than none at all, which is why so many owners ask the yard to shrinkwrap each year. You can do the same job with a canvas or plastic tarp, as long as it never collects snow or water. This means the cover needs some sort of supporting framework.

Traditional wooden frames are expensive, clumsy and time-consuming to build. They are also difficult to store. Recently, several companies have begun marketing clamps which allow you to custom-build a frame out of steel electrical conduit. These frames are easy to store and erect year after year. Plastic pipe can also be used to build a framework in a similar manner.

The cover must fit tightly and not flap in the wind. A flapping cover can wear itself out in one or two storms. Worse, winter-long movement of the cover or the tie-down ropes against fiberglass can scratch or completely wear through the gel coat. Those brass grommets are extremely effective gel coat destroyers when propelled by a 40 knot wind.

Plastic or Canvas?

Plastic tarps cost a lot less than canvas. Most expensive to purchase are custom-fitted covers of real canvas. So which are the best value?

Because they never fit exactly, plastic tarps always flap in the breeze. Good quality plastic will last a full winter, but by spring there will be worn spots and the grommets will have begun to pull out of the hem. You might a second winter out of a good plastic tarp, but definitely not three.

Canvas tarps are heavier, so they don't flap as much. Sun rot and chafe along the ridge pole and other projections in the framework are the enemies here. Still, a good quality cover will last up to four seasons or more.

A fitted canvas cover flaps the least, lasts the longest and is the most expensive to buy. It must be mated with a framework that can be rebuilt every year. But the protection is superb.

A good canvas shop should turn out a fitted cover that virtually never flaps, even in high winds. Sure, it will move in the wind, but not flap around like an ordinary tarp. This means less likelihood of fiberglass damage from tie-down ropes, grommets or the canvas.

Patching and repairing a fitted cover is a reasonable expense. This is not true of a canvas tarp which may cost less to replace than the repairs. Plastic tarps cannot be repaired, so must be replaced when damaged.

Shrink wrapping has become popular because it does a great job of sealing out the winter, but it's not a DIY project.

Shrink Wrap

Technology has brought us another means of covering boats: shrink wrap. Boat builders initiated the use of this plastic material to protect new boats while they were being shipped via truck. Now many companies offer shrink wrapping services to the ordinary boat owner.

Shrink wrap requires special, expensive tools, which is why owners generally ask for help. Also, a shrink wrap top is somewhat expensive. And, it is difficult or impossible to re-use a shrink wrap cover. You must buy a new one each season, and hope that the boat yard recycles the old plastic each spring.

On the good side, shrink wrap covers don't flap. They virtually cannot cause chafe, scratches or wear to the fiberglass. They cover so well that decks emerge nearly as clean as they were the day the boat was covered. Learn all about Shrink Wrapping a Boat.

Fitted Covers: Worth the Cost

In the long run, a fitted cover and its supporting framework are probably the most cost-effective way of covering your boat. Over eight or ten winters, you'll spend a lot more on plastic or canvas tarps than you will on a fitted cover. The only problem is coming up with the money to cover the initial cost.

If cost is a factor, consider combining the concept of not covering your boat with the advantages of a fitted cover. Have a professional make a cover for only the portions of the boat which require protection. Leave the rest uncovered.

A friend of mine covered just his main hatch last winter. The rest of his boat was left uncovered. The hatch required covering because of ventilation louvers which keep out rain but would allow snow to enter.

His experience was similar to mine. The uncovered portions of the boat suffered no damage. Perhaps the best part of the story concerns his wallet. That small hatch cover cost a lot less than an overall cover.

Air Circulation

Both of us discovered a real advantage of leaving our boats uncovered. The ventilators that keep both boats well aired during the summer continued to work all winter. Last spring, the insides of our boats were sweet smelling, thanks to that air circulation. Covers can prevent adequate air circulation and encourage mildew.

What's the right way to protect your boat? Only you can answer that question. But, it pays not to be a slave to tradition. Choose the covering system that works best in your situation.