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Honey, I Shrunk the Boat (But Theres a Little Problem...)
By badriance - Published January 21, 2009 - Viewed 3452 times
Shrink-wrap (low-density polyethylene or LDPE) has been a boon for boaters since its introduction. It protects boats from pretty much everything a boat needs to be protected from -- snow, rain, dirt, bird droppings, and even the sun. Because it’s formed to the hull, it can’t blow off and though LDPE can puncture (not easily), it doesn’t tear like fabric. A typical 23-foot boat can be sealed drum-tight against the elements in two or three hours for a lot less than the cost of a traditional boat cover. The stuff is even recyclable. It’s no wonder that thousands of boats every year are protected with shrink-wrap.
But along with all this good stuff are a few precautions; shrink-wrap doesn’t breathe, which can cause problems, and if it’s not installed with care, a boat can be damaged or even destroyed. Not all boat finishes can withstand being in contact with a plastic film that doesn’t breath. Awlgrip, a company that manufactures two-part polyurethane paint for boats, specifically warns against using shrink-wrap, stating that it may result in loss of gloss, blistering, or delamination of the topcoat. This is confirmed by marine surveyors who often report areas of bubbling underneath the shrink-wrap on painted hulls; even boats with gel coat can get blisters if water is trapped by the wrap. Vents may need to be installed to allow for air circulation -- the same stuff that keeps dirt and water off the boat can keep in moisture, causing mildew. The same thing can happen when a shrink-wrapped boat is plugged-in to keep the batteries charged; normal gassing is trapped inside and in the event of overcharging, the boat can be filled with fumes if there is no outlet. It’s also important not to block gasoline vents since fumes from gas, expanding as the weather warms, can be forced into the boat. The number of vents required depends on the size of the boat -- three for smaller boats and as many as eight for larger ones should be adequate. More serious problems can occur from a careless installation.
Boats need some sort of underlying structure to support the shrink-wrap and prevent pockets that can trap water. Not only can the weight of trapped water damage things like windshields and stanchions, but enough water can put too much stress on a boat’s keel or jack stands and cause structural damage. For a sailboat, it’s often easy to run taut lines from the boom and mast to stanchions to make a strong support. Powerboats typically need some type of wooden framing to give support.
Shrink-wrap should only be installed by someone who is familiar with the process. LDPE is shrunk using heat, typically from a propane-fired heat gun. Getting the gun too close to the material can cause it to melt and drip onto the boat, which is difficult to remove. And since fiberglass and wooden boats are flammable, it’s easy to see how a moment’s carelessness can lead to disaster. The boat above was being shrink-wrapped by its owner when something caught fire. LDPE burns slowly. Chances are, a piece of shrink-wrap ignited and fell on the boat’s helm seat, igniting it. Once the owner spotted smoke coming from inside the boat, it was too late. Though the fire department responded within five minutes, the boat was engulfed when they arrived and wad destroyed -- but not before destroying 29 more boats, and damaging another 70. The fire investigator noted that this was the first time to owner had shrink-wrapped his boat. He also suggested that having a fire extinguisher on hand may have prevented the fire.
Anyone who plans to do their own shrink-wrapping would be wise to work with someone who has done if before. Better yet, leave it to the pros. Paying for installation might be a lot cheaper than you think.
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