DIY Mast Boot

Four simple ways to waterproof the mast-deck connection.


With a little imagination and some inexpensive materials, you can put together a leakproof mast boot in a few hours.

leakproof mast boot

1 Roofing Rubber

One reliable boot sealer is self-adhesive ethylene propylene diene monomer (EPDM), a common rubber-membrane roofing material. Sold at local building supply stores, the rubber is black in color and comes in a roll that is 5 inches wide. (Dont confuse it with ice and water shield, which is much thinner.) Peeling the plastic backing from the underside of the EPDM material exposes the sticky side. Arrange precut strips prior to permanent installation. We suggest using American-made products as the imported stuff doesn’t adhere well to itself.

2 EPDM + plastic sheeting

A white, heavy, PVC plastic sheet can be installed over the EPDM for cosmetics and additional protection, or you can use it by itself. You can seal all of the overlapping seams at the mast with a medium-strength adhesive caulk like 3M 4000 UV. You also can seal any material held in place with hose clamps with butyl caulk (easier for disassembly later). Some cruisers have successfully installed only the plastic sheet as a mast boot.

3 Bandage Boot

Surprisingly, a common Ace bandage can be used to make a mast boot. Simply wrap the bandage around the mast, starting at the bottom and going up to 6 inches above the deck. Apply a thin coat of Hypalon paint (commonly used to waterproof RV roofs; Geocel is a common brand) to waterproof the bandage. To further protect the Hypalon from the suns ultraviolet (UV) rays, it might be worth applying a coat of exterior acrylic house paint, which will expand and contract and has better UV properties than an oil-based paint. (The mast boot pictured has lasted over four years without a leak.)

4 Truck tire tube

You can cut up an old truck-tire inner tube and wrap it around the mast, sealing the contact edges with butyl sealant. Seal the top with self-bonding rigging tape and secure the bottom with heavy monofilament fishing line. Seal the overlapping tube with contact cement or an adhesive sealant.

If you decide to go the retail route, there are very nice-looking, factory-made, contoured mast boots. But be sure to seal the area that joins the mast, under the retaining clamp, with butyl caulk rather than silicone. Butyl is far easier to remove with mineral spirits where silicone will need to be cut, scraped, and sanded from the mast. Where the mast boot overlaps, seal the seams with contact cement or an adhesive sealant.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


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