Test Compares Insulation Below Waterline


First, we set up an R-value test rig, exposing sample materials to a temperature difference and measuring the difference in heat flow (see adjacent photo). The main thing to take away from this is that small areas of very poor insulation-windows or non-cored laminate-will benefit best from insulation.

We then tested a variety of materials on the hull and air conditioning ducts for both surface sweating and condensation underneath. We placed 10-inch squares of a variety of materials against a non-cored FRP hull resting in 34-45 F water for several months. Some we sealed to the hull with tape, some were simply pressed against the hull, and some were self-adhesive.

Although this is not a live-aboard boat, we did make a point of spending at least one night per week on the boat. We turned the dehumidifier off and closed all ventilation. The relative humidity hovered between 55-65 percent, and the temperature ranged from ambient to 72F.

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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