Test Compares Insulation Below Waterline


The following is the test protocol for our report on cost-effective insulation for boats.

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
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at darrellnicholson.com.