Best Hull Insulation

[Sue & Larry]

I live in Alaska and I need to insulate the inside of my fiberglass sailboat. What is the best thing to use?

Sue & Larry respond:
Breathing, cooking, and general body heat cause can cause condensation inside the hull of your boat when sailing in cold climates. Heat, ventilation, and insulation are the remedies to the problems that condensation can cause.

Our boat, Serengeti, used to be in Alaska and Seattle. It's insulated with half-inch, flexible, closed-cell foam glued against the inside of the hull. This is the most popular way to insulate boats and reduce condensation problems. It's especially important to cover the areas of living space down to the waterline. Choose closed-cell foam as it provides a higher R-value than other types of foam; in addition, it doesn't suck up moisture.

We know some sailors who report success with using indoor/outdoor carpeting as insulation against the hull. Moreover, others use the foil covered bubble wrap or foil covered flexible sheets of foam. If you choose a foil covered material, always face the foil towards the inside of your boat.

When insulating don't forget to cover any metal through-deck fasteners, as these will literally drip water as condensation occurs on them. For other ideas, you might want to check out the article on Wintering Aboard by Mark Matthews.