Adding Insulation to Wind Horse


One of the projects on our list to be done before heading back to cold water is adding a bit of insulation on the bottom of the hull in the forward and aft sleeping cabins. The normal practice with polyurethane foam is to stop it above the waterline. With our Armaflex being relatively hydrophobic, this precaution was not necessary. However, due to a miscommunication between us and the builder, the Armaflex stopped about a foot (30cm) higher than we wanted, as you can see in the photo above. As a result, last summer in Alaska we had a small amount of sweating on the bare metal in the forward and aft sleeping cabins.

A few weeks ago we ordered a roll of Armaflex from a local supplier, and had them slice this into appropriate widths to use on the hull, frame webs, and frame caps.


The sliced material was then cut to fit.


The Armaflex has an adhesive backing. Peel the protective paper to expose the adhesive, and then push it onto the surface.


Here is what the area in the first photo now looks like. There is a slight difference in the finished surface. The original Armaflex was made to order for us and has an extra protective coating on it.

This same approach will work if you have a fiberglass hull with a sweating problem. It also helps to deaden sound – something that is really helpful in most fiberglass boats. Armaflex is available from industrial rubber suppliers and also air conditioning supply houses (the air conditioning industry often uses Armaflex in air ducts).

Posted by Steve Dashew  (April 21, 2007)

3 Responses to “Adding Insulation to Wind Horse”

  1. Insulation ... - SailNet Community Says:

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  2. Nathan Pincher Says:

    Hi Steve,

    We have a 40ft steel motorsailer currently being rebuilt and I found your comments on various websites regarding Armaflex. How’s it holding up for you? Everyone at our boat yard has said we need to use spray-on foam but having just removed 100+ garbage bags of old, mouldy, mildewy, water soaked foam from our boat, I’m not convinced.

    I’m emailed Armaflex to understand whether Class O is the same as Class AP – otherwise, I’d be keen to hear from you how you’ve found the product to be.

    S/V Bellissima.

  3. Steve Dashew Says:

    The Armaflex works great. Using it on the FPB 64s as well as Wind Horse.