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Old 05-15-2013, 12:13 PM   #1
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how to insulate a fiberglass hull for warmth and condensation

I'd like to find a product to insulate the fiberglass hull of my boat to stop the condensation problems I'm having and to contain more of the heat.
What I'm thinking of doing is applying some kind of closed cell foam like neoprene or maybe better yet cross-linked polyethylene to the inside of the hull with contact cement. The cross-linked polyethylene (XLPE) comes in 2 lb. and 3 lb. density, 3lb. has a blend of EVA and poly, and is anti bacterial, and passes FMVSS-302 flame retarding test. These specs are going a little over my head. Some of the insulation would be exposed and would need to be a light color.
Anyone have any experience with insulating a hull like what I purpose to do. I'm in SE Alaska and it's wet and cold here, and life would be better with insulation. Thanks all for your input.

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Old 05-15-2013, 02:04 PM   #2
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I like the Shuckers'. Serious cruisers.

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Old 05-15-2013, 04:57 PM   #3
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Love the Shucker too, have a friend with one.

Fredrick Mate's book From a Bare Hull has a good, albeit a little old section on insulating a bare hull b/4 interior finishing.
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Old 05-16-2013, 05:27 AM   #4
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Far easier to simply add more dry heat.

Many foam insulation burn very well so needs fire proof covering , a hard refit.

Also insulation works by the inch so 3 inches will be more effective than 3/8 stuck on the cabin sides or overhead.

Double insulate the glass area , and see if you can switch to a hot plate to cook , instead of propane.

The easy solution is MORE HEAT!.
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Old 05-25-2013, 06:39 PM   #5
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you can try building up layers of cork, easy to work with, very flexible, almost impossible to light up, high insulation factor, noise reducing, mold preventing, "green"...6mm cork rolls can be found in most carpet shops.
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Old 05-26-2013, 04:33 PM   #6
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We cut 4X8' sheets of two inch pink foam board insulation into 2" strips and lined the entire hull (engine room excepted with it. The 2" strips made it easy to conformable to the hull shape. We ran some vertical beads of caulking and pressed it in place like planking, then sealed the edges.

This works very well if you seal it so that no air gets between the foam and the hull. 16yrs living aboard in Toronto has taught me a few things.
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Old 05-27-2013, 02:10 AM   #7
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Ok I keep our boat in Seward AK

If you are getting condensation under your bunks then 1" foam insulation will do the trick.

If you are getting it anywhere else then plain and simple you need to add ventilation.

Well ventilated boats do not have condensation problems.
Kevin Sanders
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Seward, Alaska
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Old 05-27-2013, 09:55 AM   #8
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Condensation is moisture to retain heat is insulation but more dry heat will reduce condensation and keep the boat warm and dry. We insulated the boat indirectly by adding cabinets, selves drawer curtains on the out hull walls. In the salon and state rooms the outer walls have something covering them, so there is sort of a dead space between the hull and interior living area.

We also watch the amount of moisture we create, air out the boat, circulate the air and have dry easily pots. however the best is the 100,000 btu diesel heat. The plex a glass over the salon windows help also.
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Old 10-23-2013, 01:32 PM   #9
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As I am getting ready for my first winter aboard I find my "Engineer" career getting in the way a bit, lol.
What causes the most heat lost ? Conduction thru surfaces (hull, bulkheads and windows) or convection thru drafts of poorly sealed openings ?

Each method will be addressed differently. For example: Foam panels, carpets and batts of insulation against the hull will address conductivity.
Drafts can be minimized with shrink wrap, tapes, door seals etc....

I am thinking that reducing the conductivity thru hulls and windows will reduce loss the best because drafts are actually good for ventilation and they can be easily controlled as needed.
I have a propane fireplace, a diesel fireplace and electric heaters as heat sources.
1982 41' President
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Old 10-23-2013, 02:05 PM   #10
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While drafts are good for ventilation...I think they can be a much higher source of heat loss and maybe more importantly just discomfort.

on my boat...the amount of window area is so great...much additional insulation to walls is probably lost effort unless I do something to them also.

my 2 doors have pretty major drafts associated with them...just stuffing the tubular foam pipe wrap in them at night or when the winds howl makes a huge difference.
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Old 10-23-2013, 02:37 PM   #11
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Take a look at this web site: Advanced Coating Solutions | Energy Saving Solutions for Industrial and Marine Customers

I have used a product they sell called Mascoat on the interior of a fiberglass boat and it worked extremely well in reducing condensation. Because it can be painted on, it can be used in places where foam and carpet are not alternatives.


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