Insulating a fiberglass hull

[RyanN]

Has anyone retrofitted insulation to a FRP hull?

After living aboard for a cold North Carolina winter, I'd like to insulate my hull before moving the family back aboard.
We have several areas where large portions of the inside of the hull are exposed (painted). The condensation was awful. Most of the paint on inside of the hull which had been perfect for 20+ years failed. The lockers were damp, and the temperature inside ranged from 70 at our heads to 40 at our feet.

My thoughts were to to glue marine vinyl with contact cement to panels of Elastomeric insulation such as this from Grainger. This is the stuff that most pipe insulation is made of. These panels would then be glued to the bare fiberglass inside of the hull. This should give almost R4 which is better than nothing.

In the head (at the bow) I was going to glue strips of foam (corecell or perhaps cheap PU) to the hull and glass over. I've never had a problem with oil canning but some extra stiffness can't hurt.

Should I insulate below the cabin sole? should I insulate the bottom of the cabin sole?

Anyone been here before?

Thanks

 

[Fanie]

Hi Ryan,
If you are going to do the insulation, you can just as well add some flotation. I would think that some of the foams one get nowadays could make a nice difference. Very well in heat / cold isolation and can do as well in flotation.

 

[StianM]

I would also be interested in this since I'm planing a boat for all year use.

I'm not sure if applying anything directly to the hull would be the way to go since it's where ale the water will condense. I think I would rather insulate the panels in the boat itself.

 

[Fanie]

Condensation takes place when high humidity comes in contact with a colder surface. If the foam is neutral in temperature, there should be no or very little condensation.

 

[StianM]

If the foam is neutral in temperature, there should be no or very little condensation.

I don't like the word if and not he word should ether

We use some nice insulated panels at work for the interior. I will see if I could get some of them with me home if they damage some of them and they are refused by the customer.

It's 2x 1mm painted steel plates with a 4cm layer of stone wool between.

I think insulating the hull should only be done a-bow the waterline. The water has the highest heat capacity and are in most cases colder then the surrounding air so the condensing should happen mostly there.
Talking out of a totally theoretical point here.

 

[Landlubber]

Steel boats are usually only insulated above the waterlive to control condensation.

 

[Northman]

Stian,
who is manufacturing these panels? Is it a Norwegian product (I am in Norway too)?
Another option would be a rockwool product which is covered with GRP on one side - see http://guiden.rockwool.no/produkter/passiv-brannsikring/conlit-150 (in Norwegian only, but you should be able to find the product number at your local dealer). You would have to seal the overlap, though.

Walter

I don't like the word if and not he word should ether

We use some nice insulated panels at work for the interior. I will see if I could get some of them with me home if they damage some of them and they are refused by the customer.

It's 2x 1mm painted steel plates with a 4cm layer of stone wool between.

I think insulating the hull should only be done a-bow the waterline. The water has the highest heat capacity and are in most cases colder then the surrounding air so the condensing should happen mostly there.
Talking out of a totally theoretical point here.

 

[Herman]

Insulate with whatever foam or material you can get. Boats are wet, so fibrous materials are not a smart idea. PU foam has a good insulation value, just do not bother with stiffness.

2K PU is available as sprayable compounds in ready-to go compressed cannisters, hose and spray gun. That should work well, above the waterline. Below the waterline / floor I would not bother. You do not want bilge water to be able to soak the foam 24/7. Get a bilge pump in there which pumps away the water / condensation.

 

[Kaptin-Jer]

Any solid foam will give an R rating. The rating will depend on the thickness of the foam. A 1" to 1 1/2" foam panel will give about R4.5 which is about what you will have on the furred wall of a CMU constructed house. 3" will give about R11 which is what you will find in the roof of a commercial building. It depends how much headroom you want to give up. A 1.5" foam panel glued to the top of the salon should give you a measurable difference in temperature. I use it, but for keeping out the heat not the cold.

 

[apex1]

Use "Armaflex" go several inches below waterline or straight down to bilge! Do not use the "el cheapo" foamstuff it will suck moisture after a while and feed mold and mildew!
look:
http://www.armacell.com/
for tec. info
and:
http://www.setsail.com/dashew/hull_insulation.html
to see how some experienced sailors do it!
Northman and the other vikings: do not use rockwool and the like!!! It´s a sponge !
Do not waste your money, do it right.
Regards
Richard

 

[Northman]

To Apex1: The idea is to seal the insulation (e.g. Rockwool ) behind a water- and airtight barrier. Haven't done it myself, but found the idea at a German designer - se http://www.al-yachtdesign.de/helgnlos.htm. For all I care, the man is way too much convinced of his own supremacy in everything to do with boatbuilding, but some of his ideas are still appealling. In terms of insulating a steel hull, he calls it standard practice on coolerfreighters which obviously are insulated with Rockwool or the like and sealed behind an Alu-foil. I have talked to to a guy who has done his yacht that way and it seems to work.
Of course, Rockwool or any other fibrous material which is not sealed, would be soaked in no time, just as Herman pointed out.
Walter

 

[Fanie]

Rockwool is superior to ie similar fiberglass insulation. Rockwool is good if you use it in high temperature insulation applications and will uphold to around 800 deg C where fiberglass begins to disintigrate at around 230 deg C.

However, if you are looking for a good heat insulation, as well as booyancy properties, then nothing beats the PE foams. Although pricey, I won't use anything else. It doesn't absorb water, it does not rot or allow algea to grow on it. I have offcuts lying outside in the sun (and ours is harsh) and exposed to the elements for more than 5 years, and it looks like the day I got it. Ok you have to brush some dirt off, but other than that it is as new.

You can cover it with vinyl, PVC canvas or glass over it, whatever you like. James Bond glue glues it very well. It does not gather mildew either unless you wet it physically.

Temperature wise it is dead. It conduct heat (or lose heat) very slowly so for temperture insulating I would consider it strongly. Compared to Rockwool, I would not even consider rockwool unless it's for insulating the stove or something radical.

Heating the PE foam with a heat gun on the one side to the point where it surface melts the reverse side is still cool to the touch. The side you heat up expands and bulges which is understandable due to the closed cells air expanding severely. Thickness ~ 30mm.

In this case the temperature difference is radical. The same however applies to very cold one side and room temperatuer the other. Properly insulated I would estimate that one's own body heat could keep a relative area comfortable providing there is no drafts or leaks of course.

Note this is PE foam I'm referring to, and not PU foam.

 

[apex1]

To Apex1: The idea is to seal the insulation (e.g. Rockwool ) behind a water- and airtight barrier. Haven't done it myself, but found the idea at a German designer - se http://www.al-yachtdesign.de/helgnlos.htm. For all I care, the man is way too much convinced of his own supremacy in everything to do with boatbuilding, but some of his ideas are still appealling. In terms of insulating a steel hull, he calls it standard practice on coolerfreighters which obviously are insulated with Rockwool or the like and sealed behind an Alu-foil. I have talked to to a guy who has done his yacht that way and it seems to work.
Of course, Rockwool or any other fibrous material which is not sealed, would be soaked in no time, just as Herman pointed out.
Walter

I understand, but I´m in doubt the sealing will be tight, except you go for some serious effort (cost).
Herr Luft the German "Designer" has a brother at this forum (at least a kindred spirit). Both of them own the only recipe of baking bread! And they harp on about their brilliant way of boatbuilding and are so cinvinced of their own genius, I would not take their advice for free! Except for baking bred maybe.
Why adding weight, labour and unforseen trouble by using lousy stuff? Armaflex does the job. ...unfortunately I´ll get no commission........
And take care, not only fibrous material gets soaked, every sort of PU foam does!
Regards
Richard

 

[Northman]

Richard,
I absolutely agree with you on that a great deal of care would be in order when looking at a lot of Herr Lufts "recipies of baking bread" as you put it. Still, burried among all the self-inflated egotrips I also found some good ideas.
When it comes to insulation: Armaflex sounds nice, the price doesn't. That's why I am still looking for a less expensive solution.
And no worries, I don't suspect you of getting commission for anything ... Enjoying your input!
Walter

 

[apex1]

Richard,
I absolutely agree with you on that a great deal of care would be in order when looking at a lot of Herr Lufts "recipies of baking bread" as you put it. Still, burried among all the self-inflated egotrips I also found some good ideas.
When it comes to insulation: Armaflex sounds nice, the price doesn't. That's why I am still looking for a less expensive solution.
And no worries, I don't suspect you of getting commission for anything ... Enjoying your input!
Walter

Thanks for your kind reply. Yes even those egomaniacs sometimes publish good ideas, one must be able to sort them out.
Back to topic: if you buy other foam than PU,the mentioned "corecell" read dyvinicell, nidacore and the like, you spend easily 5 to ten times the amount then for Armaflex. But you still do´nt have the heat resistance of Arma. I agree, the stuff is expensive, but worth the money.
just my € 0,02
Regards
Richard