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Old 09-01-2012, 18:10   #1
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Hull Insulation for Tropics

Hi everyone! I am trying to develop a spec for a new build of a semi custom 64 ft to be cruised in se asia and pacific. I am pretty set on navy blue hull for esthetical reasons, but am concerned it will make her boiling hot down below. Have decided against teak decks to keep her white at least up top for same reason. But am also thinking good hull and cabintop insulation may help. Looking for advise re: a) armaflex vs other insulation types - any direct experience? B) what would be the appropriate insulation thickness? Thanks in advance, GK
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Old 09-01-2012, 18:27   #2
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Re: Hull insulation for tropics

As an engineer with experience in insulation I can point out some things you should keep in mind.

Moisture and mold are you big enemies on a boat, especially in the tropics. If you use any loose insulation or especially loose, closed cell material like foam plastic or rubber you risk trapping moist air between the hull and the insulation such that when conditions are just right there will be condensation trapped in the space. This can damage or infiltrate your deck structure or at least turn into a black mold slime. This obviousely presents a problem. My gut feel is that a bonded, closed cell insulation stuck intimately to the interior of the fiberglass might be OK. You can buy high end Peel & Stick closed cell rubber foam or perhaps a foam in place material might work. Be sure you stay away from embedded metal stuff like chain plates. If you need to pull wires in the future place enclosed runways first.

I'd like to hear from folks with first hand expeience on this. It might just be that a foam core deck is well enough insulated alone that there is not much to gain ralative to the ventillation you will have anyway. The risk of damage may outweigh the bennefits. At the very least, insulation makes it difficult to inspect from the inside. We will be moving our boat to the tropics too. Good plan on the white decks.
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Old 09-01-2012, 18:31   #3
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Re: Hull insulation for tropics

Paint everything as close to white as your aesthetics will allow. Might want to put some insulation in the deck though the core seemed to be fine for our boat under sail. When at anchor, we always put up an awning which took care of solar gain and kept the boat comfortable both above and below deck. I'd be more concerned with insulation If I was going into 'temperate' areas.

Was on an uninsulated boat with a broad dark blue stripe down the hull side. From the inside, you could feel the solar gain where the blue stripe was.
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Old 09-01-2012, 18:43   #4
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Re: Hull insulation for tropics

Agree on the awning. I forgot there is a canvas Tropial cover in our inventory made to cover bow to stern. Ptobably one of the best options.
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Old 09-01-2012, 19:11   #5
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Re: Hull insulation for tropics

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Originally Posted by gkrasnov View Post
Hi everyone! I am trying to develop a spec for a new build of a semi custom 64 ft to be cruised in se asia and pacific. I am pretty set on navy blue hull for esthetical reasons, but am concerned it will make her boiling hot down below. Have decided against teak decks to keep her white at least up top for same reason. But am also thinking good hull and cabintop insulation may help. Looking for advise re: a) armaflex vs other insulation types - any direct experience? B) what would be the appropriate insulation thickness? Thanks in advance, GK
Was on a newly built aussie cruising crusing catamaran in a marina on the gold coast between 11am and 1.30pm the hottest part of day. All foam construction with bluish hull and white topsides and antislip on decks, saloon and full cockpit hardtop in off white/cream color. Vessel design had terrific flow through ventilation that suggest could live aboard easily without AC. The design with full hardtop canopy seemed to pull the air through.


Could walk on decks no problems at all barefoot whilst was an issue on timber of the pontoons.

There is foam of 30mm and up to 40mm in build and I think the saloon, deck and full hardtop would be using those laminates.

A big liveaboard 46ft the vessel is still light ( 7.44T - 800kg (liquids) = 6.64T Lightship - app 300kg anchor gear) and will be a performer
.
Seems it can be easily done with design and right materials.
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Old 10-01-2012, 09:14   #6
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Re: Hull insulation for tropics

Thanks guys, that's really helpful!!! Havn't thought about the potential mold damage. Sounds like just deck insulation, good ventilation and awnings might do it. Sheesh, that's a lot of money saved...
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Old 10-01-2012, 13:42   #7
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Re: Hull insulation for tropics

We sailed the tropics in a boat with BLACK topsides and I did not notice any ah-so heat. Alas, our topsides are very low hence the area exposed to the sun is not all that great. Also, when we open the front hatch and remove the washboards the boat becomes one drafty corridor.

The topsides are vertical, or, in some cases inverse, which seriously reduces the amt of heat induced.

The decks are a different story as they are exposed to hours of nearly head on radiation. On the one hand, a teak deck is an insulation per se, on the other hand, teak is relatively dark, and will heat up. I think I would go for very light cream decks and superstructure in grp. White, especially off-white is no good at all since it tends to reflect the light so much that one has to wear grade X dark shades all day long.

So, my 2 cents is, stick to your dream navy blue topsides and insulate the topsides from the inside (or build a sandwich boat from the water level up). Go for light, but not off-white, sandwich decks, and light color canvas.

BTW you may opt to design-in plenty of opening hatches that open both ways so that you can induce plenty of draft while at anchor. Alternatively, shut everything up, and turn on the aircon.

Cheers,
b.
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Old 10-01-2012, 13:59   #8
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We have an aluminium hull which have a history of being hot in the tropics. We have 50mm closed cell insulation. But the real winner for keeping the heat out for us is total coverage with canvas and great ventilation, our canvas has drop panels on the side as well keeping out the morning and evening sun as well. We used the smoke from a stick of incense to figure out the optimum combination of hatches to create airflow and since we live off the hook mostly we find life very comfortable even near the equated.
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Old 10-01-2012, 15:00   #9
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Re: Hull insulation for tropics

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Originally Posted by Nicholson58 View Post
As an engineer with experience in insulation I can point out some things you should keep in mind.

Moisture and mold are you big enemies on a boat, especially in the tropics. If you use any loose insulation or especially loose, closed cell material like foam plastic or rubber you risk trapping moist air between the hull and the insulation such that when conditions are just right there will be condensation trapped in the space. This can damage or infiltrate your deck structure or at least turn into a black mold slime. This obviousely presents a problem. My gut feel is that a bonded, closed cell insulation stuck intimately to the interior of the fiberglass might be OK. You can buy high end Peel & Stick closed cell rubber foam or perhaps a foam in place material might work. Be sure you stay away from embedded metal stuff like chain plates. If you need to pull wires in the future place enclosed runways first.

I'd like to hear from folks with first hand expeience on this. It might just be that a foam core deck is well enough insulated alone that there is not much to gain ralative to the ventillation you will have anyway. The risk of damage may outweigh the bennefits. At the very least, insulation makes it difficult to inspect from the inside. We will be moving our boat to the tropics too. Good plan on the white decks.
My thoughts exactly! I use to have a flag blue hull which is foam cored but still could feel the heat next to the inside of the hull on a hot sunny day (PNW). I painted it yellow last year and it did make a difference.

Also the boat use to have styrofoam under the headliner. When I pulled it out to do the rebuild there was mold under it.

So yeah! I would go with the best foam coring rather then insulation for wet climates. And in your cabinets allow for some air passage, especially for clothes.

There were times in the Philippines (Nov - Feb) that the walls in my in-laws house would sweat. Everything was wet even the clothes you were wearing. A wool blanket was my friend at night.
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