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Cabin Insulation?

4K views 23 replies 12 participants last post by  chrisncate 
#1 ·
I have been insulating the boat for the winter to reduce hull sweating. Last year I didn't and it was nuts how much heat escaped and the amount of sweating of the hull. The Mid Atlantic/Chesapeake Bay experienced one of the coldest winters on record last year.

Unlike the engine area insulation where I used Soundown, with lead core... its too heavy and expensive to even consider. I am trying some 1" Styrofoam board with foil barrier on one side, plastic on the other from a home improvement store. Then taped all the seams.

I did not glue it to the hull, rather I tried to leave a air gap where I could, hoping this separates the two temps and does not cause any mold. I will check it in the Spring to see.

Some other places I cant reach I was thinking expanding foam?

Thoughts on insulating a boat for weather?

-------------------

FWIW, I am disappointed boat builders, designers, etc do not consider insulating boats more? Not just for winter, but summer heat as well, and sound deadening.

Are there any boats that are built with proper insulation?
 
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#2 ·
Shawn,

If you don't mind a recycled response I wrote recently on another forum, I will include a portion regarding insulation below:

Insulation helps, but only if it is adequate and sealed so moist air cannot get between it and the cool surface it is insulating... [Adequate defined as thick enough to keep the heated side of the insulation above the dew point in the cabin. 1" foam board or closed cell foam used for HVAC ducts are both adequate here. Those with radiant foil surface on the heated side are a plus. I often use two 1/2" foam boards, installing the first foil side out against the hull (for future insulation in the tropics) and the second on top of the first foil side in. This provides greater flexibility for fitting tight curves.]
If you wish to read the entire post in context with additional hints on keep a boat dry during cold weather, please see my blog post at:

svdenalirosenc43.blogspot.com/2015/11/living-on-boat-in-winter.html

In hopes you are warm and cozy.

Cheers!

Bill
 
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#8 ·
Shawn,

If you don't mind a recycled response I wrote recently on another forum, I will include a portion regarding insulation below:

If you wish to read the entire post in context with additional hints on keep a boat dry during cold weather, please see my blog post at:

svdenalirosenc43.blogspot.com/2015/11/living-on-boat-in-winter.html

In hopes you are warm and cozy.

Cheers!

Bill
What do you use on the foam to adhere it to the boat?
 
#4 ·
Shawn, I never have a problem with hull sweating while the boat is on the hard. However, I have a fair amount of air flowing freely through the boat at all times, which I guess prevents this from happening. I have a solar exhaust fan in the head that runs constantly, day and night, plus a 6"X6" louvered vent in the main hatch cover. Additionally, my hatch over the Vee berth was a replacement that never fit tight, therefore it leaks lots of air, but has a screen to keep the critters out of the boat. The only time I have a mildew problem is during mid summer, when we've had a lot of rain and the boat has been closed up for a couple weeks. I wipe this down with bleachwater and Dawn dish detergent, which does a great job.

All the best,

Gary :cool:
 
#9 · (Edited)
Do you live aboard ,full time, including cooking aboard , right thru the winter?
Ventilation was useless for me, on my first boat. Styrofoam sheet had major condensation behind it, despite my best efforts at a vapour barrier.
1 1/2 inch of spray foam right down to the floor boards, did the trick. Nothing else worked.
Now my boat is the most comfortable home I have ever lived in . If yours is not, then you are doing something wrong.
 
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#5 ·
I assuming that T37 is in the water year around. No, you won't sweat on the hard because the hull and air are the same temperature. Obvious.

The reason for the hull sweating is that the water is cool and the air is warmer, either because of the current unseasonable weather (that prompted the post--with cold water and warm air boats and rocks sweat non-stop) or because you are living aboard and creating moisture (breathing, cooking). The cure is not ventilation--that can actually make it worse in many case by bringing in more moisture--but making sure the humid air cannot contact a surface that is below its dew point. In this case, if there is ANY air leakage behind the insulation, it will condense and there will be mold. Houses are different. They leak a little through the siding and the outside air is very dry in the winter.

The best answer is a cored hull (nice and thick), but that presents problems below the waterline. Failing that, the insulation must be bonded tight to the hull and not permeable. The other answer is to keep the humidity very low (40-50%) by running a small dehumidifier; doesn't take much if the boat is tight and leak-free.

If I were designing a boat for real use in cold climates I might consider adding a laminated foam core inside the all-frp hull (the core would only be for insulation), fitted well clear of all through hull fittings. Nice and warm.
 
#6 ·
The foam board would work, IF, as pdq says, you can ensure there is no air flowing behind it. Otherwise you will get condensate and nasty problems. If you install closed-cell padding, like sleeping bag or yoga pads, from heavy ensolite or other closed-cell foams, and you bond them 100% with a good glue, you eliminate any chance of a condensate problem. Of course, that's a "forever" installation, or a huge chore to remove. And that stuff isn't cheap, no matter how you do it.

You may want to try that, at least in some smaller area like the forepeak or in a closet that has one side against the hull, for comparison. the different closed-cell foams all can be scuffed or plucked or abraded, so you'd also want to consider placing a vinyl wall-covering or sheet stock of some kind over that, for long-term protection.

In theory you could also use the mylar-faced "bubble wrap" type of insulation that's also sold for home use. That's relatively inexpensive, but nowhere near as effective because the air does circulate within each bubble and as such it insulates less. But it can be a fast way to add temporary insulation to an area, to see what difference it will make, in what thickness. Also good temporarily over hatches & ports, if you use the clear stuff, as it will still let light in.
 
#10 ·
Brent, when I lived aboard it was in the Florida Keys - no problems with sweating hull there, but when things got a bit damp I fired up the AC and it dried out the entire boat in less than 30 minutes. To me, it would be insane to live aboard a sailboat in Chesapeake Bay, or anyplace north of Miami, year round. That's why I bought a sailboat. I can go to locations where the temperature and my age are equal, which is the way I like it.

All the best,

Gary :cool:
 
#15 ·
Yes , I have used the option of going south, many times , but have always been glad to get home again. I find that properly insulated and with a good wood stove , my boat is the most comfortable home I have ever had . Clients who have lived ashore for many years, say the same. It would be insane to spend the cost of living in a house, and going to work every day to pay for it, when living aboard let me semi retire in my mid 20s, working a month a year since then.
Given the bureaucratic hassles of living aboard in Florida , one would be insane to try live aboard there, when freer options are available.
People who haven't figured out how to live comfortably aboard in a cold clime, are poor source of info on how to do it.
 
#11 · (Edited)
YES... I am living aboard year round in the water (Yes Gary I must be insane but I also have children and cant just pick and leave when the temp drops below 70... but you can so enjoy) I did get a dehumidifier this year, all the are cowl vents/dorades are sealed and solar vents off and closed.

I was told a air gap was good? But what you all say about glue it tight makes sense now because the hull does not breath unlike siding on a house.

Thanks for ideas... seems I am not far off from what is proper. :)
 
#17 ·
Here in BC, the ocean doesn't get all that cold, and during below zero cold snaps , being in the ocean keeps things from freezing. I spend a lot of time in drying anchorages ,but when the cold snap comes I head into deep water, to keep things from freezing (especially canning jars in the bilge).
 
#13 ·
Thoughts on insulating a boat for weather?
You are trying to accomplish two things: keep the heat (cool in summer) inside the boat and avoid having exposed surfaces fall below the dew point (which leads to condensation aka sweating).

The best way to accomplish most of both goals is to insulate the hull during construction. On my boat the deck and hull to the waterline are insulated internally. The Swedes understand cold weather.

Oh - staying in the water helps tremendously. The water, even when iced over, is warmer than the air. A winter on the hard is a very cold and unpleasant place.

The reason people have problems with glued on insulation is that there are gaps in the adhesive where moisture laden air (often from the surrounding adhesive) lead to anaerobic molds and mildews growing. You can deal with that by careful application of adhesive, as you would when putting up wallpaper, or vacuum bagging. Both are a lot of work and should be considered permanent. An aesthetically pleasing installation can be achieved with finished battons.

Remember you have to get inside the lockers also or they will turn into water baths. You will lose storage space.

I'm not a fan of expanding foam. It is too hard to control.

High efficiency thermal paths through the hull are a problem - ports, hatches, jib track mounting bolts, chainplates, and keel stepped masts. Ports and hatches are most easily managed with several layers of bubble wrap on the outside of the boat. You can put a couple of layers of bubble wrap over the jib track also. I haven't come up with or heard of a solution for masts; you are likely to have some level of condensation on the mast.

Part of the solution is keeping the boat warm. The warmer the boat the "less cold" the cold spots are likely to be and the more often you will keep the exposed surfaces above the dew point.

Ventilation is key. In winter the outside air is very dry (low absolute humidity). Sources of humidity in the boat are simple: breathing, showers, combustion, and evaporation. Stopping breathing is really hard. Showers ashore are a nice solution most of the time. Combustion (cooking, some older propane and diesel bulkhead heaters) is hard to avoid if you cook for yourself; ventilation is key. Evaporation is the biggest issue during cooking (more roasting and broiling and less boiling and saute).
 
#16 ·
I have had my boat dripping wet inside, and an hour of running the wood stove has dried it out completely. It takes only 2 degrees of difference between air temperature and the temperature of a surface for condensation to form. Thus, the only way ventilation can eliminate condensation is to have enough ventilation to keep the inside temperature the same as outside!
SOME SOLUTION!
Friends who have used the spray foam kits, which look like a couple of propane bottles you hook up to a nozzle, say they are easy to use, and not all that expensive.
I believe they have a goop you put in a caulking gun, which bonds, but doesn't dissolve styrofoam. I may remember wrong , but it may be called PL200. It may be thick enough to make sealing the edges easy.
 
#19 ·
Don't know if it'd even be an option to consider, but on our boat the woodstove really stopped the condensation. Before we installed it it would sweat badly, after (and of course only when we fired up the woodstove) the entire boat was bone dry on the coldest dampest days. The stove sucked the moisture right out.
 
#20 ·
I am a fan of woodstoves as well and there are a number of choices now other than the expensive (though lovely) Navigator. I don't have my file with me but there is one English manufacturere being reped in the states and two domestic producers...the old Shipmate woodburners once again available and one called "The Cube". The Navigator Sardine would be perfect for my 28 but my to get list is a bit long so I will have to get something easier on the wallet. I knew someonf who got one of the little pot-belly cabin stoves at a junktique shop for $120.00 and it worked out very well.

Cork might be an interesting insulation option and is available in many forms these days including as curtain backing. It is attractive as well as antimicrobial (resistant to mold) and can be fairly reasonable in cost.
 
#21 ·
Let's all remember that the only magic of a wood stove (as compared to other heat source) is that wood stoves are designed to run with more air up the flue to prevent any risk of smoke in the cabin. Put simply, ANY heat source will do the same if you waste enough heat through additional ventilation. Electric, oil, or gas. True of most home woods stoves too.

Some gas heaters have a bad reputation because they have very small flues to increase efficiency (Cozy cabin is 1"). Because they don't smoke, they can kinna get away with it (except you get wet). If you ran a wood stove on a 1" flue you wouldn't be able to see across the cabin. A gas heater with sealed combustion is just as dry as any other type.
 
#22 ·
No magic, just good DRY heat (much welcomed after a long wet run in from the Pacific) as opposed to propane or kero. Diesel and electric are also dry but smelly and impractical on a sailboat.
The "magic", which is of great value to me and others are the aesthetics of a wood fire.
I know a few wooden boat owners who see a wood stove as a valuable tool in keeping the interior of there boats dry and so a help in combating rot.
 
#23 ·
But to be clear, it aint' the wood heat, it's the ventilation. That's the simple physics.

AFWIW, wood heat is banned in some marinas, because of smell and because of ash fall-out. Drop ash on the wrong boat and you'll be hating life. I've overheard the wrath.
 
#24 ·
Wood heat is a dry heat. Other heat sources may or may not be dry heat. Propane certainly isn't dry. Worth noting is that wood stoves are designed to utilize the stove housing as radiant heat. Other heat sources might not do that, and instead use an element with a fan or some other method. The dryness of burning wood mixed with the large dry surface area of the stove itself make for a great heat source on a wet damp boat. Probably the best for simplicity, cost and effectiveness.

Wood heat is one of the driest sources of heat. Yes, largely due to the dryness of the heat coupled with the exhaust draw, but what matter is that anyway. It's dry. Fly ash can be greatly minimized with a good spark arrestor and a hot fire, two things every wood stove should have anyway. We had no issues running our stove in the slip, no one was there anyway when it was cold enough to need it.
 
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