cabin roof condensation

[chrisarvor]

i have a new arvor fishing boat and in the cabin above the V berths on the ceiling we are getting condensation , quite a lot!.
i leave the large vent open on the starbord side, its like a quarter light onthe old cars the ceiling above the berths has no lining its just the fleck paint .
Should i line the ceiling or put another vent in OR buy a low heat tube heater and leave it on .any advice

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[davidwf]

If you have mains power buy a dehumidifier, B&Q do a wide range starting at around £90. This will cure the problem completely. If you havn't access to mains I think more ventilation is the best option.

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[johnsomerhausen]

I know the problem... had a boat that had tremendous condensation. Tjhe easiest solution is to fasten polysterene foam panels (or better, polyurethane ones) on the roof with contact cement and then cover those up with some fabric.
john

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[muchy_]

I had the same problem with my first boat. I used foam ceiling tiles with contact adhesive then thin foam then fabric covering, worked a treat. Looked good too. The other thing you could try is that carpet material stuff they use. Easier to put up than the method I used and probably works just as well. Comes in some nice colours as well.

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[Johnjo]

I have used the carpet material option in my cabin, The only condensation I get is on the windows.
Not to difficult to do, and IMHO looks pretty good as well.

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[malcp]

If you don't have mains power try one or more of the crystal de-humidifiers one can get. Although not as effective as the mains powered ones they do help. These can be found in caravan shops as well as chandleries.

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[Talbot]

If you are going down the carpet roof, recommend that you use feltback carpet. The foam will eventually get brittle and fall apart, it is also not as easy to glue.

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[tcm]

all your ideas will reduce condensation: insulate the place, increase ventilation (but it mite get too cold at night) and increase the temperature with a heater.

Expect condensation on every single cold surface which damp air can reach. I have used self-adhesive flameretadent foam under a headlining, also heard that cork tiles are possibility. If you are getting condensation on the roof, also look under the mattress - good chance it is damp and going (or gone) mildewy: clean the mildew with mild bleach solution, elminate it by putting in a layer of thick "builders board" - hard polystyrene, often blue coloured under the mattress. Even with all this, any interior metal parts (which cool fastest hence most at risk to having condesnation) need a coating of protective stuff eg spray WD40, and then wipe excess off : everything - hinges, handles, light fittings, switches and even taps. Spray it on, wipe it off. If your vent has rubber seal, then don't use wd 40 on it or it'll rot - use a silicon based lubricant or vaseline spray, same with portholes windows.

hope this helps

imho

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[NigeCh]

I\'ve posted about condensation several times

Let's analyse the problem: Small space + bodies breathing: The average person breathes out or sweats about 450 ml water per night. At night the external temperature tends to fall in the UK by about 8 C over the max daytime temperature. The internal surface temperatures in the cabin fall according to the insulating qualities of the surrounding external surfaces. Condensation occurs when the internal surface temperature of the exposed elements falls to and below the dew point of the internal air. (Dew point is a function of saturated vapour pressure and temperature)

To prevent condensation on external surfaces you have to maintain the dew point temperature at the external surface above its critical level. To do this you first MUST create a vapour barrier on the warm side and then add non-permeable insulation between the vapour barrier and the external surface.

Assume an external temperature of say 5 C and an internal cabin night time temperature of 12 C. You will need a MINIMUM U-value of 2.0 to prevent condensation. From what you are saying it seems that the U-value above the berths is somewhere between 3.8 and 4.6 - and that will allow condensation at night when the external temperature falls below 9 C. You can alleviate condensation by having an air crossflow to bring the internal air temperature and vapour content down to the same as the external air - but then you would start to get cold unless you had a 4 season sleeping bag.

Correct insulation (with a properly positioned vapour barrier) and a small degree of crossflow ventilation will solve all your problems. If you want professional advice then PM me.



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[chrisarvor]

Re: I\'ve posted about condensation several times

i forgot to say we dont sleep on the boat , its when we open the cabin after we have been out the previous day we find our centre cushion wet there is also moisture on the wall behind the helm position

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[NigeCh]

Then, in which case

all you need is permanent crossflow ventilation to maintain the internal/external air temperature/RH's at the same levels. Make sure that the ventilation outlet is as high as you can get it and that the intake feeds external air around and through the bilge.

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[duncan]

Re: I\'ve posted about condensation several times

I have an almost identical boat and suffer the same problems.
Without mains electricity (|I do have a dehumidifier!) I am left with removal of cusions and a sponge for the areas that suffer from the 'dripping' and a generous spray of WD40 all over the electrics.
I do notice the same thing in the summer even when the hatch is left fully open!
Nice built in f/glass liners seem to magnify the problem.

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[Lofty]

Try cork tiles. They bend easily, stick well with Evo-stick and provide excellent insulation. Head lining can then be stuck on top. To stick the headlining I used Silicone sealant which I spread with a paint scrapper. If you don't get it right the first time you can always try again which is not possible with Evo-stick and mastic is about the cheapest adhesive you can get.
Good luck.

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[nictbrown]

I once fitted pvc strips from Wickes etc used to line bathrooms - about 100mm wide and slot into next one. These have an air space in so insulate a bit and look good. Very cheap too.

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[Abigail]

We do live aboard, and over this summer have insulated the boat throughout with 9mm closed cell foam stuck all over the bulkheads to below the water line (yes it took forever!). Over this we've either replaced (and are still replacing as it takes ages) the headlining on plywood - or stuck on carpet of the kind you get in cars. We got this at good value from an RV fit out store (much cheaper than the ordinary squares you buy in car supply shops).

Only problem recently discovered has been inthe centre of the aft cabin mattress, which sits over a deep locker with the quadrant in that we had not managed to insulate. We have stuck closed cell foam on the underside of the hatch, and that seems to be doing the trick.

Hope this helps.


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