under bunk condensation - what really works

Trop Cher said:
When this subject has come up previously, someone suggested using lengths foam pipe insulation. This year I tried this and it works, a few lengths of pipe insulation, some tape, a pair of scissors and half an hours easy work and the job's done!
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Probably me, see #12 ;)
But use cord, push short tube cord through long tubes with a big needle.
 
superheat6k said:
Doesn't the capillary matting end up waterlogged ?
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Sailorman is correct. We always had a wet patch verging on small puddle in previous boat. Cushion had a vinyl bottom and sat on fibreglass, so nowhere for the water to go. Capillary matting never even felt damp and moisture obviously spread through the mat and evaporated (capillary action & high surface area?).

Didn't get a puddle on current boat as the cushions don't have vinyl underneath. However, they did get pretty damp before laying down capillary mat.

You'd have to dip an end in a bucket of water before the underside of the bunk would get wet on our boat.
 
Mistroma said:
Sailorman is correct. We always had a wet patch verging on small puddle in previous boat. Cushion had a vinyl bottom and sat on fibreglass, so nowhere for the water to go. Capillary matting never even felt damp and moisture obviously spread through the mat and evaporated (capillary action & high surface area?).

Didn't get a puddle on current boat as the cushions don't have vinyl underneath. However, they did get pretty damp before laying down capillary mat.

You'd have to dip an end in a bucket of water before the underside of the bunk would get wet on our boat.
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My mattresses sit in a recess right around the berth about 25mm deep, effectively sealing off any ventilation at the edges - will the capillary mat still work - its certainly cheap compared with the 9 - 12 mm spacer fabric ?
 
superheat6k said:
My mattresses sit in a recess right around the berth about 25mm deep, effectively sealing off any ventilation at the edges - will the capillary mat still work - its certainly cheap compared with the 9 - 12 mm spacer fabric ?
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Both current and previous boat had well recessed cushions. Previous lay on solid fibreglass against fibreglass liner and wooden bulkheads either end. The open side had a wooden lip approx. 3"-5" (or more) high. Current boat has a 2mx2.1m berth open at bottom and enclosed on other 3 sides (bulkhead and storage lockers).

Matting worked in these locations though we also have insulation laid on top of tank under berth in current boat. It is cheap enough to try before spending a lot on a "marine" solution.
 
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Martin&Rene said:
In my opinion, most of the views on underbed condensation work on the principle that improving ventilation could reduce the problem.
So I think the major way to avoid condensation is to prevent warm moist air coming in contact with a cold surface. Sailing in Scotland, the water temperature varies between 8 and 14 deg C and so the bilges are probably around this sort of temperature. (Great for storing wine and beer) Earlier this year I finally finished insulating under the fibreglass bed bases in the back cabins using 25mm PIR insulation board.

http://www.jewson.co.uk/building-ma...l-eurothane-gp-insulation-2400-x-1200-x-25mm/

I stripped the aluminium foil of one side and glued the board underneath the bed bases using Evostik Serious Stuff or Stick Like Sh*t adhesive or Unibond No More Nails.


I reckon that's an interesting solution and worth a try. I'm going to give it a shot on my boat.
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I do not know why, but on my original entry, the full web address did not appear. Look up using this in google, or go to the Jewsons website..

Recticel Eurothane GP Insulation 2400 x 1200 x 25mm
 
LadyInBed, would you mind sharing photos of your solution so I can see how to construct it?

We still have a problem with condensation under the mattresses when we sleep on our boat (A Sun Odyssey 30i) even with a dehumidifier. Would be nice to have a permanent solution!
 
ZoeImogen said:
LadyInBed, would you mind sharing photos of your solution so I can see how to construct it?

We still have a problem with condensation under the mattresses when we sleep on our boat (A Sun Odyssey 30i) even with a dehumidifier. Would be nice to have a permanent solution!
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I did this
View attachment 55311
Holes in the bunk boards and IKEA slats cut to size and screwed to the bunk boards so they can still be lifted. I also insulated the hull beneath with 20mm closed cell foam.
 
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