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Puppies
Puppies

Posted: Sun Jan 19, 2014 5:21pm

Post Subject: Condensation problems

I am looking at injecting expanding foam below the gunnels for the bedroom (reverse layout) for my narrow boat in the void space between the paneling and the steel side of the boat. Could you please advise on a fire retardant product that has minimal expansion while setting as I do not wish to swell out the paneling. Do you have a procedure for injection, distance between holes, test holes for relieving pressure etc. The boat is spray foamed with expansion foam above the gunnels. I believe this is the right time to do the job as the void pace is wet. We have all vents clear on the boat and windows cracked open with wedges. The cold pipes have been insulated and a dehumidifier bought recently. The window seals have been checked and the filling line and fresh water tank is tight but a lot of condensation seen on the tank from the bedroom. We are still getting wet pillows, sheets and duvets that are in contact with the paneling.

Tony-B
Tony-B

Posted: Sun Jan 19, 2014 7:20pm

Post Subject: Condensation problems

You are asking for the technical instructions on how to undertake what I consider a very ill thought out scheme. I must advise you to research such products and the contact the manufacturer. What makes you think there is no insulation against the hull? Have you taken a panel off to check? The "normal" procedure for spray foaming is to do it before the paneling is fitted, this goes for any type of insulation. I also suspect that for large areas in a confined space you may well need respirators. I would also be very wary of the prospect of trapping moisture between the foam and steel. I am not sure about the corrosion implications. My advice would be to remove as much paneling as you can and if no insulation is present install closely fitting fire retardant polystyrene sheet or Kingspan/Celotex. Is the bilge absolutely dry? Are you sure the widows are not leaking between the frame and cabin side? If any other readers have attempted this please will they advise. Tony Brooks

Tony-B
Tony-B

Posted: Sun Jan 19, 2014 7:21pm

Post Subject: Condensation problems

PS "window Seals" are generally taken to be the rubber situated between the glass and frame plus the foam the hoppers sit against. Not the materiel between the frame and cabin side.

foamofobic
foamofobic

Posted: Mon Jan 20, 2014 1:08pm

Post Subject: Condensation problems

Hi there. We met up while out walking the dogs:) ... I think I agree with Tony B. I think the problem will still happen even if you fill up the void with foam insulation. As soon as you rest bedding against the side panelling, you will create a thermal gradient that will be affected by changing temperatures inside and outside, and also variable amounts of water laden air. A perfect drop zone would be between the bedding and the panelling. We overcame this problem by putting a layer of thin foil insulation between the bedding and the panelling. But even then, in extremes there will always be the case where damp will form. then it a good idea just to move the bedding out once in a while just to remove the damp and let some warm air in .... hope this helps

Tony-B
Tony-B

Posted: Mon Jan 20, 2014 1:45pm

Post Subject: Condensation problems

Another thought. You an get a product that looks like horsehair covered in latex. This comes in sheets of about 20 mm thick and is totally porous so air can circulate through it. If you place sheet of this under the mattress and bend it up against the cabin side so it holds the mattress away from the panels it will allow a circulation of air to vent dampness from within the mattress and also from the air to vent away. Have a look here: http://www.naturalmatmarine.co.uk/anti-condensat ion-underlays/ Tony Brooks

Puppies
Puppies

Posted: Tue Jan 21, 2014 10:09pm

Post Subject: Condensation problems

Thank you for your advise, I will wait until docking is due and consult yard. To answer your questions, yes the boat has been spray foamed below gunnels but mean in thickness,very cold to touch and wet of course. Behind the angle iron that secures the battens your get rust on finger tips. The boat is 11 years old and the windows are Channel Glaze de lux double glazed. The frames were secured with hardened wood screws and when the rubber seal was removed majority of heads had rusted off along the bottom. A maker's recommended repair was carried out with stainless steel screws. All have been done. With regards to the bilge, at the bilge point down aft, the inspection hole has 2 layers of paving stones that is lying on sand, I have removed a good bit of the top one,but the bottom one is being obstinate. I can say there is less than 1 1/2" down there but it is damp. I am sure it will dry out in the summer. I will probably go for the skin between the mattress and ply paneling. I do not wish to remove the paneling.

Tony-B
Tony-B

Posted: Wed Jan 22, 2014 8:35am

Post Subject: Condensation problems

Did you take the whole window out AND treat any rust on the cabin side? If not are you aware that when steel rusts it expands by about eight times and can push the frame away from the seal. Did you take any steps to seal the gap between the crews themselves and the frame? I wrapped sealer strip around each screw before inserting so some oozed out as the screw was tightened. I am not saying either are the problem but may be worth checking. If the whole bilge area is full of paving slabs set in sand then I fear the sand will retain an awful lot of water and will do nothing for hull life. See if you can install bilge vents fore and aft so there is a chance of getting a through bilge flow of air. If you have an electric fridge it may also be worth cutting a vent in the floor below the radiator in the back and fitting a computer fan, controlled by the fridge's control box so it blows bilge air over the radiator on the back. 12V fridges have a special pair of terminals for this. This would forced an airflow through the bilge. Remember any damp or water in the bilge makes a big difference to condensation. Tony Brooks

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