Condensation

[tonyreptiles]

Hi All,

 

I've just changed the undersheet on my bed and it is almost black with mould.

My bedroom is at the stern of my 50' trad running lengthways down the port side.

I have two portholes either side of the boat and a (closed) pigeon box in the centre of the bedroom.

The (unvented) door to my engine room is always closed but the bedroom door to the rest of the boat is always open. (We always bank up the fire to ensure a warm morning.)

 

Ms TR complains that she is sometimes dripped on from above as she sleeps closest to the side of the boat.

The side walls are sometimes wet but only in small places, however the wooden bed base panel beneath the matress is wet and mouldy in the corner.

 

I think it is a ventilation issue as the warmer the fire and the colder the outside the more drippage we get. However, how can I ventilate without getting cold. I don't feel comfortable banking up the fire only to lose all of the heat through the pigeon box.

 

Please help. I have sorted out all of the other heating problems with my boat and only this one remains.

 

TIA

 

TR

[cheshire~rose]

I've just changed the undersheet on my bed and it is almost black with mould.

 

I will let other people who are far more experienced in the best practice on boats than me respond to the heating/ventilation question

 

However I would suggest (assuming that you do not already do so) when getting up in the morning throw the covers right back and leave the mattress open to air. if the weather outside the boat is dry then take the opportunity to open the windows in the bedroom and get some ventilation in. you can close the door so the rest of the boat does not get cold.

[blackrose]

You should only need one mushroom or other roof vent and a vent in the door, so rather than ventilation, think insulation. You don't say what insulation you currently have.

 

Condensation only occurs where warm air meets a cold surface and the water vapor in the air condenses out onto that surface. The sprayfoam in my boat isn't the thickest but the only condensation I ever see is on the portholes and the aluminium frames, and where my steel doors meet. If your insulation is insufficient but you don't want to rip off the lining, depending on what's in there already it's possible to do a cavity wall job with handheld cans of fire rated sprayfoam (cheapest on ebay). It's messy but if you think it through & work methodically it's possible. If you decide to do this PM me & I'll give you some tips.

Edited February 16, 2007 by blackrose

[Pirate]

I have seen this from the cross members in the roof before, and worse in the bedroom because of the slope to the rear, it will run along to back of boat, remove the side roof panels and inject foam into the ends of each cross member, then they will be filled with air that should act as a barrier...best of luck

[Roger Gunkel]

This is a condensation problem that has existed for as far back as I can remember but is quite easy to rectify.

 

The reason for the condensation is not neccessarily moisture from the general atmosphere condensing on a cold surface, but more the heat from your body warming the mattress, and allowing the moisture from your body being absorbed into the matress and condensing on the cold wood underneath.

 

To cure it, depending on your type of bed base, you need to allow a completely free flow of air through the base and the bottom of the matress. The easiest way is to either replace the base board with evenly spaced slats, or to make a simple frame base and stretch webbing across the frame as a support for the matress. You could also try removing the base board and cut a large number of 1.5 to 2" holes all over the board to completely ventilate it. Make sure that which ever way you do it, air is also able to circulate in the storage space under the new bed board. If you have difficulty removing the base board, it sometimes helps to cover the top with foam backed carpet to put another insulator between the wood and the matress, but this doen't work in all cases and proper under ventilation is far better.

Good luck,

Roger

[dor]

A friend solved this problem with some proprietary bendy slats. They were curved, but when you were in the bed they flattened; but with no weight on the bed they had enough spring to lift the matress enough to allow air to circulate.

 

It's a common problem, perhaps exacerbated by having a pidgeon box over the bed. The pidgeon box on a warm boat on a cold night is probably about as efficient as you can get as a passive dehumidifier; only problem is the condensate has no option but to drip onto your bed.

[blackrose]

This is a condensation problem that has existed for as far back as I can remember but is quite easy to rectify.

 

The reason for the condensation is not neccessarily moisture from the general atmosphere condensing on a cold surface, but more the heat from your body warming the mattress, and allowing the moisture from your body being absorbed into the matress and condensing on the cold wood underneath.

 

To cure it, depending on your type of bed base, you need to allow a completely free flow of air through the base and the bottom of the matress. The easiest way is to either replace the base board with evenly spaced slats, or to make a simple frame base and stretch webbing across the frame as a support for the matress. You could also try removing the base board and cut a large number of 1.5 to 2" holes all over the board to completely ventilate it. Make sure that which ever way you do it, air is also able to circulate in the storage space under the new bed board. If you have difficulty removing the base board, it sometimes helps to cover the top with foam backed carpet to put another insulator between the wood and the matress, but this doen't work in all cases and proper under ventilation is far better.

Good luck,

Roger

 

Hang on Roger, sorting out the bed won't cure the condensation on the walls & the dripping from the ceiling!

Edited February 16, 2007 by blackrose

[Roger Gunkel]

Hang on Roger, sorting out the bed won't cure the condensation on the walls & the dripping from the ceiling!

Yes Mike you are absolutely right, but I think that the main concern that TR had was the damp and mould on the undersheet and bed base. Even if the rest of the condensation is completely removed, it won't stop the bed problem which is really a seperate issue. I agree with your advice and others on the wall and ceiling moisture, but that has been well documented on other threads so I ignored it, whereas the bed base one I haven't seen questioned before.

Roger

[blackrose]

Yes Mike you are absolutely right, but I think that the main concern that TR had was the damp and mould on the undersheet and bed base. Even if the rest of the condensation is completely removed, it won't stop the bed problem which is really a seperate issue. I agree with your advice and others on the wall and ceiling moisture, but that has been well documented on other threads so I ignored it, whereas the bed base one I haven't seen questioned before.

Roger

 

Fair enough!

[Roger Gunkel]

Fair enough!

[nbtafelberg]

You can cure condensation on windows by wiping them with washing up liquid.

[NB Alnwick]

I've just changed the undersheet on my bed and it is almost black with mould.

 

There are several issues here that, so far, have not all been addressed:

 

First, everybody loses moisture through their skin while they sleep - and it needs somewhere to go. This is usually dealt with by ensuring adequate air circulation under the mattress. If the mattress itself is of a design that does not allow the moisture to escape - then it should be replaced with one that 'breaths'. The important thing is to ensure good circulation of ventilating air around and under the mattress.

 

Second, good insulation is necessary to prevent condensate gathering on relatively cold surfaces. If condensate accumulates - then the insulation is insufficient and needs to be improved. If you have large windows consider double glazing.

 

Third, mould and mildew is potentially hazardous, especially to sufferers with Asthma and other respiratory problems, and in itself it attracts moisture. Treat the mould with a good disinfectant such as 'Dettol' - I would add some diluted disinfectant to the rinse when washing the sheet and wipe all the wood and mould covered surfaces with neat disinfectant.

 

Lastly, avoiding damp depends on good insulation and good ventilation - its not rocket science . . .

[Oliver]

You can cure condensation on windows by wiping them with washing up liquid.

 

 

Clevett

 

Diluted washing up liquid or neat? Do you have to wipe the windows everyday? Does it work on houdini hatches?

 

Could be the answer I need to stop him in doors grumbling every morning.

[DHutch]

The washing up liquid mearly works by forming a layer which reduces the formation of condestation.

- Commerical products are also avalable in the car market, i think Holts do one called "Anti-Mist Spray" in a blue pumptop bottle.

- Its not a replacment for good ventialation or double glasing, but it can help, espically if only use it a a few windows..

 

 

Daniel

[greyowl]

Just as a matter of interest, would having plants onboard help the moisture problem, or make it worse ?

 

kris

[Theo]

Just as a matter of interest, would having plants onboard help the moisture problem, or make it worse ?

 

kris

 

 

If it makes any difference it will make it worse. You need to water the plants so there is evaporation from the soil surface and the plants themselves transpire in order to draw water, the transport fluid up from the roots. This means that the leaves give off water vapour. I seem to recall that a mature oak tree will put an extra 40gallons of water per day into the atmosphere. The clouds over the Amazon tropical rainforest are formed from the water vapour pumped into the air by the trees.

 

My advice, therefore, is not to plant an oak tree in your cabin and leave it there for too long and avoid the spread of tropical rain forests next time you are cruising the Amazon.

 

Nick

[DHutch]

Yeah, i was going to say roughly the same.

- Wont make a huge diffrence, but that that is does will be counter productive.

 

 

Daniel

[Miracle]

i've just realised that i have a simillar issue with the bed. although not black yet!! I have purchased a roll of rubberised coir to cut to size which should allow the ventilation.

i chose it based on the description from another boater as to swhat she had (course looking rubberised pubes in a matt) is what she claimed it looked like, and that it was used in the ychat industry) FINGERS CROSSED i've got the right stuff. otherwise, back to the drawing board.

[chazzy]

I think with all condensation problems, if you have a shoreline consider a dehumidifier. Once a surface reaches the dew point condensation forms on that surface, cools it more thus drawing more moisture. humidity isnt just confined to the air within the boat but all soft furnishing even carpets can contain the same moisture content as the air. It is also said 2 people asleep during the course of the night can add up to 1 1/2 pints of moisture to the air.

[Taslim]

Hi.

 

We have been here before.

My 'temporary ' solution, which is still in place five years on, was to put light weight slatted pallets under the mattress. Two small computer fans move the air during the day. The saloon / sleeping area is still subject to some condensation despite being quite well ventilated but the pallets have cured the soggy mattress prob.

 

Hope this helps.

 

taslim.