Condensation

[Woodford]

I know I sound like a cracked record repeating the same old things every time condensation threads start, BUT warm moist air and cold surfaces do not mix without producing condensation. No ammount of eco fans or increased heat is going to eliminate condensation as long as there are cold surfaces for it to appear on. When it comes to boats, people seem to ignore all the lessons learned and taken for granted over years of housing development.

 

It's all basic physics which is why modern housing has insulated cavity wall construction, double glazed windows and thick roof insulation. That keeps the warm air in the house away from the cold outside and stops heat and cold transfer.

 

If you live in a tin or grp tube with no barrier between inside and outside surfaces, then you will loose your heat and have severe condensation problems. If you heavily insulate ALL surfaces of your boat that have contact with the outside and double glaze all your windows then you eliminate nearly all condensation and retain your heat. You also need to reduce moisture production and maintain normal ventilation levels to allow fresh air to enter the boat. The ventilation will help drier air enter and also stop you suffocating

 

Don't under estimate the ammount of moisture produced on a boat from breathing, washing, drying clothes, cooking etc. A given volume of air can only absorb a certain ammount of moisture before it becomes saturated, and the volume of air in any boat will be a small percentage of that in a house for a similar moisture production. So the air in the boat will become saturated much sooner and any cold surface remaining will precipitate condensation.

 

Because cupboards and under bed areas are usually poorly insulated and ventilated on boats, they are usually major areas of condensation and mould build up so also need properly ventilating.

 

Finally, poor window, cabin wall and roof insulation will allow the warm air to rise and transfer out of the boat, while colder air from window glass, and colder surfaces will always descend being heavier, given constant cold draughts and air movement, most noticeable around your shoulders, back and legs when sitting near windows.

 

Roger

 

I agree - we are fortunate in that we have around two inches of insulation all round - probably a major contributory factor in eliminating condensation.

Our new top hatch covers are lined with two layers of marine ply and the light prism is insulated from the surrounding steel - we expected to get the occasional drip from condensate on the prism but it remains nice and dry even last night when it was below zero outside.

[ditchcrawler]

I use a pressure cooker a lot during the winter too,a big saving on gas,and if you keep it just below blowing off pressure not much water vapor escapes and as long as you take the thing outside when opening it.

I also boil up my socks in.

Before or after lunch?

[Androo]

Not having a dig at you bottle, but everytime condensation comes up "ventilation" always seems to be the response from the forum. However, we all know that our boats (are supposed to) have an adequate area of fixed non-closeable vents. So assuming they have, is anyone seriously suggesting we also leave windows open all night at this time of year?

 

We always leave the window open nearest the bedroom 24/7 for fresh air and ventilation. Just get under your duvet and enjoy it!

[bizzard]

Before or after lunch?

Before, quickly sometimes before the quests arrive.

[Tinally]

My friend has just bought a cordless window vacuum cleaner to deal with the condensation on his cottage windows. It is extremely efficient and saves all that mopping with cloth or tissues!

 

 

You can, incidentally, get a smaller head for it, so you can get into awkward places!

Edited December 17, 2011 by Tinally

[nina]

My friend has just bought a cordless window vacuum cleaner to deal with the condensation on his cottage windows. It is extremely efficient and saves all that mopping with cloth or tissues!

[bizzard]

My friend has just bought a cordless window vacuum cleaner to deal with the condensation on his cottage windows. It is extremely efficient and saves all that mopping with cloth or tissues!

 

 

You can, incidentally, get a smaller head for it, so you can get into awkward places!

I can't wait for a drop of condensation on my windows,and then just go at em with a clothe,best way to clean em.

[Smelly]

Stop breathing...

 

Lungs are undoubtedly the single biggest source of water vapour and it's going to end up somewhere.

 

Or live with it

[blackrose]

 

 

Yes, we have at least one porthole open at all times in the bedroom and another in the engine/ back cabin area.

 

The boat is warm and the only condensation this morning was on the metal surround on the kitchen roof hatch, this has now gone.

 

Well I keep all my windows firmly closed and my boat doesn't suffer from any condensation problems. Since the boat has adequate fixed ventilation I see no reason to let the wind whip through additional open windows, letting the heat out.

Edited December 18, 2011 by blackrose

[Tiny]

If you are connected to an electric supply the delonghi babino 500watt oil radiator heater gives out an amazing amount of heat for its size. On a low setting it warms our bedroom - which due to a sloping roof lack insultaion - and keeps this 13'x13'x8' room nicely warm on a low setting being on about half the time. And, apart from a tiny on/off click it is silent.

[Robbo]

If you are connected to an electric supply the delonghi babino 500watt oil radiator heater gives out an amazing amount of heat for its size. On a low setting it warms our bedroom - which due to a sloping roof lack insultaion - and keeps this 13'x13'x8' room nicely warm on a low setting being on about half the time. And, apart from a tiny on/off click it is silent.

 

Central heating and oil radiators won't help with keeping condensation down, in fact if your using this instead of heat from a stove then it will be making your condensation worse. A stove brings in fresh dryer air from outside as well as keeping the air moving.

 

If you are connected to a electric supply then a decent dehumidifier will help.

Edited December 18, 2011 by Robbo

[NB Alnwick]

Stop breathing...

 

Lungs are undoubtedly the single biggest source of water vapour and it's going to end up somewhere.

 

Or live with it

 

As has been said many times, condensation occurs when warm moist air comes into contact with cold surfaces - i.e. surfaces that are well below the ambient temperature. To prove this, just place a small glass in the fridge, leave it to cool, then remove it and breathe on it - condensate will form on the glass. In most cases condensate will still form even if one could stop breathing because the air will always contain a degree of moisture - so the best way to prevent condensation is insulation and temperature control. If there are no exposed areas that are significantly below the ambient temperature condensation will not occur.

 

From my own observations, I would say that the boats I have seen that suffer the effects of severe condensation, all have poorly designed insulation . . .

[nina]

Thanks again everyone for your input. It's not a huge problem on our boat and I have found, despite protests from my husband, that if I open the side hatch while cooking, it makes a huge difference. We're only on our boat during evenings. Our work commitments mean where out all day so it doesn't get a build up of ongoing condendation. I dry all the windows before leaving in a morning. I just wondered if it might effect the wood interior in the long term. As some posters have said, teak oil on a regular basis will help preserve.

[Québec]

I'm going to undertake some tests and observations....because we woke up this morning to be greeted by heavy condensation on all the windows. The stove had been on all night, the blinds were shut, the only windows we had open were a porthole at the rear and the small bathroom hopper, the mushrooms on the roof were all open, and it was c. -2 degrees outside and c. 18 degrees at mid-height on the boat. However...once we'd raised the blinds and wiped the condensation off, and we were up and about, the windows stayed dry, although the stove stayed on - even hotter - and it stayed at or below freezing outside. There was certainly increased ventilation as we opened a couple more windows and went in and out of the boat, but even when were just sitting reading the papers, there was no condensation forming.

 

So there would seem to be a set of conditions on our boat ( and of course it's ONLY on our boat) which, together, form a 'tipping point' when condensation forms. The aim is to find the point just before it 'tips', trying to find the minimum ventilation required to prevent serious condensation (don't mind and accept we'll get some): which window to leave open?does closing the blinds make a significant difference re: lack of air flow around them? Etc.

 

I'm also going to try and find out if putting bubblewrap over the windows actually makes a difference. We put it over the windows last year during that really cold weather, and my impression was that the boat seemed easier to keep warm AND there was less condensation on the windows.

[Naughty Cal]

I'm going to undertake some tests and observations....because we woke up this morning to be greeted by heavy condensation on all the windows. The stove had been on all night, the blinds were shut, the only windows we had open were a porthole at the rear and the small bathroom hopper, the mushrooms on the roof were all open, and it was c. -2 degrees outside and c. 18 degrees at mid-height on the boat. However...once we'd raised the blinds and wiped the condensation off, and we were up and about, the windows stayed dry, although the stove stayed on - even hotter - and it stayed at or below freezing outside. There was certainly increased ventilation as we opened a couple more windows and went in and out of the boat, but even when were just sitting reading the papers, there was no condensation forming.

 

So there would seem to be a set of conditions on our boat ( and of course it's ONLY on our boat) which, together, form a 'tipping point' when condensation forms. The aim is to find the point just before it 'tips', trying to find the minimum ventilation required to prevent serious condensation (don't mind and accept we'll get some): which window to leave open?does closing the blinds make a significant difference re: lack of air flow around them? Etc.

 

I'm also going to try and find out if putting bubblewrap over the windows actually makes a difference. We put it over the windows last year during that really cold weather, and my impression was that the boat seemed easier to keep warm AND there was less condensation on the windows.

 

As you say each boat and each set of owners will have different points at which condensation becomes a major problem. On our small boa we dont seem to suffer too badly but the boat is double skinned which helps with insulating, has small port lights and hatches and we are able to provide adequate ventilation by having the hatches open on the ventiation catch and the port lights open. We dont have background/trickle ventilation on board, being a sea boat NC doesnt have to have any so it is important that we provide the ventilation by opening the windows. It doesnt mean that the boat is cold however as the heating takes care of the room temperature automatically.

 

We all live our day to day lives in different ways so will produce vastly different amounts of water vapour per person. How we cook, clean and breathe will affect this. We have found that using the slow cooker over the weekend produced far less water vaspour than how we would normally cook on the hob

[nina]

As you say each boat and each set of owners will have different points at which condensation becomes a major problem. On our small boa we dont seem to suffer too badly but the boat is double skinned which helps with insulating, has small port lights and hatches and we are able to provide adequate ventilation by having the hatches open on the ventiation catch and the port lights open. We dont have background/trickle ventilation on board, being a sea boat NC doesnt have to have any so it is important that we provide the ventilation by opening the windows. It doesnt mean that the boat is cold however as the heating takes care of the room temperature automatically.

 

We all live our day to day lives in different ways so will produce vastly different amounts of water vapour per person. How we cook, clean and breathe will affect this. We have found that using the slow cooker over the weekend produced far less water vaspour than how we would normally cook on the hob

 

 

Can vouch for this. A slow cooker is a good investment because it reduces steam.

[Naughty Cal]

Can vouch for this. A slow cooker is a good investment because it reduces steam.

 

It also makes the best succulent chicken

[nina]

It also makes the best succulent chicken

 

 

Yep! :-) I cook a heap of stewing steak cubed, with the fat off, onions, red wine, seasoning, etc. Freeze it in portions, then take 2 out at a time, put them in a pie dish, add a puff pastry top (ready made) and make a proper pie. Really nice. When we run out, we have to use the good old Fray Bentos pies but they're not bad to have in reserve.