Condensation when staying onboard!

[Matt341]

Hi All,

We previously owned a Mirage 28 which we rarely stayed onboard but when we did we never had any condensation, the upholstery could be left on all winter with no heating or dehumidifier.

However, we now own a Westerly and stay onboard for weekends & holidays. Over the winter we kept a couple of tube heaters on due to the extremely cold weather. All was fine over the winter and the upholstery was dry and the boat felt damp free. We didnt stay onboard though. However, we have been staying onboard for the last few weekends and the condensation is becoming a real problem and we dont know if we can face anymore of it!!

We use a 2kw convector heater that we keep on low from early evening and when cooking ensure that the hatch is open.

The windows are all metal framed and by 11:00 they tend to start condensing and around midnight they start dripping over us. We tried drying them but they just condense again.

Its not just the windows, the hull also condenses up the bow cabin and even though its lined with a thick foam headlining it still appears. By the morning the bedding is really wet where it has been against the hull and underneath the cuhsions are also wet. We have to use a hairdryer to dry off the bedding and the cushions are propped up for a few hours to dry out.

The main cabin also condenses but not as bad as the bow cabin or heads. The heads is really bad with condensation just about everywhere in there.

Its really starting to become a concern now and I really dont know what to do. Are these mositure absorbing crystals worth a try? Or maybe a dehumidifier but would this really prevent such a huge amount of condensation?

Advice will be greatly appreciated.

Thanks
Ian

 

[sailorman]

Hi All,

We previously owned a Mirage 28 which we rarely stayed onboard but when we did we never had any condensation, the upholstery could be left on all winter with no heating or dehumidifier.

However, we now own a Westerly and stay onboard for weekends & holidays. Over the winter we kept a couple of tube heaters on due to the extremely cold weather. All was fine over the winter and the upholstery was dry and the boat felt damp free. We didnt stay onboard though. However, we have been staying onboard for the last few weekends and the condensation is becoming a real problem and we dont know if we can face anymore of it!!

We use a 2kw convector heater that we keep on low from early evening and when cooking ensure that the hatch is open.

The windows are all metal framed and by 11:00 they tend to start condensing and around midnight they start dripping over us. We tried drying them but they just condense again.

Its not just the windows, the hull also condenses up the bow cabin and even though its lined with a thick foam headlining it still appears. By the morning the bedding is really wet where it has been against the hull and underneath the cuhsions are also wet. We have to use a hairdryer to dry off the bedding and the cushions are propped up for a few hours to dry out.

The main cabin also condenses but not as bad as the bow cabin or heads. The heads is really bad with condensation just about everywhere in there.

Its really starting to become a concern now and I really dont know what to do. Are these mositure absorbing crystals worth a try? Or maybe a dehumidifier but would this really prevent such a huge amount of condensation?

Advice will be greatly appreciated.

Thanks
Ian

Ventilation or dry heat is the only real answer.
We sleap in the "Forrard" cabin with the hatch open to what ever the weather will allow, we do get condensation on the bunk top under the cushion. ther are product available to place between the bunk top & cuschion.
metal framed windows will always be a problem due to being cold

 

[Humblebee]

Dehumidifier

A dessicant type dehumidifier from Boatsheen transformed the comfort of our boat. Highly recommended if you have shorepower. The crystal thingies do soak up some moisture and we use them when away from shore power but in winter, living aboard, I reckon nothing beats the dehumidifier.

 

[Pete735]

Minimising Damp Beding

As has been said, increased ventilation ought to help the general problem.

One improvement for us has been buying from Libs this year one of these "mats" that fit under the bed foam and provides an air barrier between bedding and horizontal supporting surface. It has helped considerably and it was large enough to allow it to run up the sides of the boat a few inches. Details are on the boat and I cannot remember suppliers name, but we have certainly been pleased with it so far.

 

[Fr J Hackett]

We bought the wooden slats from Sibs and found them to be very effective in reducing dampness under the berth cushions in the forepeak

 

[MoodySabre]

Slats cheaper at Ikea!

We have an ECS Solar Air vent in the forecabin hatch vent and vents in the washboards - now admittedly it doesn't work in the dark but we don't get any condensation (well a little on the windows this time of year but not enough to do anything about).

 

[DannyB]

If you want to go down the dehumidifier route, I can recommend the DD 122 from Meaco, this is the one PBO recommended after their tests. I bought one and it works great, it's also very quiet. I run mine overnight draining into the sink, and it continues to work even when the temperature drops.

 

[idpnd]

Your other option would be to keep the temperature fairly stable. If you heat up the air during the day it has high moisture potential, when temp drops at night (due to switching heater off I guess) the moisture condenses. So you could try heating it up less or just keeping it hot hence it shouldn't condense (as much)

 

[Robin]

Ventilation Ventilation ventilation!

It sounds like the boat is shut up tight except when cooking and that doesn't work at all. People breathe out tons of water just staying alive and it simply condenses on the coldest surfaces available. You obviously have power on so a thermostatically controlled heater run all night but with the hatches also cracked open will do the job pretty well, although there will be some moisture on the windows & frames.

We slept up front in all our boats including a Westerly 33 and on our berth with power available always ran a thermostatically controlled fan heater on a low setting overnight, but the forehatch was always open an inch and at least the top washboard left out with the mainhatch slid shut. We used a proper de-humidifier all winter when not on board but that went home once we were in sailing somewhere trim so it never went for a ride.

 

[mawm]

Warm air can hold more water as vapour than cold air. When this air comes into contact with a cold surface (windows, steel frame, hull) and cools, condensation forms.

Cooking or boiling water produces water vapour. Burning gas produces water vapour. Breathing produces a lot of water vapour.

If you want to live on the boat you have to either reduce the water vapour production (stop breathing, cooking, etc), remove the water vapour in the air (dehumid or ventilation) or reduce the temp of the cabin (ventilation). Simple!

 

[Matt341]

Thanks everyone for all the replies. The advice is excellent.

At the moment we have a 2kw convector heater that we keep set on a low thermostat to keep the cabin at a comfortable temperature but also ensure that it is stable, so not boiling one minute and cold the next.

My only concern with this type of heating is that the air isn't circulated as it has no fan. Most of the liveaboards in the marina have diesel blown air heaters so I expect that hot air heating helps with the condensation, if so, would a fan heater help reduce the condensation?

Just did a quick search on the Ikea website and have found the mentioned slats for around £10. I remember back in my caravanning days that there were thin ply boards fixed to the side of the wallboard to create an air pocket between the bed and side of the van. I also remember that the bed bases were slatted to ensure air circulation. Is it just a case of laying these slats between the cushion and bed bases? Obviously they may need to be cut to the shape of the V.

We always leave the bow hatch on vent to ensure air flow but the only problem is when its raining it can sometimes blow in. Maybe a small cover could be made.

I think im definitely going to consider the dehumidifier route. It will need to be fairly compact though so that it can fit in the bottom of the wardrobe.

Thanks again to everyone, please keep the advice coming.

Ian

 

[robertj]

Invest in solar vents the type with battery fitted
or computer fans are good apparently, warm air heating (eberspacher)
underneath the bunk cushions put slats, Ikea do them at a fraction of the cost of chandlers.
These are not myideas but read from this forum.
Being in Cornwall the wettest place in the world, the best boat for having no condensation probs is a sadler 26/29/34. Tho not as nice down below as a westerly.

Hope this helps
Bob

 

[robertj]

Sorry, it's been covered I missed the previous post

 

[Poignard]

We prop open the forehatch a bit and partly open the companionway sliding hatch. That way you get a through draft.

You will sleep better with the fresh air entering your lungs and, in the morning, you can have a bracing swim in the sea to set you up for the day.

 

[PCUK]

Foam backed cord carpet about a £1 a metre under the cushions will stop condensation there. Solar vents with internal battery to allow continual night time running will reduce overnight condensation. Fit general deck/roof ventilators in every cabin. Use the same corded carpet on hull sides to stop condensation there. Double glaze windows with perspex panels and draught excluder tape to dramatically reduce glass borne condensation.

 

[Bloater]

As most people have said: ventilation is the answer. The only problem is that when you open a window then it can get cold!

Using ANY heater to heat the air inside the boat will always make things worse... you are simply heating the warm damp air which turns it into warmer damp air (which can hold even more water and this will eventualy condense out on anything that is below the dew point such as the window frames).

The solution is to use external air and heat that up, this takes cold damp air (which can't hold much water) and turns this into warm dry air. This is the principle by which most diesel fired heaters use (providing that they don't recirculate, which is just wrong).

If you haven't got diesel heating which warms up the outside air then the next best alternative is ventilation. You need to bring in the cold air from outside that when heated becomes dry. Every now and again it is a good idea to open all the doors and hatches for a few minutes to change the air. Get rid of that hot damp air and change it for cold damp air, then heat it up and throw it away again.

A dehumidifier is a good solution, the downside is that it requires mains power and won't be silent (but then neither is diesel heating).

Those crystal things only work when they have been recharged by baking in an oven and therefore they have their drawbacks. They can't hold that much water and are therefore not really suitable for a boat that is occupied.

Sorry for the long reply - I hope this helps.

 

[stuhaynes]

Curing condensation

Thanks everyone for all the replies. The advice is excellent.

At the moment we have a 2kw convector heater that we keep set on a low thermostat to keep the cabin at a comfortable temperature but also ensure that it is stable, so not boiling one minute and cold the next.

My only concern with this type of heating is that the air isn't circulated as it has no fan. Most of the liveaboards in the marina have diesel blown air heaters so I expect that hot air heating helps with the condensation, if so, would a fan heater help reduce the condensation?

Just did a quick search on the Ikea website and have found the mentioned slats for around £10. I remember back in my caravanning days that there were thin ply boards fixed to the side of the wallboard to create an air pocket between the bed and side of the van. I also remember that the bed bases were slatted to ensure air circulation. Is it just a case of laying these slats between the cushion and bed bases? Obviously they may need to be cut to the shape of the V.

We always leave the bow hatch on vent to ensure air flow but the only problem is when its raining it can sometimes blow in. Maybe a small cover could be made.

I think im definitely going to consider the dehumidifier route. It will need to be fairly compact though so that it can fit in the bottom of the wardrobe.

Thanks again to everyone, please keep the advice coming.

Ian

We we first moved onto our boat in September 2001 all we had for heating was an old gas fire. I was burning a 13kg propane bottle every week, and the boat was swimming with condensation. Everything on board was wet through. The following spring I installed a log burner, end of problem. It's not an answer for everyone though.

If a solid fuel stove is out of the question I would suggest that either an Eberspacher or Webasto hot air system would be your best bet. You will still need to provide ventilation regardless of what you use.

An electric fan heater may be a stop gap, but not much cop in winter. We have one that we turn on if the fire's not coping, but this only happens when the temperature drops to -7C or less. Our record level this last winter was -12C and we definitely turned it on then! Our log burner is rated at about 4.5kw and we wouldn't be without it. It's got a 'soul', which diesel burners don't have.
Hope this helps

 

[Searush]

Slats cheaper at Ikea!

We have an ECS Solar Air vent in the forecabin hatch vent and vents in the washboards - now admittedly it doesn't work in the dark but we don't get any condensation (well a little on the windows this time of year but not enough to do anything about).

I recently bought one of those for the same purpose but have had second thoughts about fitting it after another person reported his shipping a wave first time out & getting stuffed. So does yours not get waves, or does it cope with them? Or have you not yet left the marina with it?

 

[gary3029]

I spend most weekends on my boat all year round. I have a charcoal heater which I keep in all night and a diesel heater which comes on early in a morning so the boat is nice and warm for when I get up. Condensation is minimal and I put this down to good ventilation and a heat source. This winter had many a warm nights sleep where I have had to break ice off the cover when I got outside.

 

[efitz]

Do people normally leave eperspachers running all night? Is this ok from a safety perspective? I've only ever run it for a couple of hours and only while on board and before bedtime. Then again I only have bog standard controls - no timer.