condensation

Jamesuk said:
I read that someone wired up a couple of 12volt computer fans on the vents pushing air out. Battery drain is minimal and they work :-)

Air circulation is key.
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Air circulation can prevent or reduce condensation but if you are pushing air out, you are also pulling air in. Depending on the temp & RH of the incoming air and on the effectiveness of ones bedding and indeed ones personal tolererance, air circulation may suffice but I think, there comes a point when it is better to close the vents and de-humidfy. 1 or 2 days of cold/damp may not be too much of a problem but I find that I will slowly loose condition after that.

I also suspect that a de-humidifer dries out the interstitial areas of a boat's fabric more effectively than just relying on air-circulation.
 
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stu9000 said:
My sleeping bag is three season and rated to minus two!
It was flippin' cold though. A bit uncomfortable on board, even for me.
--there is an en13537 standard for s/bags----the lowest temperature rating that manufacturers like to quote will not give you a good nights sleep ----it should stop you getting hyperthermia ----a s/bag rating to -2c will probably only give you a comfortable nights sleep at +6-8c----trust me i know what i am talking about ----i was camping on jura a month ago with all the tent vents wide open and no condensation----regards lenten
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Jamesuk said:
I read that someone wired up a couple of 12volt computer fans on the vents pushing air out. Battery drain is minimal and they work :-)

Air circulation is key.
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I do have a computer fan on one vent, but they are not very powerful and IMO wouldn't do a lot to disperse humidity from living aboard with heating in winter - when I use a small dehumidifier at night. As capnsensible says, it's a great boon - without it, there is a lot of condensation around even with the hatch well ajar.
 
capnsensible said:
Dehumidifiers are great and improve your quality of life enormously. I've got them on all my yachts.

Trust me, I've been living on board for 18 years and know what I'm talking about. :cool:
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No they're pointless unless you seal the boat up and stop outside air entering, in which case you'll suffocate. In normal use they produce lots of water which makes you think they're drying the air. In reality you are like King Canute constantly trying to hold the water back as more enters the boat through the vents.
According to the instruments, the humidity on my boat today is 42%, about right for comfort. Anything less would become a health hazard so, even if it was practical, why would I want to dehumidify? I and probably the OP are in the UK, not the Tropics.
 
ArthurJStoatfondler said:
No they're pointless unless you seal the boat up and stop outside air entering, in which case you'll suffocate. In normal use they produce lots of water which makes you think they're drying the air. In reality you are like King Canute constantly trying to hold the water back as more enters the boat through the vents.
According to the instruments, the humidity on my boat today is 42%, about right for comfort. Anything less would become a health hazard so, even if it was practical, why would I want to dehumidify? I and probably the OP are in the UK, not the Tropics.
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By closing all hatches and dorade vents and without any further sealing, running a dehumidifier dramatically reduces condensation in our fore-cabin and dampness in our bedding. I don't dispute that moist air enters through the crackage that remains but the net effect of closing vents and running our dehumidifier is without question, a drier and warmer boat.
 
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stu9000 said:
Hi

I slept in the forecabin of my Jag 27 a few weeks ago.
Bloomin' freezing so I shoved socks into the vents.
When I woke in the morning there was a lot of condensation on the roof lining.

As the weather warms up it will become less of an issue. But I will also have crew on board.

When I was a kid my Dad used to hang a condensation gizmo up.
It had crystals (that I think could be reused) and there was a drip tray that would hold a good couple of cups of water.
Not surprising when you have 5 people and a dog on a caprice 19!

Looking online I could not find anything that exactly matched my childhood experience but there were two non electrical types that stood out.


Non reusable crystals
http://www.amazon.co.uk/KONTROL-Oce...&qid=1427998944&sr=8-4&keywords=moisture+trap

gel type that can be recharged
http://www.amazon.co.uk/Rechargeabl...667&sr=8-8&keywords=non+electric+dehumidifier

Any thoughts or suggestions?

Thanks
S
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If you've got that much condensation on the headlining have you checked under the mattress?

On our Med boat the mattresses are soaking wet underneath in winter and we have to prop them up every day to air or they go mouldy.

I'm taking a roll of DryMat out with me in two weeks to see if that cures the problem.

Richard
 
My modern boat is not badly affected by condensation, except on the metal surrounds of the windows and hatches. This wouldn't matter if it were not for the fact that one source of dripping water is just above my head. I don't fancy trying to sleep with a dehumidifier running all night, even if I could be bothered to cart the thing around with us.
 
ArthurJStoatfondler said:
No they're pointless unless you seal the boat up and stop outside air entering, in which case you'll suffocate. In normal use they produce lots of water which makes you think they're drying the air. In reality you are like King Canute constantly trying to hold the water back as more enters the boat through the vents.
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Obligatory mention of Canute's actual intentions aside (seems the swear filter *s out the other spelling of his name)....

In winter, without the dehumidifier on I invariably get woken up by drips from the window above our bunk, there is condensation hanging on the main hatch in the aft cabin and there is condensation on the headlining. Leaving the dehumidifier on overnight, no dips, very minimal condensation, and the best part of a litre of water in the dehumidifier.. I'd hardly call Brighton in winter the tropics. A dehumidifier improves my quality of life enormously.
 
Ian_Rob said:
.....but if the boat is too cold because of that ventilation and the vents have to be closed, a dehumidifier will very much reduce the condensation and eliminate the feeling of dampness that you get in bedding.

At the beginning and end of the season, we run a dehumidifier from early evening and throughout the night and, without any heating, remain warm and condensation free even under a duvet.
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Our dehumidifier actually raises the temp about 2C whilst it is hard at work keeping the boat VERY dry. Wouldn't be without it
 
Could the pro-humidifier camp recommend which one to get?

The OP said for a 27 foot boat.

What is the best small, silent, cheapish mains unit?
 
ArthurJStoatfondler said:
No they're pointless unless you seal the boat up and stop outside air entering, in which case you'll suffocate. In normal use they produce lots of water which makes you think they're drying the air. In reality you are like King Canute constantly trying to hold the water back as more enters the boat through the vents.
According to the instruments, the humidity on my boat today is 42%, about right for comfort. Anything less would become a health hazard so, even if it was practical, why would I want to dehumidify? I and probably the OP are in the UK, not the Tropics.
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But what is the temperature? About ambient I'd guess!
 
In my experience natural ventilation is for summer and dehumidifiers are for winter if you are living on board. In winter the dorade caps are fitted and the dehumidifier runs whilst we live on board at weekends. Boat stays dry. We can't maintain a nice warm dry environment without dehumidifiers when we are living and cooking on board in winter.
 
geem said:
... We can't maintain a nice warm dry environment without dehumidifiers when we are living and cooking on board in winter.
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We do, but we're aboard every day. Perhaps your boat is left unheated during the week which would mean that it's damp when you arrive on board at the weekend, so you dehumidify it.
Heating and ventilation is all that's required to keep it dry. The same as a house.
 
Thanks for all the suggestions.

Dehumidifiers wont work for me. I have used them at home to dry out plaster etc and can see that they would suck out damp from wall furnishings and cushions. But my Jag 27 is on a mooring and has no shore power. So I cant spare the leccy.

Point taken about the quoted minus 2 on my 3 season sleeping bag. I did read the small print about this standard staving off hypothermia rather than being comfortable.
That said, I have slept on snowy ground quite comfortably with this bag. Wearing a hat is also good advice. My wise ol' pa always says "you lose 80% of your body heat through your head" and he is dead right.

The boat is pretty sweet smelling. The previous owners all looked after her beautifully. I was silly to block the vents and want to make sure she doesn't get musty.
The comment about dampness under cushions reminds me that you can get vent matting that allows air to circulate underneath cushions.
This stuff costs a fortune...
http://www.shipshapebedding.co.uk/Dry-Mat_Anti_Condensation_Layer.php?li=dry-mat
...but I am sure I could come up with a cheaper option if I felt strongly about it.

My headlining is the smooth wipable type and is in good condition. No way am I messing with carpet.

My washboards do have some breather holes in.
Perhaps not enough for when a family of five are on board.
Cracking the forehatch and main hatch a tad would help a lot, especially when it the ambient temp is less freeeeeezzzzziinng!

I like the idea of using a pc fan to gently suck air through the boat. I might add a new vent and mount something on the inside that would pull air through the boat from the vents for'ad.

Long term, Id like to get a vented charcoal burner or similar. I have received good advice in other threads but this is proving more costly and tricker than I thought.

So I will focus on ventilation for now.
I still might explore the £5 disposable crystal dehumidifier though, perhaps keeping them for the inevitable wet bank holiday weekend family event. It is no doubt "king canute" but if it helps to prevent a mutiny then it is money well spent.

Dont tell anyone (especially SWIMBO) but I have very fond memories of these kinds of wet weekends.
A few games of killer family scrabble. Standing at the hatch watching the grey sky and water dripping off the spray hood. Just reading and hanging out. Hearing the drum of rain on the coach roof and feeling cozy-comfy-self-sufficient inside the cabin. I cant wait!

Cheers all

S
 
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