Damp

[Sid Charles]

Well I have been re-fitting this boat for nearly two years and during the winter months I have encountered the cold, but yesterday and today for the first time I encountered actual damp, well wetness so bad my paperwork was soggy. The boat is insulated really well and fully lined, the windows are all sealed and no doors open, it looks pretty serious! could it be that on Sunday I had the boat warm and the sun also helped, and overnight the frost attacked, just how does it all work? it's something new to me, will damp and condensation be my enemy forever? are there any tips? can't turn picture again

Edited December 1 by Sid Charles

[David Mack]

Any heating in the boat? Ventilation?Any water in the cabin bilges?

We're you producing water vapour from cooking/showers/breathing?

[Sid Charles]

David, the boat is bone dry in bilges I took it down to bare metal, no water on board at all yet

[Arthur Marshall]

Doesn't anything left outside in wet weather unless it's hermetically sealed?

I prefer to leave mine with plenty of ventilation, it seems to dry out better.

[b00ke23]

53 minutes ago, Sid Charles said:

can't turn picture again

 

Turned it for ya!

 

[Tony Brooks]

I can't see any signs of permeant high level vents, so goodness knows if there are any low level ones. 

 

Warm air holds more moisture than cold air, and someone working in a boat, burning gas, and cooling will make plenty of vapour. If there is insufficient ventilation then as the air cools it will give up its moisture, usually on the coldest surfaces. Ventilation will help exchange the warm moist inside air with cooler, dryer outside air. 

 

Unless the rain is driving, try opening the window hoppers.

 

 

[Sid Charles]

Tony

 

You may have a point, I sealed some vents and the Mushrooms are still off the roof so maybe that is holding the warm air which then cools to water. Hmmmmm

[Tony Brooks]

53 minutes ago, Sid Charles said:

Tony

 

You may have a point, I sealed some vents and the Mushrooms are still off the roof so maybe that is holding the warm air which then cools to water. Hmmmmm

 

Before you start cutting the head lining boards, try leaving a couple of hoppers open and see if it helps, if it does then recut the roof vent holes, but you will also need lower level vents so hot air can rise up through the vents and cold air flow in lower down to replace it.

[Chris John]

Have a look at this. There is also a part 2 

 

[MtB]

3 hours ago, Tony Brooks said:

I can't see any signs of permeant high level vents, so goodness knows if there are any low level ones. 

 

 

I'm not sure how either would help in an unheated boat on a day like today, when the RH must have been close to 100% all night and all day. The air inside the boat will have slowly changed, vents or not, and the interior RH built up to the same as outside I'd have thought.

 

 

 

 

[Tony Brooks]

10 minutes ago, MtB said:

 

I'm not sure how either would help in an unheated boat on a day like today, when the RH must have been close to 100% all night and all day. The air inside the boat will have slowly changed, vents or not, and the interior RH built up to the same as outside I'd have thought.

 

 

 

 

 

I got the impression that the OP had been working in it with it all shut up.

[Gybe Ho]

3 hours ago, Sid Charles said:

Tony

 

You may have a point, I sealed some vents and the Mushrooms are still off the roof so maybe that is holding the warm air which then cools to water. Hmmmmm

 

The humidity will seesaw up and down day & night as the boat cools and warms. You say there is no water on the boat but there will be a soggy human in the boat a times venting off moisture with each breath.

 

Given that there is little air exchange a dehumidifier would help until you reintroduce vents later in the build. For less than £10 you could buy a battery powered temp/humidity display & logger to calibrate the problem, I bought one for my boat Govee is the brand on Amazon, it logs data and can do graphs on a mobile phone via bluetooth.

 

Another option would be to experiment with a chemical dehumidifier that will capture about 1/2 liter per sachet. My local hypermarket sells these for under £20.

[Ronaldo47]

Just breathing out produces plenty of water vapour, which you can clearly see when outside on a frosty day, and as condensation on the windows of a car if you sit in it on a cold day with the windows closed and no heater or fan operating. It would be the same in an unventilated boat. 

Edited December 2 by Ronaldo47
Typos

[blackrose]

Where's the dampness or condensation accumulating exactly? I can't see from your picture. 

 

As others have said, ventilation is important.

 

Apart from lack of ventilation one other factor which hasn't been mentioned is that when you first return to a cold boat and light the stove or switch on a diesel heater, because the air inside the boat heats up much faster than the dense, solid objects in the boat, the moisture in the warm air is drawn to the cold objects and condenses on them. If you come and go every week or so and the boat goes through several cycles of heating and cooling the moisture can accumulate.

 

I've noticed this especially in low level cupboards which had a load of tools inside. There was so much water in them I thought I had a leak! Once I emptied the bottom of those cupboards and put some small vents in the doors the problem went away.

Edited December 2 by blackrose