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The majority of broads boats were presumed to be used in the hire season,  no point in the yards spending money on insulation.

When they pass into private hands they are more likely to be used out of season.

Partial insulation can cause problems by concentrating condensation formation on uninsulated areas and in extreme cases it can form on areas that were not previously affected,  such as under beds and stored leather items.

The most effective cure for condensation is ventilation and constant moderate heat.

Sorry to ramble but this time of year I spend half my life talking to people about it.  :default_biggrin:

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I did the bow V berth area as that is where we sleep, I used 1/2" celotex where I could and the foiled bubblewrap stuff where it needed to be flexible, I did foil tape all the edges so the condensation didn't just collect behind it.

We did get water running down the vinyl panels in the berth in winter but that has gone now, it will be there somewhere but not in my bedding.

I'd like to do my cabin but not going to take down the old vinyl unless I'm replacing and that will have to wait due to lack of bearsedness. (there's a new word for you, feel free to use it but royalties are payable in beer!)

The airmat stuff is good under mattresses but not cheap, it gives a bit of air flow under them.

Windows are a lost cause. but a karcher window vac is great only downside is you can't use it upside down for steep angled screens or the water comes through the motor, I also made up a lead so it could charge via a usb socket instead of being reliant on mains for charging.

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Thoughts from a wooden saily owner:

Cover the boat, allow ventilation. You have insulated it without the trauma of taking down the vinyl lining. (I have done a re-line on GRP argh) That's why so many of the sailies have 'overcoats' . I did this with our GRP one when we had it and that worked too.

Under the mattresses, I use a double layer of IKEA rug underlay, the mesh one , and have never had an issue, this worked with GRP too. 

Finally, don't mess with winter, take out your fabrics and put in damp crystals. Roys DIY are cheap and cheerful.

we used to lift out every other year with GRP but annually with wood.

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1 hour ago, vanessan said:

That’s a great idea, could you share your method for this Smoggy?

Buy a spare charger off fleabay, cheap chinese junk is fine as you wont use the power adaptor, cut the lead and graft to an unused usb cable, black to black, red to black with pale white tracer.

I did it as an experiment as the charger says 5.5v output, I guessed it would be dropped to something like 3.7v in the vac so gave it a go.

The green light flashes while charging and stays on when full, my usb socket shows amps drawn and drops to 0 when charged so charging regulation must be inside vac, I stayed on board and checked temperaturee first time and all was fine.


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Onboard Independence the best trick to cure damp has been to remove moisture from the air.  I was going to invest in a dehumidifier but instead just bought more tube heaters - just one 135w heater left on in the forward cabin has removed the condensation that would form on the wood panels, and has also taken away that terrible 'damp feel' to cushions and carpets.  Despite their low power consumption, they will heat the air just enough - and as the air passes over the heated tubular surface it creates convection currents and that in turn causes a constant, slow movement of air.

Where I did still suffer dampness was under the foam mattress. I bought from Amazon some Dry-Mat which cost £55.00 for a double and has completely eradicated any dampness under the mattress. So good it has been I am getting another for the rear master cabin.


While nothing will beat a De-Humidifier in actually capturing moisture in the air, doing what I have has taken a cold and damp feeling space into a much dryer space. I have had no condensation issues or any dreaded mould/mildew appear.

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It is important to maintain ventilation when introducing a heat source if a dehumidifier is not used, the warmer the air,  the more moisture it will hold,  the air will lose the ability to hold moisture as it cools, such as coming into contact with windows or uninsulated panels  if the temperature drops.

When using crystals,  except when in  in a cupboard or closed area,  don't have ventilation as you will be drying the external air and not properly reducing  the internal  atmospheric moisture levels effectively

Hope this is useful.

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4 hours ago, LondonRascal said:

Onboard Independence the best trick to cure damp has been to remove moisture from the air.  I was going to invest in a dehumidifier but instead just bought more tube heaters - just one 135w heater left on in the forward cabin has removed the condensation that would form on the wood panels

Best option is heat and air movement as Dehums don't work best till the temp is over 14c, I have a oil heater in my man cave (insulated concrete section garage type build) which runs on a Saturday then a smart switch that turns the dehum on at 14c, this starts to pull the RH down and temp raises faster. The dehum is controlled on it's own stat till the temp drops to 13c then the smart switch turns off. I can monitor the temp and RH% on my phone. Tools and paperwork are kept ok in there.

I've been looking for a months at these Chinese heaters, the all in one in the red case to duct the air round better but I only have a 3" wooden section in the roof pitch to get the exhaust out of the shed.

Don't forget you don't need fancy test gear to test humidity, a cold can of beer from the fridge if it gets wet there's water in the air.

I keep going to put some smart items up which would work on boats via a key fob which i've tested, this could be wired inline and has 4 channels.

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A dehumidifier will work at over 5 degrees and will remove the same level of  moisture as one operating at a higher temperature but will cost slightly more to run.

In operation it will produce some heat as a by product. If you are heating the boat,  a dehumidifier set to 65% relative humidity will eliminate condensation for very little extra cost is it will turn on/off automatically.

I have used this set up for years and never have a damp/condensation issue,  the boat is dry and ready to go as soon as we arrive.

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