A New Though for Mats and Condensation Barriers

[Hudson Force]

We've added a new foam mat barrier under our V-berth,- not a lattice for venting air like Dri-Dek or those Foli springs, but a significant insulation barrier.

We saw these first in our grandson's play room as interlocking foam tiles at about one square foot each. They are brightly colored children's tiles containing the letters of the alphabet and sold for less than $14 for 25 square feet at many large discount stores.

Inexpensive and easily cut to fit.

[weavis]

all that matters is : Does it work?

[Hudson Force]

I've just added it today, but time will tell. I do know that the foam "cozy" that my cold beer can sits in doesn't offer any ventilation, but the outside grip is never damp! I should admit that I'm never presenting much of a true test sitting in Florida winter weather! I doubt if I ever have more than a 10*C to 12*C difference between the water temperature and my boat interior.

[Tayana42]

This is the same approach sailorchick wrote about. Hope it works well for both of you.

[Leo Ticheli]

We use this stuff on our boat and it works; no condensation under the mattresses or cushions. HyperVent Marine - Putting An End To Condensation You may be able to find it cheaper elsewhere.

We also added a layer of duct insulation around the A/C ducts, which greatly reduced the condensation.

Fair winds,
Leo

[thinwater]

There are 2 things that cause condensation, and the cures are different. Perhaps this is why folks argue over who is right (other than being sailors!).

Cold surface below. In the winter the fiberglass gets cold, and insulating it (sealed to the surface) stops the sweating. Typically they are running heat, so the cabin is dry.

High humidity. Sleep all night and moisture moves from your back, through the mattress to the deck. With nowhere to go... the mattress gets wet. In this case insulation won't help, since the deck is the same temperatures as the air, but moving air helps.

Two separate solutions to two different problems.

[Hudson Force]

Originally Posted by thinwater

There are 2 things that cause condensation......................

...Cold surface below..............

...High humidity......................

........Two separate solutions to two different problems.

I can accept this explanation from thinwater, but I'm only concerned with the temperature gradient between the opposite sides of my hull.
My only events of some moisture formed by condensation are at the outer edges of my mattress where it is adjacent to the colder hull. I often experience high humidity in Florida, but my only condensation problems coincide with colder air and water outside my hull.

I'm not disregarding thinwater's wise explanation, 'just focusing on my purpose. Those with relatively high humidity within their boats probably need to address ventilation.

[basssears]

Originally Posted by Leo Ticheli

We use this stuff on our boat and it works; no condensation under the mattresses or cushions. HyperVent Marine - Putting An End To Condensation You may be able to find it cheaper elsewhere.

+1 for Hypervent, we've had great success with it.

[skipgundlach]

Originally Posted by basssears

+1 for Hypervent, we've had great success with it.

Plus 2; we have a predecessor (scrim on both sides, black mesh), and have ordered another 7' for our salon bench.

Sitting where I am now, on the settee around the table, I got up to reorient the cushion cover which had rotated on the foam.

Despite our Pfifertex mesh bottoms, there was signifcant moisture below where I was sitting, let alone sleeping for 8 hours.

Time for some more Hypervent. FWIW, on the East coast at least, we found Defender to be the most affordable when shipping to S FL...

[Tayana42]

Originally Posted by basssears

+1 for Hypervent, we've had great success with it.

I use Hypervent too with good success. But it is expensive compared with the mats discussed in this thread. If you want to wrap the sides of the hull up to the level of the mattress the mats would be softer with no sharp edges to snag sheets.

[Buckanear Bill]

I have beed to a brazillion boat shows, but don't recall ever seeing it. Thanks for enlightening me. I'm already thinking of many uses for it. Maybe use it under hatch covers for a little additional insulation? It isn't cheap, but hey, any time something is labeled for boats it automatically costs B.O.A.T. dollars.

[skipgundlach]

Originally Posted by Hudson Force

We've added a new foam mat barrier under our V-berth,- not a lattice for venting air like Dri-Dek or those Foli springs, but a significant insulation barrier.

We saw these first in our grandson's play room as interlocking foam tiles at about one square foot each. They are brightly colored children's tiles containing the letters of the alphabet and sold for less than $14 for 25 square feet at many large discount stores.

Inexpensive and easily cut to fit.

Do you have a product number - and, while it may keep the high latitude cold water temp from hitting the bottom of the mattress, does it prevent condensation under the mattress?

I'm in very warm water/air temperatures, and the plywood base to the seat I mentioned is well away from the hull in both directions...

Warm and isolated hasn't prevented moisture from making it through 4" of foam and sunbrella...

[Hudson Force]

It's easy to see a great variety of these "alphabet play mats" by looking at Walmart, Target, Amazon, eBay, etc. for prices from $12 to $24 for about 25 square feet.

I can't tell anyone about how well they work as I just installed it under my V-berth yesterday. I'll be glad to report back with an evaluation after a month or two.

[Djarraluda]

Originally Posted by Hudson Force

I can accept this explanation from thinwater, but I'm only concerned with the temperature gradient between the opposite sides of my hull.
My only events of some moisture formed by condensation are at the outer edges of my mattress where it is adjacent to the colder hull. I often experience high humidity in Florida, but my only condensation problems coincide with colder air and water outside my hull.

I'm not disregarding thinwater's wise explanation, 'just focusing on my purpose. Those with relatively high humidity within their boats probably need to address ventilation.

To get a little technical.....
Air will hold more moisture when warm than cold, which is why we refer to "relative humidity" when talking psychometrics. The moisture is an absolute value in the air, but its percentage will vary with the temperature.
To get condensation, the air is cooled to the point where we reach close to 100% humidity, the air can not hold the moisture anymore, so it condenses out. 100% humidity is also known as the Dew Point!

Purpose of this explanation is to introduce how insulation works. It insulates a surface and thus changes the surface temperature. To stop condensation, of course it needs to have a vapour barrier on the exposed side, otherwise the moist air penetrates. If you want to start calculating things, we can define the insulation values necessary for different temperatures to ensure the moist air is never exposed to a surface that is below the dew-point temperature. When that is done, we avoid condensation.
Roger

[first wind]

Originally Posted by Hudson Force

I can accept this explanation from thinwater, but I'm only concerned with the temperature gradient between the opposite sides of my hull.
My only events of some moisture formed by condensation are at the outer edges of my mattress where it is adjacent to the colder hull. I often experience high humidity in Florida, but my only condensation problems coincide with colder air and water outside my hull.

I'm not disregarding thinwater's wise explanation, 'just focusing on my purpose. Those with relatively high humidity within their boats probably need to address ventilation.

you could insulate. i insulated the inside of my boat with armaflex. 1/2" thick on the hull and 1/4" thick on the underside of the deck in the v-berth (the only place i had minor trouble with condensation on the 'ceiling'). it's about 7.50 a square foot if you have to pay for it but, it's excellent. it holds the heat in and keeps the cold out. it's moisture and mildew proof. you use spray adhesive to apply it. it's very dense and you can use spray adhesive to put vinyl or other materials on it as a wall covering without having to epoxy stringers on the inside of the fiberglass. i can't recommend it enough.

i got mine for free but, if i had to pay for it, i would.

for my v-berth, i lined the hull below the berth with armaflex and then i installed a nice wooden duct register on the side of the upraised v-berth to allow warm air to circulate between the insulated hull and the surface the mattress is on.