Moisture control under v-berth mattress

C

C-Wolfe

Member
On my last couple outing of the year (it was rainy and cold), I ended up with a good amount of moisture under the v-berth mattress in the morning. I was able to dry it by raising the mattress but its not very convenient as I store bulky thing in there during daytime .
I just received a sample of the Den-Dry from Ravenwolf Marine, It look nice but seem a bit to easy to crush if you kneel on it and will potentially reduce its effectiveness. Anyone have experience with this product? Any other recommendation that I should consider. I want to do this right but also have a limited budget for the boat right now. Thanks for any input.
 
The rooftop tent and van camping communities offer lots of resources in condensation control and mitigation. An under-mattress condensation mat is pretty typically indicated, together with ventilation (make-up and exhaust). That community also lives in the 12v world, so check them out.

Best, Mike
 
On our earlier SE Alaska extended cruises we had extreme condensation at times, causing our bedding in the v birth to be soaked. We solved this with Hypervent. I doubt there is still anything better for bedding moisture protection in the v birth.

Jay
 
Hypervent is the best value for the buck. There are other similar products, but generally are more expensive and do not work as well. I would extend the Hypervent up the sides of the hull on the edges of the mattress--the line the V Berth area with either back packing pads (cheap at Wal Mart" or "fish blanket" (A foam which is put between layers of fish as it is is iced in holds. We lined the entire hull of our Cal 46 with fish blanket--and it "Cured" our condensation issue. which is available in hardware stores in AK and PNW.
 
I did look into the Hypervent, I need to contact them as they do not offer shipping quote to Alaska.

Line the V Berth area with either back packing pads (cheap at Wal Mart" or "fish blanket" (A foam which is put between layers of fish as it is is iced in holds.

Bob, are you talking about side and roof or under the mattress?

Thanks
 
Line the V Berth area with either back packing pads (cheap at Wal Mart" or "fish blanket" (A foam which is put between layers of fish as it is is iced in holds.

Bob, are you talking about side and roof or under the mattress?
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C-Wolfe I am suggesting That you use the pads on the sides of the hull--If you want on the ceiling--the Fish blanket would look OK, but the back packing pads are usually green or blue...

On our boat, used in the lower 48, we did put the pads under the mattress also--A thin pad might help distribute the weight, if you put it over the Den-Dry. Your knee weight is probably more focused than the material you put on top of the mattress. If I was dong the top, I would also make a several layer plug to put on the inside of the hatch. In our RV's we have 3" thick pieces we put into the fan vents when in cold weather.
 
Thanks Bob, I like the idea if nothing els but for the hatch since it is collecting a good amount of moisture compare to anything els around. For the side of the hull, am I crazy to think of using floating floor underlayment? It's very thin, waterproof, ok insulation value and dirt cheap. They make synthetic cork which will look good
 
Like Bob says, the pads are cheap & work really well for the sides. They are very easy to cut to fit. Mine are the blue. The Hypervent keeps the moisture off the mattress bottom & the pads keep it from being transferred to the mattress sides & the blankets. When we have heavy condensation it comes from the v birth top & then down behind the pads with the combination pads & Hypervent protecting the bedding. Very little moisture drips from the v birth ceiling & the pads also stop your body & things stored from picking up the moisture, when making contact with the sides in the v birth.

During extreme condensation periods we have had to lift up all the bedding plus the Hypervent & wipe up the pooled water underneath. This is a small thing compared to drying out all the bedding, while on an extended cruise.

Jay
 
I went for a long time with no cabin/V-birth moisture, but when I changed sleeping bags it started to be an issue. I looked at multiple options, and tried the blue "Yoga" pads first, the thicker ones. Helped but I was still getting moisture between the pad and the gelcoat, bottom and sides.

The Hypervent, I liked for it's lightness. Very airy, but also some very stiff points and I was concerned that it would leave scratch markings on the gelcoat over time. I went with a pad from American Floor Mats:

Vinyl Mesh Entrance Mats are constructed of an extruded vinyl in a random loop pattern. This mat traps dirt and moisture and helps promote a safe, non-slip floor.
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https://www.americanfloormats.com/vinyl ... ance-mats/

American Floor Mats, 1-800-762-9010
152 Rollins Ave #102
Rockville, MD 20852


It is not the cheapest, but nor is it expensive, and there are a dozen colors to pick from, as well as multiple sizes. It is easy to cut with a pair of trauma scissors, or probably good shop or kitchen shears too.

The vinyl-mesh-entrance mat, and at that page you can select the "No backing" option. It is considerably softer than Hypervent, but thick and stiff enough to not compress when laying on it (obviously under the V-Birth mattress pad) and it is easy to cut. It has a flattened surface and a not so flat one. I put the flat one on top against the mattress, so the one on the gel coats would be a bit softer there. I also cut and fit the pieces to run up the sides about 6 inches to keep the mattress and bedding from touching the cabin sides and allow air flow completely throughout under the mattress pad. No more moisture. I thought the Unbacked version would be easier to clean, hang it up and hose through it, or on the boat, roll it up and put it in the cockpit and sweep up from under it and then put the roll back in. This part is for the section I have for the hall way floor "carpet". Easy on bare feet.

Harvey
SleepyC :moon

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crowleykirk":2r4igpqb said:
https://www.mattressinsider.com/mattress-condensation-prevention.html

In our camper and it works amazing. No more mold growth. I haven't added it to the boat yet.
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That is Hypervent.

HYPERVENT AIRE-FLOW™ MOISTURE BARRIER

Harvey
SleepyC :moon

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I had the drippy cave, dampness under the mattress syndrome and solved it by adding Vetus round portholes on the port and starboard wall of the V-berth and elevating the mattress by a adding 1/2" x 3/4" cedar slats every 4" under the mattress to allow some airflow. I open the portholes and hatch (as long as it is not raining too hard) when I sleep. Cabin windows still steam up but running the Wallas in the morning clears that.
 
We used this product under our vee berth on our sailboat and under the settee also. If you kneel right on the product it will compact it some. It worked really well for us and when it had the foam on top, it did not crush when crawling in. My wife said it was fairly easy to install. It stopped the condensation under the mattress and we used the boat in the winter time, spending several days onboard when the temp was in the lower 40's. When we were not on the boat we do run a small dehumidifier that sits in the sink and keeps some air flow going. We received good customer service from them too.
 
Another who used the Hypervent under the mattress, the foam backpacker pads on the sides of the hull - from the bottom edge of the mattress to the shelf (in the CD-25), and a solar vent cut into the v-berth hatch. The foam on the sides was also nice if you happened to "back into" the fiberglass side. :disgust

We spent up to 6 months at a time onboard, and the above made a significant difference for not a lot of bucks.

Also, if it isn't too cold, putting the front hatch on the latches that keep it open just a crack is another way to help. And, running the Wallas (if you have one).
 
Boater Rob":1k2128kd said:
We used this product under our vee berth on our sailboat and under the settee also. If you kneel right on the product it will compact it some. It worked really well for us and when it had the foam on top, it did not crush when crawling in. My wife said it was fairly easy to install. It stopped the condensation under the mattress and we used the boat in the winter time, spending several days onboard when the temp was in the lower 40's. When we were not on the boat we do run a small dehumidifier that sits in the sink and keeps some air flow going. We received good customer service from them too.
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Boater Bob, I had to look several times, --> Dry-Den. Is that what you used? How, or which product?

Jim, I have never run the Wallas over night. Didn't want to run the battery too low, but I do run the CPAP (Priorities :roll:
and it moves air continually so I think that helps. The forward hatch is always open at least to where the latches catch. Depends if I'm at anchor or at a dock.

Harvey
SleepyC :moon

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Another vote for Hypervent. We lived aboard fulltime for 2 years on two different boats (30’ houseboat and a 35’ yacht) and used it both times to great success.
 
I might mention that "Thataway" C Dory 25, had the Nico Solar vents in the foreword hatch, and over the top of the cabin all of the way aft. There was a passive Nico vent over the area under the splash well, with extra louvered vents in the access hatches in the aft end of the cockit. That extra ventilation and air flow also helps.
 
We had the same problem with moisture under the mattress and in the cabin and berth overall. Being from bone dry Alberta we are probably hyper sensitive to the moisture when we are on the coast. We boat mostly off Vancouver Island, but have had our boat in the water from the Yukon to Lake Powell. We tend to attract bad weather when we are on the water, even sitting out a three day downpour on Lake Powell. I find the boat seems to get wetter when you are just sitting that cruising, probably because of the lack of ventilation that you get when the boat is moving. Solving the moisture under the mattress was just part of our moisture control strategy and sitting our storms in the Broughton's and Nootka Sound this summer proved that we were on the right track. We lined the entire berth area and the cabin ceiling with a marine headliner fabric. This product was glued on and it very complicated to install, but it does work well. We put this under the mattress as well and it has helped keep the mattress drier. But what I think is more important was to increase the heating and ventilation in the boat. We have a Wallace, which works ok to heat the cabin, but in an extended storm swinging on the hook, it was not enough. So I added a Wabatso diesel heater with a return air hose pulling heated air into the v-berth area and this works very well. The forced air moves a lot of air throughout the cabin. Also a solar powered vent was added in the cabin which helps to move more air out of the cabin. We also changed most of our bedding and sheets from cotton to polyester which does not hold the moisture as much. The result being that we didn't have to crawl into a damp feeling bed in the evening. Overall the system works well, but it is still good to lift the mattress up and open the hatches and windows when the sun comes out to dry things out. We split our horseshoe shaped mattress in two so that it is easier to lift and remove. Is our boats interior as dry as it is in Alberta? No, but it is more comfortable and a dripping ceiling is a thing of the past.
 
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