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What to use under mattress

Dec 19, 2006
Hunter 36 Punta Gorda
I know this has been talked about many time but a friend asked me what I do
and I do not use anything under my mattress but do use a memory foam topper and so what is the best thing to use with out spending
$$$$$$$$$ so any good ideas.


Jun 4, 2009
Pearson 530 Admiralty Bay, Bequia SVG
We use DriDeck under all the mattresses except ours in the aft cabin. Honestly, I don't know that it helps, but it makes me feel better to believe that air can circulate under the mattress.
Jan 6, 2010

I have never used anything under my cushions so, my question is why do you feel you need this?
If your having an issue with cushion sliding, I would suggest Home Depot or similar and just look for a rubber type non-skid matting material. I've seen examples that are interlocking also. You may only need to assemble & cut your shape to fit.



Sep 13, 2012
1979 Hunter Cherubini 30 Clemmons
My cushions have a vinyl bottom. Are you supposed to put something under your mattress?
Jan 6, 2010

If you don't have moisture problems & vinyl bottom , I do not see why pal.
If moisture, it comes into the cushion from the top.
Feb 10, 2004
Hunter 40.5 East Greenwich, RI
It is the moisture given off by your body that enters the mattress and exits the bottom. The supporting surface becomes wet and that is the issue. I would think that it would promote mold growth. Getting air to circulate should help to dry the moisture.
Jan 6, 2010

I'm still in the dark here pal. When sleeping aboard, I use two sheets. I can see if sleeping in hot humid weather yea, one can sweat but SEA was speaking of underneath the cushion.

But, with little additional info upfront as to what his question referred to, I'm not sure of what/why he is asking.
Maybe he will read this & give us a better explanation for his orig. question.

Jan 4, 2006
Hunter 310 West Vancouver, B.C.

If you don't have moisture problems & vinyl bottom , I do not see why pal.
If moisture, it comes into the cushion from the top.

Treat it like a house and install a vapour barrier on the warm side of the insulation (the mattress). Our mattresses came with a fine polyethylene sheet on the TOP of the foam, inside the mattress cover. We've removed the covers for cleaning and used dry cleaning bags as the vapour barrier when reassembled. The film is so fine it gets torn up when removed. Don't use anything thicker or you'll listen to it crincle all night. Never seen a trace of moisture under the mattresses. Total cost $0.00.
Nov 30, 2015
Hunter 1978 H30 Cherubini, Treman Marina, Ithaca, NY
so what is the best thing to use with out spending
$$$$$$$$$ so any good ideas.
I would think all that $$$$$$$$$ saved should go under the mattress? I think there is a dessicative function in $50 bills!
Mar 20, 2012
Cal 34-III, MacGregor 25 Salem, Oregon
the pads can help in some cases, but not all cases.
the mattress pad protector/ventilator is usually desired on boats that sweat and the moisture runs down the inside of the hull to soak into the mattress..... using one is an attempt at solving a symptom and saving the mattress from the real problem.

a wet bilge or leak is almost always the cause of a chronic problem, because the water is already in the boat, never leaves, but continually gets recycled as it evaporates and then condenses again.... the ventilation pads very rarely help in this case.

dry the bilge and keep it dry, and then add full time ventilation to the boat somehow.... this solves the problem in almost every case.

however, in warm humid environments, depending on the mattress thickness or material, when people are sleeping on it and if it lets moisture thru to the mattress deck, it may condensate, and a ventilation pad will help in this case

some boats have a carpet type stuff on the walls, which on a wet boat, can become horrendous with mildew/mold and saturation, but on a dry boat, I repeat on a dry boat, the covering offers benefits.
it offers a bit of insulation for sound and temperature, and, when there are people aboard sleeping/cooking/partying/living, the covering helps to prevent the natural condensation from forming on the hull interior and running down to the mattress and bedcovers.... what little condensate that may form is wicked away from the hull in the fibers and will airdry with the air movement within the boat due to the people moving about or a fan running..... but this evaporated moisture still needs to be ventilated from the boat, or it will accumulate and cause dampness in everything....

for those who want to have a ventilation pad under their mattress, the cheapest, yet fully functional is a product called foundation drain board. it can be found in different styles from different manufactures, and a piece big enough for a bed can usually be gotten for free from a contractor who pours concrete basement walls (its used as a ventilation pad on the outside of buried concrete walls to allow water to drain away and not stand against, and leak thru, the wall), and IIRC, I read somewhere a few years ago that the first type of this product was the where the ventilated mattress pad used on boats was born from.


Jan 22, 2008
Hunter 37-cutter Richmond CA
We have had a problem with moisture under the mattress. It never happened in the delta (30 degrees warmer, much drier) but was problematical in San Francisco Bay. It is also worse when we just spend 1 or 2 nights a week on board.
We solved it by placing the small plastic step stool for climbing up into the V-berth under the mattress when we leave the boat. This allows it to vent and the mildew problems have gone away.
A lot of the moisture in the mattress and bedding comes from the humans and is unavoidable. Ventilation takes care of the problem.
Dec 19, 2006
Hunter 36 Punta Gorda
Thanks everyone and as I said I don'the use anything and just helping a friend.
Jun 2, 2011
Hunter H33 Port Credit Harbour, ON.
I use the dimpled plastic material that is used on foundation walls. It solved the moisture problem. I also started to use it in all of the storage compartments that come in contact with the hull. Works well there as well. Pretty inexpensive but it usually comes in a big roll. May not be available where basements are not the norm though.
Jun 4, 2004
Hunter 410 Punta Gorda
When I bought my new custom mattress in Port Charlotte they recommended a thin sheet of open celled spongy material. I think it is 3/4" thick. They actually threw it on for nothing. I use to have moister under my mattress with the boat here in Florida where there is plenty of moisture. This material has eliminated the problem.
Jun 6, 2006
currently boatless wishing Harrington Harbor North, MD
If you are looking to keep the mattress foam dry sailrite recommends the foam be wrapped in plastic silk. Looks just like suran wrap but does not stick to itself. Wrap the foam in it, stick the shop vac in the seam and suck the air out and stick it in the mattress cover. Let the foam expand and you have moisture resistant foam. Sailrite has video where you can see how to do it. Id think that the bottom of the matress would not get wet from condensation unless you took the mattress out and let the moist air get to the cold surface. Leave the mattress on and the air can't get to the cold surface no matter how cold or moist it gets. Staying dry sleeping on a water resistant (sweat too) foam is the job of sheets and mattress covers.
hope this helps