moisture in our boats
- sailor ja
- Chief Steward
- Posts: 82
- Joined: Sun Dec 14, 2008 11:14 am
- Sailboat: Venture 17
- Location: Richmond VA
- Contact:
moisture in our boats
I get a little bit of moisture in my V21, enough that bugs like to inhabit it when it is sitting in the back yard, the moisture gets trapped under the vinyl cushions and im sure in the V-berth as well. I have since killed all of the ants that took over it with in a months time but I want to keep the boat dry.
any suggestions?
My first thought is to use large silica packets through at the boat velcroed to the side in the v-berth and other areas.
http://www.desiccare.com/unitpaks.html
Second would be to create the slats that the cushions could sit on.
any suggestions?
My first thought is to use large silica packets through at the boat velcroed to the side in the v-berth and other areas.
http://www.desiccare.com/unitpaks.html
Second would be to create the slats that the cushions could sit on.
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johnnyonspot
- First Officer
- Posts: 441
- Joined: Thu Oct 06, 2005 9:19 pm
- Location: Elk River, MN.
Re: moisture in our boats
You might try installing a solar fan on deck to move the air inside the boat. Some people put them in the overhead/deck over the head compartment. Don't know if your boat has a head compartment, though. Some put them in the forehatch. They just need to have sunlight shining on them, obviously. If this is too involved for right now, and the boat is simply sitting in your driveway or next to your house, get one of those small oscillating clip-on fans (or any small fan really) and put it inside the boat to move the air around. It should not take much.
- bubba
- Captain
- Posts: 896
- Joined: Fri Mar 21, 2008 11:04 am
- Sailboat: MacGregor 26M
- Location: Richland,WA Columbia River Lake Wallula "INSPIRATION" w/70 suz. 9' Merc dingy
- Contact:
Re: moisture in our boats
Try a product called Dry Bunk it is about one inch thick mat that allows air to flow under the mattresses. I also use an electric heater with fan in our boat in cool damp weather and open all storage lockers and pile the cushions in a dry location when our boat was on the trailor. Last winter we lived on our M for 3 months on the cold Columbia river with thin ice sometimes forming outside and with the 2 of us our moist breath was enough to cause condesation. We regularly sponged up moisture from under the aft bead and used a product called X14 a bathroom cleaner with some bleach and it kept mold from growing, even with air moving and electric fan heat.
- MD Dunaway
- Chief Steward
- Posts: 88
- Joined: Fri Sep 25, 2009 10:26 am
- Sailboat: MacGregor 26S
Re: moisture in our boats
That seems to be a problem with these boats. I take the cushions and everything out of the boat when I get home and store them in the garage. Like Bubba said open up all the storage lockers. Sometimes I have to scrub off a little mold too. Get the top deck sealed real well so that water doesn't come into the boat. Standing water will evaporate and make the problem 10X worse. If you find another solution please do post it.
Re: moisture in our boats
Moisture is a problem in almost all boats, not just the Mac's. Keep dry z bunk under the cushions and good air flow is a good idea. Here in Seattle we like to keep some heat going in the boat during the "rain event" months. You must keep the temp's low and have a good cord to do this and check on the boat, if you can, weekly. Tracking down any leaks will help, you can also try putting a plastic tarp over the boat during the rainy months. There are other products out there that take the humidity out of the air in the boats, just can't remember the name of the dry bags. They work fine, are easy to use, and can be found at some RV stores.
- sailor ja
- Chief Steward
- Posts: 82
- Joined: Sun Dec 14, 2008 11:14 am
- Sailboat: Venture 17
- Location: Richmond VA
- Contact:
Re: moisture in our boats
bwygirl wrote:Moisture is a problem in almost all boats, not just the Mac's. Keep dry z bunk under the cushions and good air flow is a good idea. Here in Seattle we like to keep some heat going in the boat during the "rain event" months. You must keep the temp's low and have a good cord to do this and check on the boat, if you can, weekly. Tracking down any leaks will help, you can also try putting a plastic tarp over the boat during the rainy months. There are other products out there that take the humidity out of the air in the boats, just can't remember the name of the dry bags. They work fine, are easy to use, and can be found at some RV stores.
I do have a huge tarp over the boat that completely covering the boat from top to bottom and front to back. I guess the boat does stay dry for the most part when it does dry out and after I take out everything in the boat. But if anyone has had to take out the cushions out of a V21 or smaller boat with cabin, it is not exactly a fun chore. So what I was thinking would be to build the slats for the cushions out of bamboo that I have , which will actually raise it up a good inch, and then put the silica packs in between the slats keeping any moisture away that I can, also stuffing the backs in the v-berth as well and other parts of the boat. I do check on the boat about every week. I checked on it tonight after a weekend of hard rain and she seemed good and dry.
where exactly are you placing these fans that are installed? Now for long trips I am definitely going to have to take out every bolt and re-seal them on the boat. from the trim and how the deck is fitted to the hull, the little bolts leak ever so slowly, drop by drop, but these drops collect and cause the moisture to set in, plus steer me away from leaving anything in my boat. I found this out after working on my boat while it was raining and seeing the little drops start to trickle.
I use 3M Marine Adhesive Sealant 5200 and this stuff works great. I had a little trickle leak from my keel lock down bolt and I put this stuff on it as it was leaking and it set in fast and stopped the leak, even looked nice lol.
Does anyone have any paints they would like to recommend for the inside of a boat that will help repel the water and seal? something thick that looks good?
- JoeVacs
- Engineer
- Posts: 125
- Joined: Tue Feb 03, 2009 7:32 pm
- Sailboat: Tattoo 26
- Location: Hickory, NC
Re: moisture in our boats
Part of the moisture problem is condensation. Especially this time of year when it's cool over night and warmer during the day, the difference in air temp, inside the boat verses outside, will cause condensation.
Inside my boat, I just bought some high gloss,exterior, white, oil base paint from Walmart. It has worked well.
Inside my boat, I just bought some high gloss,exterior, white, oil base paint from Walmart. It has worked well.
- kmclemore
- Site Admin
- Posts: 6256
- Joined: Sun Feb 08, 2004 9:24 am
- Sailboat: MacGregor 26X
- Location: Ambler, PA -- MACX2018A898 w/ Suzuki DF60AV -- 78 BW Harpoon 4.6 -- 2018 Tahoe 550TF w/ 150 Merc
Re: moisture in our boats
I keep a milk-house heater in my boat and run it on low all winter long. It just takes the edge off and keeps the inside of the boat warm enough at night to prevent mold and mildew. Not much energy cost, and they are cheap as dirt to buy. Just be sure you have one that has tip-over-shutoff protection.

http://www.northerntool.com/webapp/wcs/ ... 13_1017213

http://www.northerntool.com/webapp/wcs/ ... 13_1017213
- ChockFullOnuts22
- First Officer
- Posts: 215
- Joined: Mon Apr 13, 2009 11:17 am
- Sailboat: Venture 2-22
Re: moisture in our boats
Every single winter and spring, it's the same old drill with my boat: condensation in the fall-winter-spring months, then clean out the mold before it goes in the water every summer. There's always a light film in spots that I have to wipe off every year, whether or not the boat looks and feels dry when I open it up before boating season. I have no deck leaks, and when the boat is stored for the winter, it is covered over with 2 large tarps to keep the snow off of it.
Unless the boat is stored in a temperature-controlled environment (or has a heater running in it), with good air flow in the cabin, I don't see how the condensation and resulting mold issues can possibly be fully avoided--even with a tightly sealed cabin. I personally wish that I had a well-insulated pole barn to store the boat in.
Unless the boat is stored in a temperature-controlled environment (or has a heater running in it), with good air flow in the cabin, I don't see how the condensation and resulting mold issues can possibly be fully avoided--even with a tightly sealed cabin. I personally wish that I had a well-insulated pole barn to store the boat in.
- bubba
- Captain
- Posts: 896
- Joined: Fri Mar 21, 2008 11:04 am
- Sailboat: MacGregor 26M
- Location: Richland,WA Columbia River Lake Wallula "INSPIRATION" w/70 suz. 9' Merc dingy
- Contact:
Re: moisture in our boats
There is another option to move to the desert like where I live with only 8 inches of rain a year but we still get moisture and some mold. The trouble is when I go to Seattle like next week we get condesation quickly and I suggest keeping most everything stored in the boat in dry bags and we put most all food in zip lock bags even cans because they start to rust. I use North Face rubberised dry duffle bags for our persional clothing, our storm suits and cameras. I keep a folding bucket and good sponge by the ballast bucket in the bow to dry up extra moisture when it appears anywhere in the boat. I also use a hydro-stick like you squrt water at each other with to suck up accumilated water in the bildge, especially in the aft under the bead the other lockers are open enough to keep ventilation going.
- Québec 1
- Admiral
- Posts: 1447
- Joined: Thu Dec 27, 2007 1:02 pm
- Sailboat: MacGregor 26M
- Location: Honda BF 50 - MACM0047E303 Lévis, Québec Canada
Re: moisture in our boats
Before re-caulking rub-rail with silicone

After re-caulking:

I initially made as you can see my caulking area between the painting tapes too small thinking the caulking should go on the hull and under the rub-rail. I was wrong and the caulking came off on the tape when I pulled the tape off. I had to re tape with a larger space between the tape with the caulking covering part of the hull and part of the rub rail, and I simply made a bead of silicone between the tape and used my finger to smooth it out. The result was perfectly acceptable.
Q1
p.s. Should rain tomorrow , so we'll see if it worked
After re-caulking:
I initially made as you can see my caulking area between the painting tapes too small thinking the caulking should go on the hull and under the rub-rail. I was wrong and the caulking came off on the tape when I pulled the tape off. I had to re tape with a larger space between the tape with the caulking covering part of the hull and part of the rub rail, and I simply made a bead of silicone between the tape and used my finger to smooth it out. The result was perfectly acceptable.
Q1
p.s. Should rain tomorrow , so we'll see if it worked
- JoeVacs
- Engineer
- Posts: 125
- Joined: Tue Feb 03, 2009 7:32 pm
- Sailboat: Tattoo 26
- Location: Hickory, NC
Re: moisture in our boats
Québec 1 wrote:
I initially made as you can see my caulking area between the painting tapes too small thinking the caulking should go on the hull and under the rub-rail. I was wrong and the caulking came off on the tape when I pulled the tape off. I had to re tape with a larger space between the tape with the caulking covering part of the hull and part of the rub rail, and I simply made a bead of silicone between the tape and used my finger to smooth it out. The result was perfectly acceptable.
Q1
p.s. Should rain tomorrow , so we'll see if it worked
Looks like you did a nice job. However, I wouldn't recomend using silicone caulk (anywhere ) on a boat. You will be pulling off a rubber stringy mess in a year, at best, and have a half stuck mess that you can't clean with anything, that nothing else will bond to, at worst.
Not meaning to offend, but I've read many articles from much more experienced boat fixers than me.
Practical Sailor,April 2005, and August 2006 is one that I could find in my stack. Also Good Old Boat, and Small Craft Advisor have also done stories on this I believe.
- Québec 1
- Admiral
- Posts: 1447
- Joined: Thu Dec 27, 2007 1:02 pm
- Sailboat: MacGregor 26M
- Location: Honda BF 50 - MACM0047E303 Lévis, Québec Canada
Re: moisture in our boats
Hi,
Yeah I read all that stuff too but I live to prove myself wrong most days so...there you go!
I cleaned the existing silicone caulking off with methyl hydrate and a plastic scrapper and found some silicone remover stuff in the hardware store for next time so I figured I'd give it a try and I'll cry if I have to in a years time! I got this silicone cause it said it had a 50% expansion capacity.
Q1
Yeah I read all that stuff too but I live to prove myself wrong most days so...there you go!
I cleaned the existing silicone caulking off with methyl hydrate and a plastic scrapper and found some silicone remover stuff in the hardware store for next time so I figured I'd give it a try and I'll cry if I have to in a years time! I got this silicone cause it said it had a 50% expansion capacity.
Q1
- sailor ja
- Chief Steward
- Posts: 82
- Joined: Sun Dec 14, 2008 11:14 am
- Sailboat: Venture 17
- Location: Richmond VA
- Contact:
Re: moisture in our boats
On the subject of caulking, does anyone see a problem with using this?
http://www.lowes.com/lowes/lkn?action=p ... 00%20White
This stuff is awesome stuff that I have used out of the tube for various parts on the boat. So I am figuring it would work great on the rub rail.
This is what it looks like when it dries.

This was a temporary fix to my keel lock down bolt while I was sailing the boat in the lake this season. Of course I have to take it apart to use it properly after I buy new rubber washers.
http://www.lowes.com/lowes/lkn?action=p ... 00%20White
This stuff is awesome stuff that I have used out of the tube for various parts on the boat. So I am figuring it would work great on the rub rail.
This is what it looks like when it dries.
This was a temporary fix to my keel lock down bolt while I was sailing the boat in the lake this season. Of course I have to take it apart to use it properly after I buy new rubber washers.
- seahouse
- Admiral
- Posts: 2182
- Joined: Sun Dec 07, 2008 9:17 pm
- Sailboat: MacGregor 26M
- Location: Niagara at Lake Erie, Ontario. 2011 MacM, 60 hp E-Tec
- Contact:
Re: moisture in our boats
Hi Sailorja--
Around here condensation during storage periods is reduced by leaving a 40 watt bulb on inside the covered boat. Maybe a boat the size of a Mac would need two bulbs, one at each end. Just enough to raise the temperature slightly above ambient to stop the moisture from condensing on the inside surfaces. Place them low near the floor and convection will keep it dry. (Humidity in an enclosed area will reach equilibrium without a gradient from Brownian motion, so a fan might help, but might be redundant, unless some areas have air that is otherwise trapped).
I like to scatter newspapers around inside surfaces and find it helps with odour control. Just pick up the paper in the spring and everything is clean underneath them. Haven't had any trouble with newsprint staining any surfaces so far.
Maybe lower-wattage bulbs would work. Or a simple timer on the lights can be used to reduce power costs, but that requires some long-term testing on your part to determine the effective settings.
Separating the cushions (and anything else you can) using slats as you suggest sounds like a good idea as well.
- Brian.
Around here condensation during storage periods is reduced by leaving a 40 watt bulb on inside the covered boat. Maybe a boat the size of a Mac would need two bulbs, one at each end. Just enough to raise the temperature slightly above ambient to stop the moisture from condensing on the inside surfaces. Place them low near the floor and convection will keep it dry. (Humidity in an enclosed area will reach equilibrium without a gradient from Brownian motion, so a fan might help, but might be redundant, unless some areas have air that is otherwise trapped).
I like to scatter newspapers around inside surfaces and find it helps with odour control. Just pick up the paper in the spring and everything is clean underneath them. Haven't had any trouble with newsprint staining any surfaces so far.
Maybe lower-wattage bulbs would work. Or a simple timer on the lights can be used to reduce power costs, but that requires some long-term testing on your part to determine the effective settings.
Separating the cushions (and anything else you can) using slats as you suggest sounds like a good idea as well.
- Brian.
