surprising amount of condensate moisture inside cabin

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Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
I have the boat on the trailer and its under a covered area. I pulled the cushions out and brought them in to keep them out of the way and clean during all the winter boat projects, and because of my discovery, Im very glad that I did. my boat has no signs of mildew and dont want to get any started.

during the past few months of windy rainy, stormy weather the boat has remained dry and without issues...
but now that the freezing weather is a steady thing every night, I find that a bit of water will collect in the corners of the liner (in the living area)... as in, I have the bow in the lowered position and the boat leans a bit to the left... so the water collects in the front of the v-berth, and along the wall near the forward part of the port settee.... a couple tablespoons to a half a cup) I have wiped it out several times and it keeps coming back... so it can only be condensate.

as much as I have dealt with repairs due to condensate damage in customers fuel tanks and enclosed equipment cabs, I have never thought about the effects of it in an enclosed boat cabin....
now I can understand why some boats smell as they do and how the mildew starts... when a boat cushion or bedding absorbs a tablespoon of water every week during freezing weather and goes unnoticed, it will surly have a problem before it dries out on its own...
I dont think there would be a problem in areas where it doesnt freeze, or maybe even 1 or 2 nights a year, but when you have a month or more of temps dipping below freezing every night it will become a problem.
and the colder it gets and/or the bigger the temperature swing from daytime to night time, the worse the problem will be, as it will draw more moisture out of the air and deposit it as condensate.
I will ALWAYS pull my cushions every winter now that I have realized how much water is being pumped out of the air and deposited into anything that will absorb it on the boat.
hopefully someone else can realize this before they get a funky smell growing in the cushions:D
 
Feb 6, 1998
11,760
Canadian Sailcraft 36T Casco Bay, ME
I have the boat on the trailer and its under a covered area. I pulled the cushions out and brought them in to keep them out of the way and clean during all the winter boat projects, and because of my discovery, Im very glad that I did. my boat has no signs of mildew and dont want to get any started.

during the past few months of windy rainy, stormy weather the boat has remained dry and without issues...
but now that the freezing weather is a steady thing every night, I find that a bit of water will collect in the corners of the liner (in the living area)... as in, I have the bow in the lowered position and the boat leans a bit to the left... so the water collects in the front of the v-berth, and along the wall near the forward part of the port settee.... a couple tablespoons to a half a cup) I have wiped it out several times and it keeps coming back... so it can only be condensate.

as much as I have dealt with repairs due to condensate damage in customers fuel tanks and enclosed equipment cabs, I have never thought about the effects of it in an enclosed boat cabin....
now I can understand why some boats smell as they do and how the mildew starts... when a boat cushion or bedding absorbs a tablespoon of water every week during freezing weather and goes unnoticed, it will surly have a problem before it dries out on its own...
I dont think there would be a problem in areas where it doesnt freeze, or maybe even 1 or 2 nights a year, but when you have a month or more of temps dipping below freezing every night it will become a problem.
and the colder it gets and/or the bigger the temperature swing from daytime to night time, the worse the problem will be, as it will draw more moisture out of the air and deposit it as condensate.
I will ALWAYS pull my cushions every winter now that I have realized how much water is being pumped out of the air and deposited into anything that will absorb it on the boat.
hopefully someone else can realize this before they get a funky smell growing in the cushions:D
Get the water out... that is what it causing it to condensate. I had a customer about six weeks ago whom I noted had a bilge full of water (actually AF & water) and a sopping wet interior. I suggested he get it dry and not leave AF in it. On a warm day he dried it bone dry with a turkey baster. Was back there on Tuesday and the boat is as dry as a bone with no visible signs of any condensation....
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
the boat seems to be fairly dry... when I put it under cover, i made sure it was dry between the hull and the liner. I tipped it forward, I tipped it backwards and used a floor jack to tip it to either side... and wiped out what little there was with a couple towels to make sure i got it dry. then I rigged a large blower with heater vent hose to blow air in the bilge area to dry up any residual moisture for three weeks... maybe ive missed an area that the water doesnt drain from, but i have put a good effort into it.

Ive noticed this before on other boats ive owned but never paid it much attention... always thought maybe it was leaking a little thru the deck hardware because i never kept them under cover... but this one is kept covered by a carport. its not in a building, so there the heating/cooling/condensate effect will be much greater/faster than if it was inside..
 
May 23, 2004
3,319
I'm in the market as were . Colonial Beach
I have three chemical dehumidifiers inside of my cabin. They work great. I bought them cheaply from Bed, Bath, and Beyond.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
I have three chemical dehumidifiers inside of my cabin. They work great. I bought them cheaply from Bed, Bath, and Beyond.
I use the chem dehumidifiers in the atv trailer all the time.... it helps to keep all the bedding from becoming stale smelling. never thought about placing a couple in the boat....
 
Sep 25, 2008
961
Macgregor & Island Packet VENTURE 25 & IP-38 NORTH EAST, MD
Is the interior vented to the outside? Its good to keep the air circulating somehow (solar vent, fan, open hatch, etc). Maybe your boat is sealed up too good? I leave mine uncovered (yeah, its a pain shoveling the snow off) and my solar vent on. There are plenty of air gaps around the top of the hatch board to help vent also. If your boat is close to your house, you can put a small electric fan inside also, to help move the air around. And, if I go work on the inside when its really cold inside, my breathing will cause condensation inside. Once there is moisture on the inside, its tough to get it to go away in the cold weather.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
Is the interior vented to the outside? Its good to keep the air circulating somehow (solar vent, fan, open hatch, etc). Maybe your boat is sealed up too good? I leave mine uncovered (yeah, its a pain shoveling the snow off) and my solar vent on. There are plenty of air gaps around the top of the hatch board to help vent also. If your boat is close to your house, you can put a small electric fan inside also, to help move the air around. And, if I go work on the inside when its really cold inside, my breathing will cause condensation inside. Once there is moisture on the inside, its tough to get it to go away in the cold weather.
its sealed except for the ventilation around the sliding hatch and companionway board.... so there is enough ventilation for new moist air to come in when the temps warm in the daytime, but not enough to keep the condensate in suspension with the air when the temps drop... a fan should help with that.

mostly, I was surprised at the amount of water that would be wrung out of the air every few days inside the boat...
 
Aug 16, 2006
281
Ericson 32 Oregon coast
Center, a small oil filled electric heater will stop it.

maintaining a temperature of 50 degrees would do the trick. The chemical water collectors will also help.
 
Oct 11, 2012
56
Clark-San Juan 23 Kings Mountain N.C.
Re: Center, a small oil filled electric heater will stop it.

I run a small ac heater in the winter to keep the inside dry. I have a lot of marine carpet and have no problems with mold and mildew. I use a small wet and dry vac for times when I have left a hatch cracked or open.
 
Nov 23, 2011
2,023
MacGregor 26D London Ontario Canada
In the summer I run a small low amp muffin fan in my bilge. It just blows down the starboard side. Makes a big difference.
I was going to have it run all winter too but decided against putting a charger in for the winter.
There is 2" of ice in my bilge areas. (Thanks leaky windows and chain plates.) That's 2" less than when I got it last winter! I am not concerned with 2" of ice. 6" maybe.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
For 13 years I have run 3 inch computer fans in cowl vents and powered them with a 5 watt solar panel. The boat stays dry all of the time.
 
Nov 23, 2011
2,023
MacGregor 26D London Ontario Canada
For 13 years I have run 3 inch computer fans in cowl vents and powered them with a 5 watt solar panel. The boat stays dry all of the time.
Do you just have one battery or two? I've been thinking of running 2 more muffin/computer fans but was a bit concerned with draw. I do have a 18 watt solar charger so I'm probably ok.
So now it looks like I will cut a hole in my aft locker and get that vented.
Next I have to get a battery meter installed so I know what I'm working with.
 
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