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Condensation and sweating

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zeil
Master Marine Consultant

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Canada
1314 Posts

Initially Posted - 10/20/2006 : 15:20:56

Docked at Point Roberts, WA, the most North Westerly tip of the US except Alaska, we encountered a severe condensation and sweating problem throughout the boat with water droplets forming on the cockpit ceiling, sides, v berth and walls. Every thing feels damp and wet. Airing stuff takes a good part of the day. The positive side is that we know exactly what is on board but rather not to check it daily...

What to do...

We do have an electrical heater on board, have the hatch and head port slightly open and use moderate heat during the night.

Any suggestions how we can eliminate/reduce the condensation problem?

Thank you in advance

Henk & Johanna
"Floating", a few off your "barnacles".
"Someday Lady" '95 C250WB #151 ('03 - 2016)
"Sea ya" 30ft Bayliner (04-2018 - 09-2018)
"Mariah" '96 C250WB #191 (05-2019 - 15-05-2023)
"Lady J" '00 C250WK #499 (05-2021 - 09-2022)

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 10/20/2006 : 15:47:32

Ever try those water absorbing crystals? Sold at West Marine under the name Watersorb or something like that? Works real good, can collect a tub of water in a couple of days.

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 10/20/2006 : 16:45:23

We spent many weeks and weekends on our C25 in Victoria Harbour last winter. Condensation is part of the deal. Whenever you have a differentiation in temperatures, and a source of water vapour (breathing, cooking, bathing) you are going to have condensation. Its amazing how much condensation results from sleep related breathing in cool temps.
We do as Jim suggested, and have two of the water collectors that use crystals. We also have towels specificly for the purpose of wiping down the ceilings in the morning.

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 10/20/2006 : 17:10:38

The Catalina fiberglass liner is a wonderful attribute of the Catalina line, but it has its disadvantages. Note that boats with carpet on the inside do not have these problems. My first night's sleep on a Catalina the condensation rained on me. Have you tried an oil lamp and a passive vent? Maybe saturated hot air rising out of the boat will deal with the excess.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/20/2006 : 22:36:54

Try a Nicro solar vent, which runs 24-7 using a rechargable battery. As the air cools outside, it deposits excess humidity as dew. The vent expells humid air and draws in the cooled, somewhat drier air. Heating the air inside doesn't reduce its tendency to leave condensation on cold surfaces. Drawing in outside air does, because it's already dropped some of its moisture.

Edited by - Dave Bristle on 10/21/2006 07:11:39

djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 10/21/2006 : 08:38:28

Like Dave said, if you can stand the temp, keeping the inside of your boat the same temp and the outside will eliminate that. Use two of the solar vents. They come with two blades, one to push and one to pull. Set one to push and the other to pull and you should be OK. Cheers.

Edited by - on

Captain Bill
Navigator

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USA
148 Posts

Response Posted - 10/21/2006 : 10:06:39

"Try a Nicro solar vent, which runs 24-7 using a rechargable battery."

I'm with Dave on this one. I installed a Nicro solar 3" vent this past spring and so far it's been great. A perfect replacement for my old Nicor vent. The constant flow of air 24/7 works wonders. Gone is the common "musty smell" I used to experience. So far haven't noticed any condensation. Admittedly, I haven't been at the marina every day or even much this fall season (that's getting ready to change) but so far it's been working great. Highly recommended.

Happy sailing, Bill

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 10/21/2006 : 13:14:00

Zeil and I are North of the 49th parallel, how will a nicro solar vent perform when the cabin is being heated?
I'm staying on my boat tonight, expected temps are -9 celcius.
I'll have my heater on.
Where Henk (Zeil) is, the temp will be about 2 degrees Celcius tonight.
In these northern areas, probably the best idea is a low voltage dehumidifier or the collector tray with the crystals.
Please do not drain the the tray into the ocean or lake, as the crystals are mildly toxic. The collected water should be disposed as you would sewage.

Condensation is a major issue in cool climates with high humidity. Many boats in the Pacific Northwest rig low wattage light bulbs inside perforated tin cans to provide just enough heat to keep a boat warm so things don't freeze up. These low tech heaters however, sometimes create condensation problems, and sometimes they solve condensation problems. They're great for boats that sit unused for days or weeks at a time. If you're cooking and active in the cabin, they will not solve condensation issues in the short term.
Most of the marinas I'm familiar with in the PNW are frugal with their electricity and try to limit consumption. I've found that power interruptions are a weekly occurance during the winter and therefore, my boat has two collector trays with the crystals.
If you use a heater, make sure it will reset itself when the powergoes off. Check it often.

Edited by - on

zeil
Master Marine Consultant

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Canada
1314 Posts

Response Posted - 10/23/2006 : 13:27:17

Thanks for your advise guys...

Our present experiment, to fight the condensation, is with an electrical $59.00 Wall mart heating blanket wrapped around during the evening and lowering temps. (it's time to go South)

Negative of the blanket is movement restriction while on the flip side it provides a wonderful honeymoon kind of setting since we're trying this with only one blanket for now. No... don't get too many ideas, (well perhaps maybe a little bit) after all we're over 60 and friends (married) 40 some odd years.

Here are some specifics: Day mean temp. about 14 degrees... evening/night about 4-10 degrees... During cooking and early evening we point the heater located on the cabin step extension up to heat the air and exhaust it out of the hatch. The heater stays turned off during the latter part of the evening and for the entire night to allow the inside temp. to drop to near outside temps. The blanket seems to generate very little heat to the atmosphere of the cabin. The heat blanket is not used as a bed cover since we have a wonderful warm fleece type cover in the V berth.

Some time ago we installed two crystal trays... they help reduce the condensation but not noticeable.

We'll keep you posted

p.s. Mike when we are in the Calgary, Aberta, area be assured that we'll take you up on your offer for dinner the Dutch way... (we invite... you pay!!)

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/23/2006 : 14:46:16

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by djn
 ...keeping the inside of your boat the same temp and the outside will eliminate that.<hr height="1" noshade id="quote"></blockquote id="quote">
IMHO, temperature isn't the issue--it's humidity. A power vent (solar or otherwise) reduces that by drawing in the cooler outside air during the evening--it's already dropped some of its moisture. If you warm that air, the relative humidity drops substantially, and you won't get so much condensation on the colder surfaces. Your breathing adds a lot of moisture, so the vent continually compensates for that. I wouldn't expect a small container of crystals to help much when you're on the boat--the vent should work much better. It doesn't move so much air that you will lose all of your heat inside. One vent using the exhaust fan does the trick.

Edited by - Dave Bristle on 10/23/2006 14:48:30

PamC
Navigator

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171 Posts

Response Posted - 10/23/2006 : 15:46:23

I have to agree that the fan is probably the best option. If you're living aboard in cooler climates condensation is going to be present in this size of boat at least. However some of the crystal stuff can't hurt. Our friends introduced us to the DampRid bags. They used the crystal stuff in a sealed envelope that absorbes the moisture through a one-way membrane and accumulates it into a sealed bag below. It has a built in hanger and you just throw the whole unit away when it fills. It's great for boats where you don't want that toxic fluid slopping around. I found them in the closet organizer part of our Fred Meyer store, which is part of the Kroger chain. It's there with moth balls & hangers.

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 10/24/2006 : 09:21:15

What I have found works best is a combination of heat and air circulation. The heat reduces the relative humidity in the cabin and the air circulation reduces the formation of a cold boundary layer next to the liner.

Long explanation follows:

Condensation occurs when air cools to the point where it cannot hold it's load of dissolved water vapor. In the boat this usually happens where air contacts the hull liner and is chilled below it's dew point and dew forms on the liner.

There are only a couple ways you can attack this.

1) Keep the hull liner warm (insulation).

2) Reduce the relative humidity of the air in the boat.

You can do this either by
a)heating the air
b)removing water from the air using a chemical or chilling dehumidifier.

3)Circulate the air inside the boat to prevent the colder 'boundary layer' from forming next to the hull liner.

Compounding the problem, the air in an occupied boat is getting an injection of water vapor from our breath, cooking, and sweating. This is where an exhaust fan can be helpful. Unfortunately, in cold weather, this also means drawing colder air into the boat. In the PNW, this cold air will also be carrying a lot of water vapor along with it... which doesn't help matters.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/24/2006 : 22:55:48

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ClamBeach
 ...This is where an exhaust fan can be helpful. Unfortunately, in cold weather, this also means drawing colder air into the boat. In the PNW, this cold air will also be carrying a lot of water vapor along with it... which doesn't help matters.<hr height="1" noshade id="quote"></blockquote id="quote">
When the daytime air cools off at night inside the boat, its relative humidity rises and causes condensation on the cooling surfaces. Meanwhile, as the outside air cools, it condenses on anything it can contact, including the deck and the surface of the water, so its moisture content drops, although it maintains a high relative humidity. But, as the cool, nighttime air is drawn into the boat and heated by the ambient temperature of the air in the boat (and/or by a heater), its relative humidity drops, reducing condensation. Since moisture in air equalizes very rapidly within a space, it doesn't matter much where a vent is placed.

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 10/25/2006 : 09:16:15

"condenses on anything it can contact, including the deck and the surface of the water, so its moisture content drops"

Out here in the PNW there's often so much water load that it condenses as Fog and carries its water load in micro-droplet form. Not what you want to suck into your cabin.

As soon as they get south of Pt. Conception, things will be better.

Like most other 'boat questions' I think the right answer is 'it depends'.

Edited by - ClamBeach on 10/25/2006 09:45:52

Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 10/27/2006 : 00:33:34

If your using shore power use a dehumidifier.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/27/2006 : 07:35:53

(In case anyone's curious, here's the layout and other pics of a Formosa 51...)

http://www.yachtworld.com/core/listing/photoGallery.jsp?slim=quick&currency=USD&units=Feet&seo=0&checked_boats=1199285&boat_id=1199285&back=/core/listing/boatDetails.jsp&boat_id=1199285

Doug and Ruth have moved up a tad...

Edited by - on

zeil
Master Marine Consultant

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Canada
1314 Posts

Response Posted - 11/12/2006 : 22:41:34

Far from perfect but... this seems to work better than most oher experiments!!

With the assistance of two crystal containers placed next to the companion steps and an
electrical heating unit placed on the first or second step of the companion way with the heat
outlet blowing up and out through the cracked open hatch we seem to keep some heat
and the moisture level down.

The heating units intake takes the inside air, heats it and exhausts it up and out while
allowing some fresh air to enter through the hatch as well. Some heated air also circulates
into the cabin keeping it at livable temps. Cracking the bow hatch a tat, depending on
wind direction, will act as air intake but it is rather drafty and colder.

Still... annoying moisture forms wherever cushions/stuff is touching the hull/bottom etc. and...
we learned not to EVER store life vests and/or stuff in the closed aft battery compartment unless
you want millions of mildew spots... Alright... we're slow but learning!!

Edited by - on

existentialsailor
Master Marine Consultant

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USA
1180 Posts

Response Posted - 11/13/2006 : 04:28:04

Put stuff in dry bags, helps a lot.
I got different colored ones and use that as an identification of what's
inside. There are also clear ones.

This place has them.
http://www.sierratradingpost.com/

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 11/13/2006 : 09:58:12

When I put the boat up for the winter, I prop all the cushions up and open all of the access boards in the settees and berths. I also open the small access doors and drawers. This allows maximum air circulation.

Even though we might have a ton of snow on the ground, the humidity can be less than that of a desert so open every thing up and allow the air to circulate.

Edited by - on

kevinmac
Admiral

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USA
732 Posts

Response Posted - 11/13/2006 : 10:36:38

I slept on my boat for nearly 2 months in Portland Henk. I think you might be doing the wrong thing with heat. I cranked my heat up to keep the inside of the boat very comfortable inside, somwhere between 65 and 70 degrees. I did not open anything at night, to keep the heat in. What this did was raise the temperature inside the boat above the dew point, so it would not condense. I did not have any condensation problems. I *do* have condensation issues inside the boat when I am not there and it is not heated.

It uses more power to do this, but it is very comfortable.

Kevin

Edited by - on

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 11/13/2006 : 19:49:24

We spent the weekend on board JD in Cocoa Beach, not exactly artic conditions, but we experienced the same condensation issues.
By morning, the canvas inside of the pop top was literally dripping with condensate. We wiped down the insides of all bulkheads before hitting the sack. But by morning, it was literaly sodden. Another wipe down, and again after cooking breakfast (eggs, ham and great coffee, etc.)
We ran the A/C for 20 mins to dry it all out, but it was way too cool for us (don't laugh!) SOFLA folks.

Paul

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 11/13/2006 : 20:15:10

Just like in tent camping, ventilation is key in reducing condensation. Almost the entire roof of my current tent is open under the rain canopy allowing the warm, moist air to escape.

I remember the old tents that weren't well ventilated. You'd wake up in the morning with droplets everywhere and if you tapped the sides of the tent, you'd get a shower.

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