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Old 05-11-2018, 17:44   #1
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Condensation

Ok so something I've notice over and over again on Harbinger. I get some condensation on the overhead in the vberth when it's not cold enough to warrant firing up the diesel heater and I'm using an electric utility heater to warm the boat, it is not present at colder temps when I'm using the diesel heater (Dickerson Newport) Its not much and it doesn't drip down that I've ever seen just enough to be slightly damp. I wonder why it would be there at comparability warm temperatures but not when it gets really cold seems to only happen at around 45-55F but not when the temperature is below freezing. Strange. I wonder if someone here could shine some light for me?
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Old 05-11-2018, 18:09   #2
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Re: Condensation

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Originally Posted by SV_Harbinger View Post
Ok so something I've notice over and over again on Harbinger. I get some condensation on the overhead in the vberth when it's not cold enough to warrant firing up the diesel heater and I'm using an electric utility heater to warm the boat, it is not present at colder temps when I'm using the diesel heater (Dickerson Newport) Its not much and it doesn't drip down that I've ever seen just enough to be slightly damp. I wonder why it would be there at comparability warm temperatures but not when it gets really cold seems to only happen at around 45-55F but not when the temperature is below freezing. Strange. I wonder if someone here could shine some light for me?

For one thing, the diesel heater is pulling fresh (dry) air into the boat (combustion air).
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Old 05-11-2018, 18:25   #3
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Re: Condensation

I also have the Newport stove. It dries the boat nicely because it pulls the humid cabin air in for combustion which will draw fresh dry air into the boat through whatever vents to outside you have. Great heater I've had one on two boats.
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Old 05-11-2018, 18:57   #4
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Re: Condensation

Oh I love that heater, looks nice and really warms the boat quite well, just didn't think it would draw in enough air to make a big difference as far as condensation went especially since Harbinger is marginally insulated at best and I don't take it easy as far as humidity producing activities go; shower every other day (pierside only) and cooking involves lots of boiling water be it for pasta, potatoes, clam boil or soup (soup has to be one of my favorite things to make/eat) but I could go on about food for forever and a day so I'll stop now, and get back to where I was originally going... I think.. that with all the water I put into the air on board I'm actually more suprised there isn't more condensation, and that the heater is drawing that much air during combustion.
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Old 05-11-2018, 19:42   #5
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Re: Condensation

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Old 05-11-2018, 20:07   #6
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Re: Condensation

With winter coming fast, it's tempting, but the tiny water droplets don't make me itch for days and in a week or two or so the diesel heater should come into it's own and everything down below should be as dry as a mummy's rear end besides I like winter sailing the air is denser so you get more out of a given breeze and ice on deck around here usually* isn't an issue although a few times a year the harbor freezes....
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Old 05-11-2018, 20:59   #7
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Re: Condensation

Active ventilation is the key, even when temps don't require it
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Old 05-11-2018, 21:08   #8
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Re: Condensation

Active ventilation is the key, even when temps don't require it
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Old 05-11-2018, 21:18   #9
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Re: Condensation

Sooo...it seems Active ventilation is the key, even when temps don't require it. LMAO

It's one day cold(50-60) two days hot(80+) here lately.

My boat doesn't produce condensation which has always amazed me but I've never had it any where truly cold either.
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Old 05-11-2018, 22:19   #10
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Condensation

Condensation is present when the surface temperature hits the dewpoint. In the summer, hot air carries a lot more moisture. In the winter the cold air carries much less. If warm moist air hits a cold surface, you have condensation. You can get rid of it on a surface by blowing warm dry air over the surface. The dry air will pick up the moisture. The warmer and dryer the air, the faster you rid yourself of the condensation. Its just simple physics.

In the sky, the clouds occur at the dewpoint.
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Old 05-11-2018, 23:14   #11
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Re: Condensation

I find little air movement in our V and can trap moisture from breathing overnight. Could crack the hatch but that gets too cold. A fan helps
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Old 13-11-2018, 12:48   #12
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Re: Condensation

I still have some tweaking to do to get it right, but I pointed a fan on my v-berth hatch and the condensation is notably reduced overnight now.

It's like your car's windshield, when you want to defog it, blow air on it.
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Old 13-11-2018, 14:08   #13
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Re: Condensation

Wintered over aboard in Norfolk with electric heaters. Had so many 'leaks' the boat was always wet inside. Wasn't till things warmed up and the electric heaters were no longer needed that I discovered that all those leaks were just condensation. Some kind of vented heater is really necessary if you are going to be spending time aboard in cool weather. Even though it's not vented, didn't have any issues with condensation with a propane catalytic heater in temps down to the high 40's low 50's.
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Old 17-11-2018, 13:08   #14
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Re: Condensation

In a slip, a fan is pretty much a necessity, on a mooring or at anchor, there really is no reason why a venturi system cannot adequately ventilate a boat. Obviously a catalytic heater adds moisture to the air, while a stove with a chimney removes it.... at least obviously to me. I've run catalytic heaters for just that reason in extremely dry climates. The abrupt temp change by a cold surface results in a lowering of the dewpoint of the air at the contact point which causes condensation... the reason windows frost or steam up. A foam sandwich or wooden boat is going to be far less of a problem than a solid GRP or metal boat...... Aluminum is by far the worst choice. (for other reasons also)



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Old 17-11-2018, 13:16   #15
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Re: Condensation

I get that condensation all the time. I suspect that the very moist air inside the boat, being warmer than the external air at night (given that the water you are sitting in is warmer than the ambient air) causes the condensation on the large cool plate of the the underside of the foredeck. And mine is even sort of insulated in that is has a 1/4" sheet of plywood sandwiched in the deck there. I use tubs of DampRid (Calcium chloride powder) and they soak up the moisture pretty well while I am away.

editops, I see I didn't answer what you asked. I suspect that air that is below freezing has already lost a lot of its moisture and doesn't have much to condense on the inside of the boat.
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