Cold Weather Hull Condensation

[redsky49]

We are currently parked in northern Florida and have been dealing with considerable hull condensation while running the interior heaters at night (28 degrees forecast tonight - brr...). While that may not sound terribly burdensome to my DC and Annapolis live-aboard friends, I am starting to encounter some (lots?) of mildew where items are stored against the hull.

I have taken the usual steps of leaving solid locker doors open, moving fabrics and paper items away from the hull surface, trying to maintain an air space at the inner hull surface,etc. but I seem to be losing the battle.

Are there any solutions out there - other than not heating the boat interior to the dew point? In the meantime I have discovered that the vinegar version of Windex (as opposed to the ammonia version) is useful on hard surfaces to remove mildew and somewhat retard its reappearance.

I am not keen on fabric attached to hull surfaces for several reasons so I am ruling that out for now.

Suggestions?

[RTB]

You are not alone. Same here in Texas (about the same latitude as you probably. We have taken the cushions out to air dry on nice days. My wife woke up this morning because a drip of condensation hit her in the face.

Other than going south where it stays warmer, probably the best bet is to buy a good de-humidifier.

Yeah, vinegar works to clean and kill the mold. My wife just mixes it with water and uses a spray bottle.

Good luck, buddy.

Ralph

[Hudson Force]

I might be your neighbor as we are her in Northeast Florida. Neighbor or not we live with the same condensation. I choose not to make much of a battle with it. Most of my efforts are simply to direct the condensation drips to run eventually to the bilge. Sure, I have some mold and mildew issues; I have some edges of bedding at the sides of my mattress damp; sometimes I get a drip from my overhead hatches....

'seems to come with the territory!

[DeepFrz]

Insulation, ventilation, circulation, dry heat...

Are your cabin heaters vented to the exterior? If not then they will just be adding to your problem.

[redsky49]

Originally Posted by DeepFrz

Insulation, ventilation, circulation, dry heat...

Are your cabin heaters vented to the exterior? If not then they will just be adding to your problem.

Non-combustion type - heat pump and small electric space heater.

A de-humidifier is possible, though lowering the interior humidity sufficient to reduce condensation will probably result in Sahara Desert-like dry air.

I am going to use the small local Hellla fans to move some air to stagnant corners of the boat.

[Jeraden]

After having battled so much condensation, we decided to try installing ThermoGuard insulation in all lockers and cabints. So far, we are very happy with the results. ThermoGuard is availability at Home Depot online only. We cut to size and it seemed to stay in place without using glue or tape. Temp is 4° tonight and no condensation. Before we insulated, we used small fans. This seemed to help also.

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[Lepke]

Moist air condenses on any cold surface. Human breathing produces moist air. Cooking a lot more. Also, moisture is a by product of propane. If you want to live as old as me, you shouldn't be using propane inside a hull.
The best solution I have found is heating with a diesel, pellet or wood stove. With combustion you're drawing in fresh air that probably has a lower moisture content than the air inside that the stove is using for combustion. An electric heater is just heating wet air. If you're away use a dehumidifier. I live aboard a wood boat and can keep my boat dry. What helps the most is venting cooking vapor outside.
Insulation on the all the cold surfaces help the mold problem. In WWII submarines had cork on the inside hull. There are products that can be added to any paint or varnish that kill mold trying to get a foot hold. I put it in all my paint.

[Jeraden]

Yes, additives to paint is a great idea! Glad I used it, it works well.

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[dbostrom]

We have an EvaDry 2200 solid-state dehumidifier, as mentioned in and approved by Practical Sailor. Works a treat. The unit's only disadvantage is that it does not come with a deicing function-- just add a thermal snap switch to the cold side of the exchange fins to provide that. (Practical Sailor sez put it on a timer but that's not really optimal).

Previously had moisture accumulation above headliner despite the boat generally being dry and on maintenance heat. No more.

[This gizmo works well enough that I'm going to husk the guts out of the original housing and make it a permanent part of the boat. I could easily see this working for a boat w/solar on a mooring, too; excess production shunted to dehumidification, to the tune of about 5 amps...]

[Hudson Force]

There's a huge "latitude / attitude" factor at play with all this. I spoke with little concern for this problem earlier simply because I am in Florida. Admittedly, North Florida like the OP, but winter only comes here three days at a time and the lowest rare daytime highs are usually in the fifties.

Almost all of our cold days in the Florida are clear days without clouds to hold in the surface heat from the previous day. Our cold days ar almost always bright sunny and drying.

Posts here from people in Seattle, Alaska or the Great Lakes are not likely opening their hatches for dry air on their coldest days. 'seems like there can be some different strategies by latitude.

[atoll]

ventilation will stop the condensation,leave some hatches open a crack to get air through the boat

[redsky49]

Agreed that the problem is different for Alaska than Florida. I suspect that the higher relative humidity here is also a factor.

Today's solution - cleaning out the hull side lockers and wiping all the surfaces with the vinegar version of Windex. Also forces us to toss some of the crap we have accumulated and rearrange the remaining stuff.

Fortunately, the cold spell we, and the entire east coast, are experiencing will be short lived and we can get back to the more moderate conditions we expect here at 29.3 degrees North.

[VOYAGER II]

We are in Jax and have a $150. dehumidifier on our 42' ketch, we run it about 4-5 hours per day. We seem to have beat the problem. Last year we experienced the same problem that you're having.

[PatC47]

Originally Posted by Hudson Force

I might be your neighbor as we are her in Northeast Florida. Neighbor or not we live with the same condensation. I choose not to make much of a battle with it. Most of my efforts are simply to direct the condensation drips to run eventually to the bilge. Sure, I have some mold and mildew issues; I have some edges of bedding at the sides of my mattress damp; sometimes I get a drip from my overhead hatches....

'seems to come with the territory!

try using old panty hose filled with kitty litter. it greatly decreases ther humidity in the air hense less condensation - pat

[wiekeith]

I had the same problem last winter, this winter I bought a dehumidifier, which has reduced condensation dramatically. It's a desiccant type, as opposed to a compressor type, so it's quite quiet and doesn't suffer from freezing.

It cost about £100 here in the UK, and uses 300 watts when operating, which is only for about ten mins every couple of hours on average. I've got it set for about 50% humidity and it seems to extract about a liter of water per day.