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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

V-Berth moisture

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johnnyd
Deckhand

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USA
23 Posts

Initially Posted - 10/30/2021 : 12:25:24

Anybody have tips on controlling the moisture in the V-Berth? It seems to get quite a bit of moisture on the roof and sides. Also below the cowl is usually wet. I don't understand because I installed a new one and caulked all around it. Seems to be coming from the inside of the cutout. I live in Seattle so It gets plenty of moisture. Non-power solutions would be ideal. Any tips would be appreciated. Thanks!

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 10/30/2021 : 12:36:09

NICRO solar powered vent should help.

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 10/30/2021 : 12:57:02

I can't think of anything resembling a cowl near the v berth, and think it must have been owner-installed.

The v berth is a confined space with little or no ventilation. When you sleep in it, you perspire and breathe out warm, moist air that, in cool weather, condenses on the v berth's overhead and runs down the walls and soaks into the cushions and bedding. If it isn't well ventilated during the day, it will still be there when you climb in at night, and you'll add to it each successive night. You can add a solar powered fan to keep air moving through it, but the bottom line is that C25s weren't designed to be lived in year round. They aren't insulated, and they have no HVAC facilities. Depending on your venue, most people store their boats during cold weather.

Leaks can come from anyplace where there's a seam or fitting, but the second most likely source of a leak is in the anchor locker.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Lee Panza
Captain

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USA
465 Posts

Response Posted - 10/30/2021 : 23:03:40

Johnny:

It sounds like you can rule out rainwater leaks, so your problem is most likely condensation - especially in that part of the world; condensation produces moisture on the interior surfaces of the hull and on the overhead at night.

You're probably aware that relatively warm air can hold more moisture vapor than relatively cool air, and that moisture-laden air tends to give up its moisture when it is cooled. This results in condensation - the formation of liquid water - where the humid air contacts a cooler surface, and every night the surfaces exposed to the exterior cool as the ambient temperature drops. You mentioned a "cowl", which I'm taking to mean a passive ventilation opening between the interior and the exterior of your boat.

Every day, the air in the V-berth area warms and expands, exhausting through that cowl. Then, every night as the ambient temperature drops, the air in the V-berth area cools and contracts - and it draws humid air in from the outside as it does.

The overhead and the sides of the hull cool as the outside temperature drops. As they do, they cool the air inside; but they cool it largely through contact, and that's where the condensation takes place.

The classic relief for condensation is to keep the air warm, like leaving an incandescent light bulb burning all night (it doesn't take much heat to do the job).

Moisture absorbers (like DampRid) can help, but they're fighting a losing battle if your cowl allows fresh, moist air in every night (that's definitely not a factory feature, and the previous owner who installed it didn't realize what they were doing).

I'd recommend closing-off that cowl, and then begin using a passive dehumidifier (I mentioned DampRid because it's what I've found works in our slightly less damp San Francisco Bay area). If the air in the V-berth space is not being recharged with moisture every night, and if you can remove whatever moisture is in the relatively stagnant air in that space, you'll stop getting condensation on the walls and overhead.

The trouble with a destination - any destination, really - is that it interrupts The Journey.

Lee Panza
SR/SK #2134
San Francisco Bay
(Brisbane, CA)

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 10/31/2021 : 13:58:46

I'll second (or third) the solar vent. No electrical work needed--it's self-contained. But it takes cutting a hole in the boat unless you can use or modify the one for your "cowl".

In my experience (not in the Pacific NW), and from what's written, the solar vent, running all night on juice generated during the day, directly expels the warm, moist daytime air from the cabin, which draws in cooler night air that has already dropped much of its moisture. If you need to add a 4" hole somewhere, a common place is the forward hatch, for a few reasons:
1. It exhausts the air relatively far from where the cooler air will be drawn in (the companionway) so it's an efficient exchange.
2. The sloping hatch isn't a place you're likely to step on, as the cabintop would be, especially near the mast.
3. If you decide you don't like it, you can probably replace or repair a hatch more easily than you can fill in a 4" hole in a cored deck.

My solar vent runs 24x365, even under the winter shrink-wrap. My 14-year-old fabric v-berth cushions are like new--no odors, and the main location of mildew is a small circle on the deck around the outside of the solar vent where that warm air condenses as it's exhausted.

Just be aware that Nicro solar vents are notorious for lasting only a few years. They sent me a new motor kit for my first one (no questions asked about the warranty), and I bought a second vent--all in the space of 14 years. (I caught it on sale for about 40% off at Defender.)

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 10/31/2021 : 15:54:09

I think Catalina may have offered cowls as an option. I'm pretty sure a PO (Prior Owner, johnnyd) replaced one on my boat with a solar vent. The original interior trim rind didn't match up. Mine had a 3" hole and the documentation from Nicro said that size would change the air is a boat the size of a C25 every 30 minutes or something like that (10+ year old memory!). with vents in the companionway boards, air wouls flow from there through the boat and out the vent in the v-berth.

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN

Edited by - dmpilc on 10/31/2021 15:58:09

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 10/31/2021 : 20:00:06

While you don't want to pump out the air that was just drawn in (a reason for putting a vent well forward of the companionway), in general, humidity equalizes itself very rapidly in an air-space. The V-berth won't stay humid for long if the salon is substantially less so.