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Solar Vent Placement

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JimV
Deckhand

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USA
20 Posts

Initially Posted - 10/19/2016 : 08:51:55

I'm in the PNW and I need some advice on solar vent placement and quantity of vents for condensation control. We will be sleeping on board every other weekend or so and sailing her as often through the winter.

First off, do I need more than one solar vent? I was thinking two would be better than one but I might be missing something?

Also, what is the best place to locate the solar vent(s)?

Thanks in advance!

Jim
Eugene, OR
"Caerulea" - 1980 C25 SR/SK #1720

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 10/19/2016 : 09:16:45

Some considerations:

1. They're not totally silent, and night is when they're most important--to exhaust the moist daytime air, which draws in night air that's given up moisture as dew. So where do you want to sleep?

2. Humidity in an air space equalizes very rapidly, so placement isn't as critical to its function as some might think.

3. What happens if you decide you don't like that kind of vent, and now have a big hole in the boat? If you mount the vent in the forward hatch, you have the option of replacing the hatch--although you might have to find somebody who is parting out a C-25 of similar vintage. (Later years had different hatches.)

4. You don't want to be stepping on the vent--a location such as on the coach-roof over the head may seem good, except that puts it near the mast where you might be scrambling to drop the jib. The forward hatch is probably not a place where you'll be walking or crawling.

So, you probably see where I'd be leaning...

Others can give opinions on how many vents--I'd mostly listen to FL and PNW owners on that issue.

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

Edited by - Stinkpotter on 10/19/2016 09:18:14

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 10/19/2016 : 09:18:29

I'm not sure this is the best forum to be asking that question, because few of our members live aboard in the winter. There's a good discussion of the subject on the Cruisers Forum at this link. http://www.cruisersforum.com/forums/f74/prospective-boston-liveaboard-heating-and-condensation-168315.html

Within that link there are several other links that might be helpful.

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

Edited by - Steve Milby on 10/19/2016 09:23:26

JimV
Deckhand

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USA
20 Posts

Response Posted - 10/19/2016 : 09:48:40

Stinkplotter - We sleep in the V berth, there is a ton of condensation above us when we wake up, like large drops all along the ceiling. I assumed it was from the moisture in our breath as we slept. We both don't mind the white noise of a fan. My thought was that if you have vented slots in the cribboads towards the back of the boat for air to enter, the further the solar vent was forward on the boat the more complete airflow you would get from stern to bow on the boat. Sounds like you are saying something a bit different that I haven't quite rapped my head around. I would love to learn more about "Humidity in an air space equalizes very rapidly" If you have a minute to explain that in detail that would be great, I am always willing to learn :)

Steve Milby - Thanks for the link, I haven't read this one yet. Before posting this I read a few lengthy links and was hoping to get some exact advice on placement and quantity for the C25 in specific.

Jim
Eugene, OR
"Caerulea" - 1980 C25 SR/SK #1720

OLarryR
Master Marine Consultant

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USA
3367 Posts

Response Posted - 10/19/2016 : 10:26:27

Generally, one vent is all that you need - It displaces the warm moist cabin air, periodically (ie. once an hour), with cooler outside air. Without a vent, the moisture in the warm cabin air may condense inside the cabin as evening/night time temps cool the cabin. As the cabin air is displaced by cooler moist air, that moisture would also eventually condense if it was not for the vent continually displacing warmer cabin air with outside air.

For the vent to work moist efficiently, it is best to locate the vent away from where cooler air would either be drawn in or pushed out of the cabin. The companionway boards have slots/vents and so that is the most obvious place that air is drawn in or pushed out. So, a solar vent would be best placed as far forward in the main cabin or even further forward, in the VBerth area such as in the Plexiglas hatch to assist in moving all the warm air in the cabin, eventually out of the cabin. My solar vent is located on the port side inside the main cabin adjacent to the bulkhead. The downside is that perhaps the VBerth area air would not be removed as efficiently as the air in the main cabin since there are no passive vents in the VBerth area. I also have a dessicant type moisture remover hanging from the hanger rod above the porta potti to sort of address the lack of air movement in the forward compartment. I know that the use of the dessicant canister will not really be that effective as the solar vent is continually circulating and bringing new air...but this is my setup even if it makes no sense. The dessicant canister I have is not sold by West Marine or Defender but if you search the web for "Eva DrY" this is a canister with a display window to view the color of the dessicant. When the dessicant changes color, then you bring the unit home and plug it into the AC overnight. That heats the unit up and the moisture collected by the dessicant is dispersed. Then you can re-use the dessicant canister. The above two stores only sell one time use dessicant canisters or units that must be plugged into the AC onboard the boat. During the summer months, the Eva Dry will change color in about 2 weeks or so. The unit can be re-used hundreds of times and Eva Dry sells various sizes/capacities for removing moisture. (I think they mainly are used on RVs.)

Probably best to just go with the solar vent as the solar vent probably negates the benefit of the Eva Dry.Or...if you want to have one work against the other, then go for both.
i
My boat s in the water year-round and I have used both units for over 10 years now and my cabin has never had a musty or moisture issue.

One thing to be aware of regarding the Solar vent. While the Nicro vent is the most popular unit, these units running 24/7 eventually break down from both motor carbon brush wear and shaft/bushing wear. they generally will fail after about 1-2 years if continually used. You canc atch the Nicro vents on sale occasionally at West Marine. West Marine does sell extended warranties on a lot of their products and it is a std price depending on years extended and not on failure rate of a specific product. In the case of the Nicro vents, consider a 3 year extended warranty. The cost of the warranty is peanuts and so if you never use it...after 3 years then be satisfied you got three years out of the vent. But if it fails within 3 years, West Marine will just give you a new Nicro Vent. (I think the warranty for 3 years is between $12 -$20.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

Akenumber
Navigator

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USA
247 Posts

Response Posted - 10/19/2016 : 17:35:38

Mine is above the head. I usually only leave it on when onboard. We sleep on the boat in the v berth every few weekends or so. After replacing it with a non functioning unit I noticed a lot less condensation in the v berth. So, I would say it's a good out of the way location and it also acts as a far fan. Also in that location it doesn't seem to see a lot of water if it is opened up.

Ken
San Diego
84 C25 SR/FK 4116
The KRAKEN

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 10/19/2016 : 19:32:41

Our boat had 2 passive vents when we bought her, over the v-berth and over the head. We replaced the one over the v-berth with a day/night solar vent and it worked very well. A solar vent installed in a 3" hole will replace the air in a C-25 completely in a very short amount of time, something on the order of every 20-40 minutes. air intake can be from the vents in the companionway hatch boards.

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

Bladeswell
Captain

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USA
490 Posts

Response Posted - 10/19/2016 : 19:47:16

Hi Again,

Though not presently working, mine is located in the center port and starboard wise in the v berth. Probably mid way between the forward hatch and the anchor locker. I believe it was installed where there would normally be a small sky light. I do plan on replacing mine with a new one. Thankfully, being on the west coast I haven't had any problems with condensation yet but it is getting colder by the day now.

Bladeswell

C25 TR FK Hull #973 1979 L-Dinette. So.Cal.

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 10/19/2016 : 21:26:25

quote:
Originally posted by JimV

...I would love to learn more about "Humidity in an air space equalizes very rapidly" If you have a minute to explain that in detail that would be great, I am always willing to learn :)

I did a quick search for a source I could quote... Could only find a statement by a building company that humidity equalizes in a closed air space faster than temperature does. My only point was that the concept of putting the vent as far as possible from the companionway (with slots in the crib-boards) is not as critical as you might think. But putting it adjacent to the companionway might not be optimal, especially with two people sleeping in the V-berth. The key is removing interior air and replacing it with outside air as temperature drops. An active vent (such as a solar vent) does that at a surprisingly rapid rate.

We also experienced major condensation overhead when sleeping aboard--probably mostly from our breath. But some condensation happens overnight when you're not aboard, as the daytime air cools. Over time that supports mildew growth throughout. I bought a solar vent for Passage, but sold her before I installed it. So it went into Sarge.

If you don't mind the small hum, I'd suggest mounting the vent in the forward hatch--it won't be under foot on deck, and you won't be cutting a large hole in the deck. I think that would have been my choice.

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

Edited by - Stinkpotter on 10/19/2016 21:28:01

sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 10/19/2016 : 22:23:38

Jim, are you sleeping on the hook or at a dock with shore power?

My experience may be somewhat different than what my fellows on this forum have already posted. We have one Nicro 3" MiniVent 1000 Solar mounted in the head. This has not been sufficient to prevent condensation in the boat in cool temperatures without heat. I now run a small electric space heater inside the boat continuously in cooler months, regardless of whether or not we're on the boat, which prevents condensation inside the boat.

Before I continue, the MiniVent 1000 Solar has no battery and only operates during the day. Also before I continue, I second Dave's recommendation to install any new vent in the hatch cover.

If you have shore power, an electric heater can raise the temperature or the air inside the boat enough so that you will not have condensation problems. If you do not have shore power, I suggest not going with the low end vent I have on my boat, and instead installing one with a battery that will operate after dark.

One last thing, my PO installed our vent in lateral line with the forward bulkhead that separates the head form the v-berth. This is now causing a little extra difficulty as I make a door to separate the head from the forward v-berth. So once again I'll second installing a vent in the hatch like Dave suggests.

Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2 (sold - yay!)
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
https://whichsailboat.com/2014/07/27/catalina-25-review/

JimV
Deckhand

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USA
20 Posts

Response Posted - 10/20/2016 : 10:36:03

Thanks guys for the input, we have shore power most of the time but we do wander off and stay on the hook occasionally. I was planning to use a low wattage electric heater continuous as well as a day/night solar vent. It sounds like I only need one solar vent placed on the hatch.

I'll report back when and let you guys know how well it works.

Jim
Eugene, OR
"Caerulea" - 1980 C25 SR/SK #1720

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 10/21/2016 : 06:48:59

quote:
Originally posted by JimV

...I was planning to use a low wattage electric heater continuous as well as a day/night solar vent...

From BoatUS:

quote:
Electric heaters, another hazard Seaworthy has addressed
before (see The Boater�s Guide to Winterizing at
www.BoatUS/Seaworthy/winter), continue to be a major
source of AC electrical fires aboard. While safer heaters
have been developed that are less prone to being tipped
over or to igniting anything combustible that falls on them,
they still draw a great deal of power, and any corrosion in
the shorepower system (or worse, household extension
cords powering heaters) will tend to build up heat somewhere
that can result in a fire. BoatU.S. continues to recommend
not using heaters in lieu of winterizing, and never to
leave a heater running if there is no one aboard.

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 - 10/21/2016 : 11:11:15

The other advantage to the solar day/night vent is that is runs constantly. I noticed that it smelled much nicer in our boat after I installed it. I think they cost around $100-$150, depending on if you can catch one on sale. Mine mounted just in front of the factory skylight, if I remember correctly. Since a vent was already there, to be replaced, I had to make sure I bought one to match the existing hole. I was not able to match screw holes all the way around or reuse the wood trim ring inside, but it still worked.
Since I used a cover over the cabin house, I did not replace the vent over the head, left it passive since it would have little to no chance to pull in solar energy without cutting a hole in the cover.

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 10/21/2016 11:14:02

dmpilc
Master Marine Consultant

Members Avatar

USA
4593 Posts

Response Posted - 10/21/2016 : 11:20:13

If you are going to run a heater in your boat over the winter, I suggest this one:
http://www.westmarine.com/buy/west-marine--portable-cabin-heater--7867500
They can sometimes be found for less $ on Ebay. I've got 2, one for the boat and one for the basement of our family vacation home. It has a setting for just above freezing that I like.

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

JimV
Deckhand

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USA
20 Posts

Response Posted - 10/21/2016 : 15:42:58

dmpilc...I just ordered that same heater from Amazon but in black.

Stinkpotter...thanks for the BoatUS link. Safety is not lost on me, I am in the middle of rewiring and replacing 95% of the shore power on board, new Type 3 10/3 AWG Triplex Tinned Marine Wiring, new main breaker, new GFCI outlets and new 12v charger. The only component I'm not replacing is the shore power inlet plug, upon inspection it has virtually no corrosion and looks like it was never used. I wonder what their take on these "Dehumidifiers"

http://www.westmarine.com/buy/west-marine--air-dryer-with-fan-dehumidifier-120v-ac--7867518?recordNum=3

are. They seem like they are just a 100w heater and they recommend that they are left on 24/7.

Jim
Eugene, OR
"Caerulea" - 1980 C25 SR/SK #1720

pearson39b
1st Mate

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93 Posts

Response Posted - 10/22/2016 : 08:25:33

Not sure how effective it was, but a sailing club I belonged to the the San Francisco Bay area used to leave an incandescant bulb on in their boats at the dock. Had the added advantage of letting you know the AC was hooked up and on so the batteries were recharging.

Sailor Jerry
C-25 "Sea Song"
1978, SK, Std.
Pepin, WI

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