Increasing air flow in the v-berth

Nov 15, 2015
268
J J/30 Seward, AK
After installing solar power, the last thing I use shore power for is a 120VAC convecton baseboard at night which does a really good job of keeping the whole cabin (and v-berth) dry year round. I'd like to be free of needing shore power at all, and of course the baseboard doesn't work when I'm anchoring away from the slip. When it gets colder in the winter I'll run my Dickinson Newport more often but in the summer it's probably not cold enough to run it at night (I haven't installed in the chimney on the Newport yet so I don't have experience with it). I'm a liveaboard so I'm generating moisture every night of the year.

My thought to combat moisture in the v-berth was to come up with some clever way to increase air flow. I have a 3" Marinco solar fan in the center hatch just behind the mast in the cabin, but I want to avoid putting a 3" Marinco vent in the middle of my foredeck if possible. What other ways have others worked around this problem?

Some options I have considered:

1) Try to increase airflow through the top-rear of the anchor locker, but I'm concerned about water leaking into the v-berth when the bow goes under in rough seas.

2) Add Ducting and a low-RPM (silent?) 12VDC fan from the closet locker to the starboard cabinet just fast of the bulkhead to push air into the v-berth, and a complimentary one to the port side bulkhead cabinet to take the air out.

3) Just install a 12VDC fan on the top of the starboard closet bulkhead to push air in, without a way for it to come out.

4) Try to figure out some way to generate convection heat from some kind of 12V heat strip or something, one each laid on either side of the v-berth railing. No idea what device or contraption would do this but the aesthetics make sense.

Options #2 and #3 would have the advantage of moving warm air from the Dickinson Newport diesel heater when it is running.

Anyone have any thoughts on this? Is the theory involved even correct?
 

BillyK

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Jan 24, 2010
502
Catalina 310 Ocean City, NJ
I installed a solar vent in the middle of the hatch over the v-birth..
 
Dec 2, 1997
8,709
- - LIttle Rock
To to the most good you need to pull air through the cabin and out an open hatch over the v-berth. I found that two 12v oscillating fans--one in the main cabin near an open companionway hatch and one on the v-berth bulkhead--do a great job of keeping the whole boat comfortable on a hot still night.
 
Nov 15, 2015
268
J J/30 Seward, AK
To to the most good you need to pull air through the cabin and out an open hatch over the v-berth. I found that two 12v oscillating fans--one in the main cabin near an open companionway hatch and one on the v-berth bulkhead--do a great job of keeping the whole boat comfortable on a hot still night.
That's good to know your experience ona quantitative level. Though I am wary of installing a second fan over the v-berth because of the noise of having a fan 24" from my head...

What do you think of the attached ducting plan, and photo of the heater/settee cabinets/v-berth? There are 4-5" 12V fans that are basically silent, and I assume it wouldn't take a lot of airflow to dry out the v-berth. This would have the dual effect of getting more warm air from the cabin heater up there. Do you think the theory correct? This design is based on my novice understanding of the moisture problem.

Boat ducting plan.jpg
IMG_4098.JPG
 
Dec 2, 1997
8,709
- - LIttle Rock
Though I am wary of installing a second fan over the v-berth because of the noise of having a fan 24" from my head...
You're waaaay over-engineering it. All you need are 2 simple 6" oscillating fans that can be connected to your 12v wiring (see photo for example...you can find 'em all over the 'net. That one one has a "cigarette lighter" plug, but anyone as capable of over-engineering as you are shouldn't have any trouble wiring it to a 12v circuit)--one hung near the companionway hatch, the other at the end of the v-berth You don't put it over your head ...it should be on a bulkhead at the aft end or or hang from the overhead just aft (oops, FORWARD) of the v-berth. And the hatch over the v-berth should be open. They'll do a dandy job of pulling air through the entire cabin.

fan.JPG
 
Last edited:
Nov 15, 2015
268
J J/30 Seward, AK
You're waaaay over-engineering it. All you need are 2 simple 6" oscillating fans that can be connected to your 12v wiring (see photo for example...you can find 'em all over the 'net. That one one has a "cigarette lighter" plug, but anyone as capable of over-engineering as you are shouldn't have any trouble wiring it to a 12v circuit)--one hung near the companionway hatch, the other at the end of the v-berth You don't put it over your head ...it should be on a bulkhead at the aft end or or hang from the overhead just aft the v-berth. And the hatch over the v-berth should be open. They'll do a dandy job of pulling air through the entire cabin.

View attachment 137599
Ah I see. Thank you for the tip.
 
Jul 12, 2011
1,165
Leopard 40 Jupiter, Florida
Rather than hard-wiring a small 12-volt fan, as Peggy suggested, I replaced an existing light with a 12-volt plug as shown below. I can then use those cheap 12-volt clip fans with the 'cigarette lighter' ends and plug then in. As an added benefit, I have a good place to charge my mobile phone without an adapter. These little receptacles are dirt-cheap, and are fused. The cheap car 12-volt fans won't last long in a marine environment, but compared to the $100+ marine-grade ones, I can go through a few before breaking even. Also, I don't have to splice wire to install or relocate one.
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
Rather than hard-wiring a small 12-volt fan, as Peggy suggested, I replaced an existing light with a 12-volt plug as shown below. I can then use those cheap 12-volt clip fans with the 'cigarette lighter' ends and plug then in. As an added benefit, I have a good place to charge my mobile phone without an adapter. These little receptacles are dirt-cheap, and are fused. The cheap car 12-volt fans won't last long in a marine environment, but compared to the $100+ marine-grade ones, I can go through a few before breaking even. Also, I don't have to splice wire to install or relocate one.
You can also put a light in there, so you don't lose the original function.
Day: Fan. Night: light.
Or for both, use a double adapter. Or a USB fan. Or a USB light.
image.jpeg
 
Last edited:
Dec 2, 1997
8,709
- - LIttle Rock
Seems to me that night time is when you'd need air flow to cool off a stifling cabin a whole lot more than you'd want a reading light that adds heat.
 

MitchM

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Jan 20, 2005
1,011
Nauticat 321 pilothouse 32 Erie PA
check out the programmable Caframo 12v fans. we have 3 on board, 1 in each cabin and 1 at the dining settee . the fans are 2 feet from our heads when we sleep; they are very quiet. they can be programmed for 2 4 6 8 hours and 1 2 or 3 speed. they're expensive at $100 but worth every penny. i'd stay away from cheap made - in - china auto store fans; they are noisy and have been known to cause fires due to wiring design inadequacy.
 

Bob S

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Sep 27, 2007
1,771
Beneteau 393 New Bedford, MA
It's been suggested before that 12V computer fans work well.
 
Nov 15, 2015
268
J J/30 Seward, AK
It's been suggested before that 12V computer fans work well.
That was what I thought to use in my schematic that I previously posted. The nice thing about computer fans is that they can be very cheap and virtually silent. "Silent" as in actually silent, not silent for marine fan standards.

In fact it was the silent and low-profile nature of my design that was the motivation to do it in the first place.