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Catalina/Capri 25/250 Sailor's Forums

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Effective AC on a boat?

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Initially Posted - 12/29/2010 : 06:07:05

So, I've spent the last three weeks in SE Asia in the winter, theoretically it's "cooler" now, but man, it can kick your butt when the sun comes out (rare in monsoon season). On the couple of days the sun actually came out, and we were outside, I literally felt faint and couldn't wait to get back inside somewhere with AC & cold water. Which brings me to my question:

Is there an effective AC solution for boats in a tropical climate? Ideally it'd be powered by something (relatively) easily replenished, which means no generator, I'm thinking more like a substantial battery bank separate from your normal ship's power & starting banks, charged by solar/wind turbine. The only time you'd really need it would be in port, assuming there's enough wind to sail with in between ports, you'd have enough wind to keep you cool enough to sleep. The problem with that is you tend to spend more time in port than you do underway, so you'd be depleting your banks, possibly with no easy way to replenish.

Now, admittedly, I'm right on the equator, and currently up a few stories in my brother-in-law's apartment in Singapore, and it's actually quite cool (comparatively) right now at about 9pm. We're quite close to the beach, so there's a nice breeze off the Singapore Straits, which would probably be OK to sleep in if a bit hot. I just wonder how folks who do the pineapple cruise manage the heat & humidity if they didn't grow up with it?

I know some of you guys in Florida/Texas, etc. have generators to run your AC overnight while you sleep, but this seems like a good short term solution, not a long term one. I'd hate to have to carry fuel simply to cool my sleeping quarters, but I'd be willing to go out of my way to put in a rechargeable system of batteries & charging options to do so. Obviously you'd have to charge your cooling array as a tertiary load, behind starting & house loads, so you might not always have the option to cool if you've had little wind or sun to charge your primary & secondary systems, but it seems workable, I think.

I'm thinking even if you only managed to cool one small compartment on the boat (like the master suite), you'd have some place to go to escape the heat for a while and hopefully sleep.

I haven't done any research on this, but I remember a thread a while back about it. I'll look it up when I get home (flight back to Seattle is in about 11 hours).

Thoughts?

David
C-250 Mainsheet Editor

Sirius Lepak
1997 C-250 WK TR #271 --Seattle area Port Captain --

Edited by - on

GaryB
Master Marine Consultant

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USA
4304 Posts

Response Posted - 12/29/2010 : 10:18:48

A Honda 2000 watt generator and some extra gasoline would be a lot easier than installing a battery bank and a wind turbine/generator.

Unit will run 4 hrs on 1.1 gals of gas at full load or up to 9.6 hrs at 1/4 throttle. 53 to 59dB and will charge a 12v battery at 8 amps.

At full load running 8 hours a night you could be cool for 4 nights on less than 10 gals of gas.

EU2000i Specifications
Engine Honda GX100
Displacement 98.5cc
AC Output 120V 2000W max. (16.7A) 1600W rated (13.3A)
Receptacles 20A 125V Duplex
DC Output 12V, 96W (8A)
Starting System Recoil
Fuel Tank Capacity 1.1 gal
Run Time per Tankful 4hrs. @ rated load, 9.6 hrs. @ 1/4 load
Dimensions (L x W x H) 20.1" x 11.4" x 16.7"
Noise Level 59 dB @ rated load 53dB @ 1/4 load
Dry Weight 46.3 lbs.
Residential Warranty 3 Years

Edited by - GaryB on 12/29/2010 10:19:52

Voyager
Master Marine Consultant

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USA
5378 Posts

Response Posted - 12/29/2010 : 10:37:23

David
A few physics-based cooling techniques discussed were:

(1) Evaporative cooling - whenever something that's wet evaporates, it cools down - basic physics. On camping trips we kept drinks cool by rigging a burlap sack with a pail of water wicking down the sack to cool its contents.
Or you can use a fan to blow across a wet porous membrane to cool the air. This is most effective in dry, hot climates like deserts or the dry side of an island. It's least effective in hot, humid spots like Singapore. A rag soaked in ice water on the forehead and wrists is probably more effective there.

(2) Redneck AC -- Someone proposed rigging an ice chest with plastic tubing and using an old Camaro heater core with a small pump and a fan to create a simple air conditioner. Theory was you pass water through the tube in the ice chest, then pump the cold water into the heater core (heat exchanger). The fan blows through the heat exchanger and produces cool air. Only problem was that an AC engineer calculated you'd need something the size of a small iceberg to produce enough cooling required to take a 90 degree cabin down to 75 degrees. Dry ice, if available, would require anti-freeze in the tubing. No idea how much you'd need.

Other options not discussed are:

(3) Some hydrating packs can be filled with cold water and worn against the body to cool you.

(4) Others have produced gel skull-caps that you put in the freezer before you put them on. That would cool your head on a hot day.

(5) Coleman, among others, sell an electric cooling plate that you can put into a cooler to cool down your drinks or food. They claim at they can reduce the temperature as much as 20 degrees F below ambient temps. These run on approximately 4 Amps at 12V. That means, if ambient is 90, you can cool down to 70, or if ambient is 70, you can cool to 50, which is pretty good for keeping food fresh for awhile.

Now, if you have a battery bank with two group 27 batteries, you can run one for about 20 hours before you have to recharge the batteries. If you have a wind generator that can produce 10-20A, you can run several indefinitely while the wind is blowing.

I'm not sure whether you can sit on them or lean back on them, but they would keep a wet towel cool enough I'd guess....

I'm sure that inventive sailors have come up with other ideas.

Edited by - on

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 12/29/2010 : 19:40:36

After one weekend of trying to sleep in the aft berth using towels to dry off every few minutes, persuaded us to install A/C

When alongside with power, it's a none-issue.

When on the hook, we run our Subaru Robin 1760watt generator. It has a auto mode that drops the fuel consumption when the A/C compressor turns off (leaving just the fan running, I'm pretty sure the pump turns off too)

So the Robin powers the A/C for a full night (ok, from about 11pm till about 6am) on 1.1 gals, not a lot of fuel.

The A/C unit keeps the boat frosty

I have marked the temp control with a 'ideal' band so that we can get into the comfort zone pretty quick. Even then the Admiral is likely to ask 'turn it up' or 'turn it down' ... wish I had a remote for the A/C controller

[url="http://robinamerica.com/pspecs.aspx?pid=74"]

[/url]

Oh, and 'silent' is really not the right term to use in their description! But I guess it is compared to our home unit!

I place the geny on a foam paddle board so that the exhaust faces overboard at the stern ladder. The height is just enough to warm the ladder step just a tad to much. I have a piece of sheet aluminum that I'm going to clip around the step next use. (Don't think we'll need it this weekend

Paul

Edited by - on

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 12/29/2010 : 21:09:48

The generator is around 60 decibels. How loud is the air conditioner? Together, can you tune it out?

Edited by - on

Voyager
Master Marine Consultant

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USA
5378 Posts

Response Posted - 12/30/2010 : 11:40:52

Noise cancelling earbuds!

http://www.amazon.com/Philips-HN060-37-Noise-Canceling-Earbuds/dp/B00061IYJC

Edited by - on

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