Passive solar cooling of your boat
 

Would this work?
Put a water soaked blanket on the deck (or over the cabin). It would
cool the surface below by evaporation in sunlight. When the water
evaporated, you'd pour more water onto it. If salt water, you'd have
to pour enough to remove the salt left behind by evaporation.

Passive solar cooling of your boat
 

On Thu, 3 Mar 2011 10:48:14 -0800 (PST), Frogwatch
wrote:

Would this work?
Put a water soaked blanket on the deck (or over the cabin). It would
cool the surface below by evaporation in sunlight. When the water
evaporated, you'd pour more water onto it. If salt water, you'd have
to pour enough to remove the salt left behind by evaporation.

Your best bet is to use enough shades and awnings to keep sunlight
from reaching the deck and cabin top in the first place.

Passive solar cooling of your boat
 

On 3/3/2011 6:07 PM, Wayne.B wrote:
On Thu, 3 Mar 2011 10:48:14 -0800 (PST), Frogwatch
wrote:

Would this work?
Put a water soaked blanket on the deck (or over the cabin). It would
cool the surface below by evaporation in sunlight. When the water
evaporated, you'd pour more water onto it. If salt water, you'd have
to pour enough to remove the salt left behind by evaporation.

Your best bet is to use enough shades and awnings to keep sunlight
from reaching the deck and cabin top in the first place.


How about installing a generator and an A/C unit? The result will be
actual air conditioning.

Passive solar cooling of your boat
 

In article ,
says...

On Thu, 3 Mar 2011 10:48:14 -0800 (PST), Frogwatch
wrote:

Would this work?
Put a water soaked blanket on the deck (or over the cabin). It would
cool the surface below by evaporation in sunlight. When the water
evaporated, you'd pour more water onto it. If salt water, you'd have
to pour enough to remove the salt left behind by evaporation.

Your best bet is to use enough shades and awnings to keep sunlight
from reaching the deck and cabin top in the first place.

Right. But evaporative cooling is a pretty low cost cooling solution.
Might be easier to attach a cloth than rig a shade on areas that aren't
normally shaded.
Evaporation works at night too if high humidity doesn't hamper it.
Whether it's practical on a sailboat is another issue.
A lightweight fabric tailored to fit and attach might be useful.
You'd use power for a pump to keep it wet.
Unless you can do that by something hung in the in water working
by capillary action.
It's going to salt up, but you can shake that out when it's dry.
You could test its effectiveness with a cheap fabric, a good
thermometer, and a bucket on a rope.

Passive solar cooling of your boat
 

On Mar 3, 7:22*pm, wrote:
On Thu, 03 Mar 2011 18:07:49 -0500, Wayne.B

wrote:
On Thu, 3 Mar 2011 10:48:14 -0800 (PST), Frogwatch
wrote:

Would this work?
Put a water soaked blanket on the deck (or over the cabin). *It would
cool the surface below by evaporation in sunlight. *When the water
evaporated, you'd pour more water onto it. *If salt water, you'd have
to pour enough to remove the salt left behind by evaporation.

Your best bet is to use enough shades and awnings to keep sunlight
from reaching the deck and cabin top in the first place.

I'm surprised a double wall construction with air flow in between is
not more popular on cabins. I do see lots of poly tarps over the boats
over at the anchorage on FMB in the summer.

In dead still air, the sun will heat the surface of a tarp used as
shade. So, although you get some relief from the direct shade, you
get no cooling effect.
The idea here is that even at near 100% RH, you can still get drying,
I know this from a childhood spent hanging out clothes in N. FL 100%
humidity. Evaporation does cause some cooling and also shades the
boat from direct sunlight too. Swamp coolers work by air flow of low
humidity air causing evaporation whereas my evaporation thing works by
adding heat to the water from sunlight. The water that is normally in
equilibrium with the air above gets a little extra kick from the
sunlight so evaporates carrying off the heat it started with.
Another possibility is a sort of "pleated chimney" that is saturated
with water. It is pleated to maximize surface area so that air in
contact with it is cooled by evaporation. The cooled denser air falls
down the chimney into the boat.
At the other end, you have a chimney of fabric that is black near the
top. Sunlight heats it causing an updraft. So, you have cooler
dropping into the boat and warmer air rising out of it thru the other
chimney giving a strong draft even with no breeze.