"cvj" wrote in
:

Since we do not need to look through the hatch I am wondering if I
could reduce the condensation by either a) paint the hatch window with
a glossy white paint to reflect the incoming sun rays or b) glue a
layer of aluminum foil on the inside of the acrylic.



The problem is that when the sun sets, the hatch gets colder than the air
in the boat, causing the same condensation problem you get sitting a
glass of a fine single malt Scotch and ice on a table. The air in a boat
is like a swamp, especially at night being all open like they are on the
surface of the water. So, instead of trying to regulate the sun, that
will do nothing constructive. Now, what we need to do is to keep the
warmer cabin air AWAY from the cold hatch so the condensation cycle and
the convection airflow feeding it (cold air from the hatch dropping,
replaced by warmer air sucked in across the overhead rising) more warm,
moist air.

A nice styrofoam block cut to fit tight into the hatch opening will
insulate the cold of the hatch from the warm of the boat. Costs almost
nothing and comes out easily so you can use the hatch when you want to
open it. If the boat has air conditioning, it also saves a few thousand
Btu blocking the hot sun in the daytime from heating up the air and
whatever the sunshine was cooking like the expensive woods if the hatch
is transparent. Go see the hobby department of any WalMart or one of
those hobby shops the women love. They have blocks in several
thicknesses cheap!

Don't feel bad, the swamp inside our Raymarine 2KW radome eats itself
from this condensation-at-night problem every year. The pot metal parts
corrode and white powder shorts out the PC boards exposed by holes in the
pot metal chassis. (I just put this in for my shadow Raymarine dealer
who loves for me to mention it on rec.boats.electronics.)...(c;

Don't forget to keep your fuel tank stored full. It rains in there, too!