Gord has it! We have used DampRid. It will only work in a closed space so we have all hatches tightly closed and small fans running to circulate the air. Calcium chloride is a non-volatile salt
that picks up a lot of water
to the point where it becomes a liquid (solution). It has worked for us over several months in Ft. Pierce, Fl. A dehumidifier would be a better solution but you would have to rig up a way to drain the water
from it unless you buy one of those big, expensive, energy eating dehumidifiers that are used for basements, etc. They have a pump to pump the water out.
By the way, Calcium chloride was a major component of the salt
spread on roads. The disadvantage is that the resulting aqueous CaCl2 solution is slightly acidic and hard on cars so I think they've pretty much taken it out of road salt. With the DampRid containers the acidity is not a problem. And when I say slightly acidic I really mean slightly
. I just did a quick check for some chemical parameters of calcium ions and didn't find what I was looking for, but it is going to be less acidic than regular white vinegar.