Hi.:
I sail in Florida- day time temps around 90F (32C), night
temps 80F (27C), and relative humidity around 70%. In day
time I anchor astern, that keeps the boat cool (and
confuses a lot of sailors), but at night I turn the boat
around and anchor off the bow. (for safety)
I have a mosquito netting for the hatches to keep those
critters out and there is enough air to come through the
boat. I never thought of having a ventilation problem.
Wilhelm, V-257