The hatches in the Coronado are really huge; and ours being from acrylic or some similar material, they were a source of constant cold during the winter.
So just like with the main hatch we did the same with the two hatches in the aft cabin and V-berth: we put in foam inserts, for which the Wife sewed a water-proof cover. We stick the cover into the hatch while it is especially cold outside and prevent possible draft this way.
What you see in the photo below is the red foam insert pushed into the hatch, and an additional bug net over the hatch. This bug net is also a home-made thing; all four edges have Velcro sewn to it and there ain't no spiders entering *this* way! We leave this bug net attached year round, although of course its summer time when we laugh at the bees and flies that can't enter.
The foam inserts drastically increase the temperature in the V-berth in the wintertime and give us the choice of adjusting the temperature rather than acting at its own will:-)
There is also no condensation on the hatch, if the insert is in the hatch.
