Hot!...those were the days!....the only time I have been hot on a boat in the last couple of years has been in France.
Our last NB got very hot in summer, and having one side hatch, for some reason always ended up with it on the towpath side. This is one reason we had two side hatches in NB Earnest, on opposite sides. Although NB Earnest has mostly bus windows with top hoppers, they come out easily and I got our fitter to make special corner blocks to store them, if I wanted to remove them.
The hottest we have ever been was one glorious summer in the 90's, well in to the 30's. We were at Sheffield Basin and when we came back from the air-conditioned cinema, we came back to a closed up boat! It was then total hopper removal, all doors and hatches open for a couple of hours until we could stand it back on board. Not as this mattered, as we simply sat around outside, having an impromptu drinking session with the other boaters present!
The barge has the cabin painted a light colour to reflect the heat and all of the windows are Worcester "S" type, where the glass can come right out. I will eventually make up some fly screen inserts to fit the window apertures. The wheelhouse is double glazed an has a drop down front screen as well as rear doors in addition to the side doors. It also has a fair sized dogbox to help with airflow, this is double glazed to stop condensation and heat loss as well as to cut down on heat transfer from the sun. One of the double screens is a fly screen. We also have one of the side vents / ducting that is easy to connect to our portable aircon unit.
If the bloody thing ever leaves Ireland and gets to France, some of this might be useful!