We have a very nice set of screen doors that replace the hatch boards.
We use these when the dreaded Black Flies make their appearance.
They were custom made and very nicely done.
Wood framed and varnished with nice mosquito screening.
Our problem is that somebody is always coming and going out of the companionway. And of course you have to slide and close the cabin top every time. The flies still end up getting in the boat.
At night, when evrybody is ready for sleep, they work great.
Allow pleanty of ventilation and keep the critters out.
Courtney is My Hero
If a man is to be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most - E.B. White