Re: Hatchway alternatives?
My boat has a single piece of smoked plexiglass-like stuff.
Ironically, I have been planning to replace it with a three-section wood hatch. I think three pieces would be easier to stow underway. I also might make the middle or top section replaceable with a clear piece so I can see out if I have it closed while inside (I rarely sleep aboard.)
That said, I don't think the difference between four pieces and one piece would make an appreciable difference in an emergency evacuation. Whatever difference in time there might be would be easily outweighed by the general situation down below: are you in the V-berth, the head, the rack, etc?