@Peter I know what you mean, but I'm about the ones that are on sides at pedestals of fore- & aft light cranes. Those are always "open".

Are those Grey things ..Not counter weights for the Cranes???

What I find interesting are those grey bulkheads. Earlier on photo of a Rickmers' ship of same design I thought those are opened hatches... Maybe they serve to separate containers from awkward deck cargo in the middle?

Form follows function. Heavy lift cranes, & I like the offset bridge position with the (!) promenade deck below it ;-)
The lattice work on the accommodation front is dual role: a cell guide (if you expand the photo & look carefully) & it offers protection from the crane spreader/container too. Something different and a good shot too.
Thanks & regards, Rick

This ship is... strange in her arrangement.