First of all, apologies as I imagine this has been covered but I can't find anything in my searches. Probably I am using the wrong terminology.
So first off, what do we call the covers that close off the compartments in the cabin, compartment covers, hatch covers, what is the right term?

Secondly, how to keep them in place when the boat is heeled. I don't have cushions over them so I thought about screwing them down but that restricts access. Maybe Velcro but then they wont seal good but maybe that's good for ventilation? Maybe a clip on one end and a fastener that you turn 90 degrees on the other end but of course like every other piece of stainless I buy for the boat I'm sure they are pretty salty.
What is most commonly done when the covers are open and prone to sliding about?
So first off, what do we call the covers that close off the compartments in the cabin, compartment covers, hatch covers, what is the right term?

Secondly, how to keep them in place when the boat is heeled. I don't have cushions over them so I thought about screwing them down but that restricts access. Maybe Velcro but then they wont seal good but maybe that's good for ventilation? Maybe a clip on one end and a fastener that you turn 90 degrees on the other end but of course like every other piece of stainless I buy for the boat I'm sure they are pretty salty.
What is most commonly done when the covers are open and prone to sliding about?