They're the same as these on the over head hatches. They're strong enough and they don't come un-latched. I can't see how water(pooped for instance) could get enough of a grip on the lids to overwhelm the latches.

If I was preparing for crossing an ocean, I'd probably add an additional padlock like hasp, or two, and just use some sort of clip to keep it closed.

I've seen a few arrangements in a few wooden boats with more positive locking mechanisms. One of the easiest I've seen is a simple but strong below deck turn that locks with a piece of flat steel or bar. Those were turned by a large screwdriver or similar so all you saw was a metal round with a slot in it. Nice idea.

What are your cockpit lids like on your Caravelle, Jay? Your cockpit is fiberglass, right?