Ron, while I'm a staunch advocate of no hatches (this was a major factor is the sinking of the Edmund Fitzgerald) and no bulkheads (these were major factors in sinking BOTH the Edmund Fitzgerald and the Titanic), I see people who do like them. Let me provide some observations on fastening things down. They come from motorcycle experience.
On my dirt bikes, I always had a rack on behind the seat. There, I would carry lunches, rain coats, and various other pieces of gear. I NEVER lost anything that was fastened down way too good. I did lose things that were fastened adequately. Here's what I learned.
There are two, basic ways of fastening something down. One uses a rope/chain/cable that is non-elastic. You tighten these down and they do a nice job of restricting the furthest limit of travel of an object. But, they do only a mediocre job of holding an object close to its mooring base, in your case, holding a hatch to the boat.
The other method is to use a bungee-like strap that is elastic. These do an excellent job of holding objects close to its mooring, but do a lousy job of restricting outer limits of travel in a bounce.
The only way I found that was reliable was, to fasten an object down first with bungees to snug it in tight. Then. lash it with rope to absolutely limit outer travel. The combination of something elastic, and something non-elastic did the trick.