An interesting idea; the only potential problems that occur to me are these. First, for you saltwater types, one would want to check any metal parts and be prepared to replace the latches when necessary. Second, I can imagine the first time you find unexpected fog and rely on your compass, which is eight inches from the magnetic catch....

: There's a certain individual who used to frequent this board who came up with
: another interesting method: child-proof latches for cabinets that are
: available at Wal-Mart for $6, if I remember correctly. They are opened
: with a magnet, so you would have to keep your magnetic 'key' handy (maybe
: on a cord in your PFD pocket). This method wouldn't use internal bungees.
: You would push the hatch cover down onto the foam seal until the latch
: catches. When you unlock it with the magnet, the compressed foam would pop
: the lid up.

: Dean