: Rob Macks' magnet idea is very slick. He seems to have worked out the
: corrosion problem. But they still make me nervous. Magnetic forces
: decrease with distance. This means that if something should start to knock
: the hatch loose it will tend to keep on going. I think Rob probably has
: enough magnets to hold in most situations, but I have had my boat be
: knocked pretty hard going out over surf. Magnets don't like shocks. While
: a leash will keep you from losing the cover, getting a hatch full of wave
: could ruin your day. I would like something a little more bomb proof.

The magnet size and placement I now use holds the hatch very securely.

You must lever your fingers against the deck under one side of the hatch cover
to start to dislodge the force of a couple of the magnets and pull firmly to release
the cover. Many people don't have the finger strenght.

The internal lip makes the diameter of the hole smaller so any gear pressing against
the hatch interior will distribute that force over more magnets.

Any shock associated with running through waves will apply downward forces as the
hull hits the water surface after cresting a wave. This will not apply force to dislodge the magnets

I'm confident that the hatches will stay in place.

For someone who likes the magnet idea but wants more security, you could make
a latticework 1/8" plywood insert to lock/snap under the hatch cover lip to ensure gear
cannot dislodge the magnetic cover.

Under real extreme conditions there are no guarantees.

Fastex snaps and shock cord hooks can fail too.

Rob