: There must be a happy medium between enough and way too much. I went with the
: 3/8 because of the with of the lip (3/4" ply) I put 10 pair on the
: forward hatch spaced somewhere between 3-4 inches.( I also put washers
: behind the magnets in the lip to increase the force on at least half of
: the pairs.)

Tell me more about this.

:There is a 4mm spacer between the lip and the deck.

4mm space then between the magnets?

: With the
: gasket compressed enough to make the hatch flush with the deck, the hatch
: still popped off easy enough.

How thick was your gasket originally? Ted Henry's (Holly's, actually) Silver used some soft 1/8" thick gasket material that compressed down to 1/16" or less and brought the magnetic fields in close proximity. He also had only half the magnet contact the hatch lip..I think Rob recommends this? You get an edge biting into the foam, and half the volume of foam to compress.

: Too easy. I could envision something banging
: around in there whilst upside down and knocking the hatch loose.

I see that too. I'll have a provision in my deckline or for internal bungies to keep the hatch on while in rough water and gear in the compartments.

: It is nice to let the hatch loose and not have to worry about it going
: anywhere. When I get the time I'll add some magnets to the rear hatch.

How do you plan to do the retrofit? I'm thinking of retrofitting magnets into my Guillemot.

: Possibly using a thinner spacer or no spacer at all to get the magnets closer
: to each other might help make it stronger.

Absolutely. I think the force varies with the square of the distance.

Shawn