: I am beginning hatch construction on my latest boat and I will be
: using rare earth magnets.

I've done a couple of magnetic hatches for customers over the years and never really cared for them. Unless you have a paper-thin gasket material you have to use a ton of magnets..

I've been using internal bungees exclusively for wooden hatches for the past 4 years and haven't looked back. With carbon fiber lips, padeyes and hooks they are virtually water tight and so much easier and cheaper to construct.