: What is the rough industry standard for the dimensions of the cross-section
: of the cockpit coaming? I am thinking of 3/4" from the underside of
: the lip to the deck, and also 3/4" from the outside of the vertical
: portion to the outer edge of the lip. In other words, the groove that the
: skirt edge fits into is a 3/4" square. Is that about right?

Hi Jon
I think 3/4" would be fine.
I made my last coaming less than that,and my neoprene spray skirt does not fit as well as it should. I don't have one but, a nylon skirt might fit OK. 3/4" should work with all.
Best of Luck Terry