: Can any one tell what the standard size is for a small cockpit and does that
: include the 3/4" lip (or not)? I have heard that Seda small size is
: 16" X 29" and that sounds good to me, but does it include the
: lip? Any advice on size, I am 5' 10" and 145 lbs building an 18' sea
: kayak. Thanks!

Since 16" would be very narrow for the outside dimension of a cockpit. I suspect that these are the inside dimensions. The outside dimensions would be more like 18" x 31", which would make this a "large" cockpit, rather than a "small". For example, VCP's Ocean cockpit - which is about as small as it gets in commercial boats - is 18" x 21" outside dimensions and ~15 1/2" x ~18 1/2" inside. This is the size of a standard #1 spray skirt. The Seda cockpit would be a #3 or #4.

Your best bet is to find a cockpit on a commercial boat that suits you and duplicate it. However, before you do, make sure that skirts to fit it are readily available.