I'm getting tired of kicking this horse every few months . . . here we go again. Hopefully this time you'll be satisfied with the answer.
The 21 and 25 were studied by Steven Loui (bigfluke on csc) of Navatek who used the hull as a base to design his own version of this hull.
http://www.midweek.com/steven-loui/
http://www.navatekboatbuilders.com/sea-blade.html
