Any heavy duty suspension seats

You guys have helped me before so here is another one. My buddy has a 20 ft Duckworth and looking for HEAVY duty suspension seats that can handle easy 300+ lbs. Any suggestions would be great thanks.
Pacific Northwest Fishing, Hunting, Boating, and Outdoor Cooking Forums
http://www.theoutdoorline.com/forum/
http://www.theoutdoorline.com/forum/viewtopic.php?f=4&t=2201