I believe that all boats under 20' are required to provide "upright and level flotation", i.e., the gunnels would be above water if you drill a hole in the bottom and let the boat settle gently. All Grady's under 20' meet that requirement.
I don't count on the "upright and level" provision. I suspect that if I get in that much trouble, it's likely that the seas are big enough to roll a boat sitting so low in the water.
When the old 'Powerboat Reports' was still in publication, I would occassionally read about recalls because the Coast Guard pulled a rare surprise inspection and found that some manufacturers (not Grady and typically not any highly regarded brand) were not putting in enough foam.
Grady goes one step beyond the legal requirement and states that all boats over 20' have 'basic' flotation, i.e., some portion of the hull will be above the waterline, but not necessarily "upright and level".
Rob