: Most of the volume in a kayak is in the middle, since it is generally the
: widest, tallest part of the boat. "Popping up" the cockpit area
: will increase the overall volume substantially, eliminating much of the
: advantage of the low volume.

Increasing the volume by widening the boat will certainly make it harder to roll, but will making the cocpit higher have the same effect? It would seem the tall, rounded cockpit area would help the first half of the roll (upside down to halfway up)when it is submerged. It should be irrelavent for the rest of the roll, when only the hull is in contact with the water.

Also, lowering the volume by flattening the decks would create a form that would be more stable (and harder to start rolling) when upside-down, wouldn't it?

Anyway, for a given boat length and volume, the minimum height boat must be the maximum beam boat, and thus harder to roll.