Hello riverman, you wrote:

John Kuthe...

The torque to rotate the boat to upright does not come from the
paddle, if the roll is done correctly, ergo the aeration of the
water is inconsequential.

riverman...

Good point. Is there any value in practicing a roll by suspending a
kayak between two trees with ropes tied to the ends, and learning
to twist it upright with hip snaps alone?

http://www.qajaqusa.org/Technique/ropegymnastics.htm

http://www.dubside.net/qajaasaarneq.cfm

Finally, a small comment about "bombproof" rolls...

Even after many years of hardly ever missing a roll when I really
needed it, I'm still wary of the "bombproof" concept. After all, if
I'm paddling along and a bomb is dropped on me, trying to roll back
up would probably be a moot point. Serioiusly though, while we
can--and should--constantly practice our rolling and other
self-rescue techniques, I think we might ultimately be doing
ourselves a disservice by convincing ourselves that we can develop
rolls that will, without doubt, always bring us up under any and all
circumstances. Overconfidence can really harsh one's mellow at just
the wrong moment.

Perhaps the most dangerous thing for anyone--in any field of
endeavor--is to feel that they've entirely "mastered" anything. For
one thing, life would be terribly boring if we ever got to the point
of being able to "duplicate perfection" at every turn, with nothing
more to learn (define "repeatable perfection", after all). When it
comes to self-rescue skills, convincing ourselves that we've actually
perfected a technique to the point of "bombproofness"-or perhaps more
appropriately "foolproofness"--is a fools game that could just turn a
fine paddling day into a tragic day.

No matter how good you are, only "beginner's mind" will help you get
better.

--
Melissa