I got a few responses to my attempt to start a rocker war. Jay suggested using Nick's proposal.

From Jay: "You could also look for the point where the depth is 50% of the distance between the DWL and the baseline, then measure the relative distance of that point from the ends vs the distance from the ends of the lowest point"

Nick added: "This would be a dimensionless ratio (distance to 50% point/distance to 100% point) where smaller number indicate less rocker. An advantage of a dimensionless measurement is when you scale a boat up or down, the measurement does not change."

Mike's Comments:
1) This might be easier to do during the design stage than measuring an completed boat. Especially determining the DWL.
2) Do you come up with 2 numbers, one for bow rocker and one for stern rocker, or do you add the 50% lengths for bow and stern and then divide by overall length?
3) Is the overall length measured from the DWL or the actual end of the craft?

I'm thinking that if I have a 16 foot boat that draws 5 inches below the DWL, I would find the waterline length at 2.5 inches. Lets say that the 2.5 inch waterline ends 18" back from the bow and 12 inches in from the stern. Is this my equation?

(1.5 feet + 1 feet) / 16 feet = .156

or is it (assuming max draft is at center of boat):

Bow rocker = 1.5 feet / 8 feet = .1875 and

Stern rocker = 1.0 feet / 8 feet = .125

Thoughts please. If we can decide how to use this approach, I'd be interested in having people measure a few boats and see what sort of results we get.

Mike