: You're right that the draft of the boat needs to be taken into consideration
: to understand the underwater shape of the hull. In line with keeping it
: simple, why don't we say, "the draft of the boat is 5 inches and the
: rocker number (RN) is .156 or some other similar value." This
: expresses how fast the underwater lateral area dies out as we move towards
: the end of the boat.

in this case maybe the proportion of draft to depth is more important unless you see the yak, draft does not give and idea of the most basic curve proportions (width and depth)

but in response to nick's and what you're saying:

it is actually a really nice way of estimating the lateral plane coefficent. it gives 3 points of a curve and if it is even close to giving an idea of how manouverable a yak is - like a long yak w/ the same lat. plane coef. as a short yak same load has something similar turnability, then i now say go for it!

(for me, i have a preconceived notion that rocker gives a shape idea, but i like the one above too. if i knew the length and depth(and usually would to get the figure anyway) then everything is covered as nick says anyway)

-mick