How to quantify rocker?

[Neil C.]

Dumb question of the week:

How do we put a figure on the amount of rocker a particular boat design has? Obviously the actual keel-line will be an uneven curve, with different designs having a different profile. However, there is often a figure quoted for "overall" rocker level. How is this measured? I'm going to hazard a guess that if you put your boat on a flat floor and adjusted the pitch such that the distance between the stem and the floor equals the distance between the transom and the floor, that figure is the rocker. Is that right?

[Clive Everest]

As a single figure of merit that is how I quantify it, with a extrapolation across any further rounding at the bow.
If you want  to be a bit more specific the curvature on my rocker line increases linearly from the transom where the radius of curvature is 68m to the bow where the radius is 15m.

Clive

[ade white]

Yep rocker is an interesting form of measurement. (back many moons ago) ... I used to own a fireball. 11218, called Armitage Shanks. It won the worlds back in 79ish (i think) in the hands of Laurie Smith and builder/crew at the time, Tom Baker. The point I wish to make though, was... It had a nagative rocker for about the last meter towards the transom and it was an amazingly quick boat. (interesting the measurement perameter variations in 1 design).
Last time we sailed it was when Deb was pregnant with Joe. We often used to beat, the then, new winder boats.. sold it when Joe was born so thats 14 yrs ago now. 'How time flies!'