Corey
Just as the CE, Centre of Effort, is the geometrical centre of the sail, the CLR, Centre of Lateral Resistance, is the geometrical centre of the underwater profile. On very regular shapes, such as triangles and rectangles, it is easy to find their centres, just by drawing the right lines (see a math book on this). However, the method with balancing the sail or hull profile on a ruler is much more useful with irregular shapes. You could even find the geometrical centre of Texas (.. or Pennsylvania ...) using this method.
Just remember that the actual CP, Centre of Pressure, in a sail is not quite the same as the CE . The CP will move a bit around depending of the setting of the sail (angle of incidence etc.), and will generally sit somewhere forward of the CE. Likewise, the CP of the underwater profile will sit somewhere forward of the CLR. All this means that guessing on the Lead , the distance of CE forward of the CLR, can be difficult and lead to surprises (too much weather helm or lee helm).
On a dinghy it is normally a forgiving business. Dinghies generally have huge rudders (relatively speaking) compared to the rudders of a ten ton cruiser, so a bit extra weather helm can be controlled by the rudder without big rudder angles needed.
Arne