This must be done because the board will be shaped from 1 lb foam with no stringer. Therefore the blank will literally be a limp noodle. At times you feel like a dog chasing your tail trying to hold the rocker. You spend endless hours laying the rocker out to perfection on a piece of masonite. Then you cut the masonite to create the hotwire guide. You hotwire the blank as clean and perfect as possible, then the blank flops around like a noodle.
When it comes time to laminate (glass it) the weight of the epoxy alone bends the blank. Due to the length, it takes 3 adjustable height shaping stands to bend the blank back into the correct rocker during lamination. This is when that rocker stick get used.