"displacement hull" edges

For the hull gurus out there, just wondering where/if hard edges are placed on a displacement hull? looks like most seem to start behind the fin where bottom becomes flat, what have you had most luck with???

anywhere in the last 18" or less in tail area, depending on what you want the board to do....

Even though Geoff McCoy’s boards are not “hulls” like Greg Liddle et al they do have some characteristics in common.  In this short video via this thread

http://www2.swaylocks.com/forums/geoff-mccoy-surfboard-design-theory

he talks a fair bit about single fin boards w/ soft rails but hard edge in tail.

 

McCoy Surfboard Rails

http://www.youtube.com/watch?v=6eSqc0T5QNs

Varies with the board for me. I like my longer ones (7’-above) to have the hard edge starting about 10" up from the tail or right on the tail. Shorter boards, I like the hard edge about 18 -20" up but it doesn’t seem to drive as hard and it gets skittish unless you have some sidebites during a rail turn. It does make a top turn easier tho IMO. The longer you ride hulls, the more selective you become on what works for **you. ** Everyone varies. Good luck!