Bruce, great photo. I’ve never seen it. GG’s carbon edge boards were starting to approach mats in their ability to flow and give, and you can kind of see that in the track. Some people think his edge boards were finally just mats you could kneel on.
You can see the divergence between Greenough and the sport of kneeriding in the principles Dale took down during conversations with him. They apply to the velo-type spoon, not necessarily to the later edge board:
#1 - The thinner the board, the better the feel and the general surfing.
#2 - The template is based on a foil outline with the trailing edge cut off, giving a bullet shape.
#3 - It is good to keep the last 18-24" of template and rocker straight; a curved rear template is not necessary because the flex gives variable shape and maneuverability.
#4 - A hull’s rails are 1.75-2.0" high at the mid-point.
#5 - A spoon’s flex (twist & rocker) goes up to about the center (mid-pt).
#6 - The tail must flex and torque or it will stick and track.
#7 - Flex at the tail is about 1.5" when hand bent but sometimes 5-6" on a wave.
#8 - The last 6" of the tail corners are solid glass.
#9 - It is important to get enough glass on the deck side where it breaks.
#10 - 10+ lb spoons are common.
#11 - The fin is 10" deep, flexible, about 6" x .75" thick at the base, with the back of the fin base placed approx. 5" from the tail; use a 5- or 6-1 base-to-foil ratio.
#12 - The fin is made of unidirectional roving, one-way strands; saturate, place in female mold with matching male insert as cover, and jack up a vehicle over it to squeeze out the excess resin.
#13 - Most of the flex is in the top 25% of the fin.
#14 - The trailing edge of the fin is finished with a 2-3 mm sharp flat along the entire length.
#15- Faster speeds require thinner fins in both template and cross-section.
#16 - Maximum speed is achieved by the lowest possible center of gravity; all weight in construction should be lowered and centered.
#17 - Provide optimum surface texture by finish-sanding with 400 wet/dry; a surface that is rougher or slick will create turbulence between laminar flow layers beneath the hull; same treatment for the edges above the waterline – NO WAX.
#18 - As speed increases, drag increases; boards with displacement hulls need a .005 mm surface most of all.
You have to ask, what common ground is there between these guidelines and the ones followed in current kb construction? One of the best shapers, Bruce Hart (Flashpoint), has experimented with a foam/glass hybrid that incorporates some of these principles but the spoon design sort of defies assimiliation.
More to say, out of time…