by Paul Gross

George Greenough’s evolution as a flexible kneeboard builder took another step forward in 1970 when he began to develop a narrower “edge board” design, which replaced his wide, round bottom displacement hull flexies of the mid-to-late 60’s.

The older displacement hulls were best suited to perfect point waves, over 6’. But, as those conditions became increasingly more crowded, he wanted a board which would skim across less perfect waves, and glide over flat spots with more ease.

The first edge board design was the same outline curve of Velo, but narrowed from 22” to 19 ¾”. The nose and tail dimensions (one foot back) were also changed from Velo’s parallel 19 ¼” and 19 ¼” measurement, to 17 3/4″ and 16” respectively. The length (5’) remained the same.

Edge Board #1 was shaped without a wide flat area with sharp edges. George had no idea what configuration the flat planing area should be. He wanted to experiment with the outline of the edges, using a bondo to build them up, until it felt right. The shape of the flat planing area went through numerous changes before he found the right combination of lift and turning ease.

The next challenge was to find the right fin to handle the unforgiving nature of the sharp edges. He didn’t want to alter the efficient rocker scheme of Velo (which was dead straight the last 36”) in order to free up the edges. (Thrusters later addressed the problem of sticky edges by using large amounts of rocker throughout the board. A poor solution, trim speed-wise.) After struggling with conventional, thin cross-section fins, George began to thicken up his fins, finally arriving at a 5.5 to 1 base-to-thickness ratio. This thickness allowed the nose to lead the tail in a turn, but still maintain drive.

At this point in the evolution of the edge board, Crystal Voyager was filmed (winter of 1972.) The black and white prototype edge board he rode was, at times, still problematic. The board was very heavy (due to all the bondo building up the edges) and somewhat stiff for George’s weight (135 lbs.) Occasionally the board would catch an edge or pearl. But, in the sequence of brownish, sucked out right point waves, the potential for late take-offs and lightning-quick speed is clearly there.

One thing you can see in Crystal Voyager is the front end of the board dropping out on steep waves. This was because the edges were so slippery, there wasn’t enough drag to hold the nose up into the pocket. George eventually added the small wooden runners in the middle of the edge panel, and they provided the tracking stability the edges had taken away.

The general parameters of the edge board design were finished. George’s next step was to make a mold from the heavy and stiff black and white board, and begin to experiment with different degrees of flex, construction techniques, and materials.

Mold #1

 

This is the first edge board mold, made in 1973 from the Black and White board. Many boards have been pulled from this mold, and the mold itself has gone through several changes.

Like the Black and White board, the mold was originally 19 ¾” wide. Later, George cut 1 ½” out of the width, bringing it down to 18 ¼” wide in the center. He wanted to add some stability to the board’s handling, so he modified the outline from an arc tail to a true square tail. (You can see the modification on the mold.) He also began to cut a three-pronged swallow tail into the square tail, to allow the corners to flex independently of one another. The swallow is covered over with fabric so the water would not swirl down and around the fin. The corners were very flexible, especially in later boards.

In 1975, he narrowed this mold another inch, to make several 17 ¼” wide spoons for his sailing trip through the South Pacific. The stripe visible down the middle is where he widened the mold back up to his preferred all-round width, 18 ¼”.

The grey edge board lying next to the mold is a “safety plug” George made out of mat cloth, to preserve the shape in case the mold was ever damaged beyond repair. The plug shows what a detailed and sophisticated shape he developed.

This was also the mold that George used when he began to make boards out of carbon fiber and epoxy in the early 80’s. Since the shape of the board and the tuning of the flex was already dialed in, he was able to immediately use the new material to it’s best advantage…which is to cut out some of the weight (because carbon fiber is stiffer, it took fewer layers to arrive at the same flex) and to eliminate the fatigue factor of conventional fiberglass and polyester resin. (Carbon fiber doesn’t wear out when repeatedly flexed, although it will break, with no prior warning, if it bends too far.)

Eventually, George was making carbon fiber spoons with epoxy in a vacuum bag, and the resulting weight was around 6 pounds, minus the fin. None of the bagged boards ever broke, in spite of their light weight.

Most of the “post-Crystal Voyager” edge boards George is riding in photographs and films is out of this mold.

Mold #2

 

This is a 5’ x 19 ½” wide edge board mold. The shape was made directly from George’s outline and bottom curves. The plug and mold was constructed by Paul G, under George’s close direction. The middle edge panel is the same width as the center section in the original 18 ¼” mold. The rail sections were each widened out 5/8”.

Mold #3

 

This is George’s “Camera Board” mold. 5’4” long. It was designed for filming while riding tubes. The added length and wider tail area was intended to compensate for 30 pounds of 35 mm camera equipment and batteries. Only one board was ever pulled from this mold.

Mold #4

last spoon

Another 5” x 19 ½” mold…very similar in concept to mold #2. Also made under George’s direction by Paul. You can see where the nose width was narrowed along the first foot of the mold, after the first board from the mold proved to be a bit wide up front. The black material in the nose area is epoxy flashing left over from the last spoon George ever made for himself, in 1990.

Mold #5

 

This was a shape which was a subtle modification of the design from mold #1. The back of the tail block is 1” wider. This was George’s small wave spoon, and ultimately the board he rode most frequently in the late 80’s.

Mold #6

 

This shape was an attempt to get a wider, “Velo” feel to an edge board. The center panel is the same width and shape as the original edge board mold, but the rails were widened out to make a board 21” wide. 5’2” long. It was good in smaller waves. Shaped and molded by Paul, under George’s direction. This is the only spoon mold that was constructed out of epoxy, and it used a clear epoxy gel coat.

General Notes

The splotches and discoloration inside the molds come from the “sand-out” phase of the mold construction. After the mold is removed from the original foam and fiberglass plug, there is a fair amount of “print through” remaining…which is surface distortion caused by the bracing material bonded to the back of the mold. That distortion was hand sanded out with a large aluminum sanding block and wet and dry paper…going from 80 grit down to 400 grit. (Total working time, 5 to 8 hours.) This sand-out process results in areas of the gel coat being sanded off, thus the discoloration.

The white areas on several of the molds are from release wax remaining after the most recent spoon was laid up.

The backing material of the molds, which obviously is to stiffen the mold, evolved from balsa blocks, to 4 x 4 lengths of redwood, to finally a piece of pipe on mold #6. The balsa blocks worked fine, but the redwood and the pipe left less “print through” which needed to be removed.