When drawing full-sized templates on my sidewalk and patio to sort out a shape before taking tools to foam, I thought that some of the templates might work going backwards if made wider. I started with a 6’ 10” x 18 1/2” rounded pin tail template, added 3" and two 1/8" stringers to the middle to yield a 21 3/4” wide board. I cut 13” off the nose of a 7’ 11” semi-gun rocker and carved it up. Fins were placed by percentage of board length from the tail to the fin’s center of pressure. Toe-in was determined by calculating the zero-lift angle-of-attack for the side fins selected and aligning that straight ahead. All very standard fare. The side fins are standard sized, and the center fin was sized between same-sized thrusters and a 2+1 larger back fin setup.
The first wave I caught was a shoulder to head high wave at The Slot at Steamer Lane. With all that surface area, catching the wave was super easy, then I tried a turn… Wazeeeeeee!!! SUPER LOOSE, TOTALLY NO CONTROL! Oops, too much curve in the tail! The board was fast though, and I easily flew through sections - not by trimming a line, but by sliding in a general direction with only slight control over where I was going. I tried the board at Ventura County points with pretty much the same result.
I tried adding Gurney Flaps to the inside of the trailing edge of the fins, to change the incidence, and this helped somewhat on waves at Indicators at Steamers. Of course, immediately downstream of the Gurney Flap the flow cavitated, so the fins buzzed. Next I epoxied thin pieces of G10 sheet glass in front of the Gurney Flaps to create little ramps, and then filled and faired with epoxy filler to make a nice curve. On the other side of the fin, I sanded it down to meet the new inside curve. Now the fins were effectively toed outward - and I do know that in juicy conditions this will lock the board up. I took the board out on a small day at Rincon, and it was able to trim a decent line.
Somewhere in all this, I learned that the foam and/or epoxy was reacting to the paint of my skull and crossbones graphic and causing bubbles in the bottom nose area of the glass job, so all that had to be ripped out and patched up.
I thought I’d try it as a single fin, so I ripped the thrusters out, and patched the board up. Then I decided to give up, and do a reshape. That is what is pictured here, but the original tail template line is shown by a blackened piece of thin masking tape. It’ll soon receive a single fin.
Hyper loose boards with lots of planing area for mush-burger waves are a viable design, but this one, in its original configuration, over did it.
This board spawned two others: a 6’ 10” x 21 3/8” single fin with a template that is svelte compared to this one, that is a remarkable ride; and something that is best described as a 9’ 4” x 23” traditional longboard template with 2’ 6” cut out of the middle and adjusted to work as a 6’ 10” x 22” with a 2+1 fin setup. That one I haven’t gotten into the appropriate mush-burger waves yet, but it is similar to boards I’ve seen by other shapers.