I’ve been screwing around with single fin stubbies for a while now. I mostly surf them in slower conditions when I just want to go with the flow. The one below is a reshape off a prior egg I surfed into the ground. It’s a PU blank with veneers and Vinylester lamination. I’ve been surfing it with a wide based Greenough style fin that has a bit less rake. I previously surfed it with a Starfin and liked the pivot but didn’t like the lack of drive. I’m interested in the elliptical fins so I thought I’d try one with some rake and more base, and am hopeful a couple of you guys will chime in and help me with my learning curve.
For info, I’ve been using a McCoy-style layout for my stubbies, with the wide point back and that rolled vee with the sharp release in the rails (works great, BTW). The one in the pic below is 6’0" x 20.5" x 2.5", the tail being a little wider (17.5" than the nose (17"), and a flat rocker. As you would expect I surf it more off the tail and don’t move around a lot on the board.
I used a freebie sketching program to dummy up some fin templates in order to (approximately) calculate surface areas on these various shapes. Obviously the curves aren’t good enough to use as a template but for design purposes it’s pretty easy. The 4 figures in my pdf below show an approximation of the fin I’ve been surfing (#A) and roughs of 3 other layouts. #B looks to have too much curve and way too much area, #C started off with too narrow a tip for my eye so I moved the leading edge out (that widened the base). #D looks a little better to me overall. Right now I’m gravitating between #C and #D but I’m concerned about adding too much surface area. I want lots of drive but I also want to get a smooth and reasonably nimble ride.
Hence my questions: By adding more surface area in the middle of the fin where (some say) there’s less turbulence and retaining some rake to get a little more carve and a little less pivot, how narrow can I go with the base? Should I be shooting for a narrow tip on this or retain more surface area all the way through?
I did this board as a test mule for a couple things. I cut the bottom fin patch so I could eventually add a fin system, which I’m probably going to do this summer. I think this board will work with a quad and possibly as a 2+1, so I’m interested in suggestions for that, too.