I would assume it’s one of mine too…never seen any others.
Where did he get that? My guess he found it at the Island facory somewhere. I remember sending some to Glyndon years ago, although it doesn’t look like he used it.
I’m guesing your chart is in inches. I remember using that size forward fin and half that as a tail fin on my in-lines. Although it looks a bit vertical, you’ll notice it has the same depth as rake, I calculated similar area to other fins I was using at the time I started playing with these.
Chuck it in a single fin box, go for a surf, and tell me how fast it goes.
Haven’t made any for a while now, still pretty busy, but hope to get onto it eventually.