Do you use a mould ?
And has this fin a pvc core or is it solid?

I notice you’ve possibly got the tooless part at the wrong end. Pin typically goes at the front so the tooless part has less pressure..

Love what you are doing. Follow you on facebook.

Made some mnore fins and did some branding. Gong for a thinner model too similar to FCS Skindog 7" which is probably the best fin I ever used for wve sailing. Been trying my own in Sweden during the Wave Classic 2026 but blew out my knee (mensik) and finished last. Rydberg, Viscowitch, Living on top. Stabilt grabbarna!
1/4 weight of G10. 1/2 the weight of carbon fins from MFC. I just can't get my head around it. I have to say it seems stupid to say that everything works best-ever just as we make it, so I'll just shut up. Can't sail and proove anything anyway.