I’m working on 9mm ply quad fins. The tips are at least twice as thick as fiberglass fins. They will be used on a 6’2 fish type for small/medium beachbreak. The picture below is front and trailer. The bottom third is only used for clamping and will be cut off.
There is no maximum fin tip thickness.
A thicker tip will have two effects:
Your fin will be stiffer -> less forgiving but more responsive
Your fin will stall at a larger AOA but will stall more severe. (read: more resistance to spin out but the spin out will be more severe, but since you probably fall at a spin out, the severity is not an issue)
I hope this helps.
Your foil looks good by the way.
Thick tips, more vortex, more drag, feels slower and sluggish.
Thin tips, very streamlined, fast, quick, but sensitive to foot pressure and sudden changes of direction.
Correct tip thickness covers both bases OK.
Now cord is another foible, similar in many sways..
They are glassed but redoing them can’t hurt. I’ve already put quite a lot of effort getting them like this. I’m not sure what kind off wood this is but the quallity seems really good- no grow rings and really hard to foil. I’ve compared these fins with other keels I’ve foiled. Those are so much more flexible in the tips, cheap wood, but I love the board and the way the fins feel. Also more delicate. 9mm ply seems a bit too much for thruster/quad type fins. The foil seems right top to bottom, no flat spot at the base. With the tips thinned they might look all weird. I gonna give it a shot
Thanks