Distance from tail for glassed on single fin

I was looking for recommendations on how far I should glass a 9.5 inch fin from the tail on my 9’3 “noserider”. I normally surf a 9’8 log with a big fat hatchety fin on it about 4-5 inches from the tail, and I was looking for this to be a shorter faster version of it. Everything varies, but I was just looking to see what other thought. Fin is similar to the one in pic.

Only you would know what works for your style, your boards, etc., but just to offer a contrasting opinion, I ride a 9’6" with a 10" flex-style fin with trailing edge placed 8-1/4" from the tail. I tried about 4-5 different fins before settling on the present one. I like to dial in the fin/board combo and wouldn’t glass-on for that reason.

I agree, depends on surfing style. Do you want to hinge your turns from the tail, or do you want more of a carving turn on rail?

I wanna surf it from the tail like my 9’8 but wasn’t sure if 4 inches from the tail would be do drastic on a 9’3. I figured since it was a shorter board I wouldn’t push it as far back. I guess I’ll just slap it at 5 inch from tail

The are many variables in this picture, tail width, rocker, I used 7-8" as a starting place on narrower, flatter rockered boards, Joel Tudor says no more than 4" for a classic LB. On fin box boards, I put it where I think it will work well and then play with it, my “kit” with a laundry marker and screw driver, 1/4" increments up and back until you find the sweet spot that feels best

9’3
19" from nose @ 12
23" wide
3" thick
15 1/2" from tail @ 12
Tail rocker 4 1/4

5" sounds perfect. I used to go with a bigger fin than I thought might be needed and if it felt too stiff, I’d grind it down a bit. I’ve also built up extra width by adding glass layers to each side and smoothing it all out but it’s easier to get it right the first time. Ordinarily I’d say go farther forward but with TR of 4 1/4", 5" from tail should work. Worst case? Grind it off and do it again in a different spot. Or add a box.

Thanks john, well 5" it is hopefully it gets to stay there. I’ll go with what you said and pop a 10" fin in too and grind down if needed. My main reason was to avoid waiting for the cure time of a fin box. I can UV cure a glass on and be in the water that day.

I read some of what youre talking about, in regards to thickening your fins, in the fin theory discussion. How plump are you making those fins?

…hello, my approach is different; couple of days ago I delivered an all around performance 9 2 in 2+1 box set up. The main fin is only 8 inches and I set it at 8 inches. Was not a custom order but the guy that bought it is around 70 kgs.
Light surfer + tail area the same as a shortboard + boxy rails + not so much tail rocker.
But you have lot of curve in that tail so yes, better to have a fin with plenty of base or more rake or more tip area and to move the fin back.