templating fins

back to basics !

I just realised I had never posted on this ?!

hope it’s not too basic [or boring?] but I thought maybe someone may like to know

Basically , I start of hand drawing the curves .

Or if I see an existing fin I like / have , I will modify it [see other thread , ‘modified fins’] …by tilting it forwards or backwards , shortening it , narrowing it , widening , lengthening it .

here’s a few …



I do all mine on 1 inch grid paper…

It makes checking the leading edge rake, and chord length as a function of depth, pretty easy.

Those two things form the basis of how I understand template to interact with surfing performance, both can be quantified mathematically and compared fin-to-fin.


Great stuff and never too basic as there are constantly new people who get their eyes open to the world of Sways!

Would you happen to have a singlefin template? Or some good measures? It’s going on a 6’4-22-2 3/8

I’m thinking something quite felxible and glass on



hi ben

i got your letter thanks

still havent foiled those canards yet

but i did order some diamond cutting blades for my scroll saw

that way i can cut the tabs really accurate

i was hoping u might have a proven keel oultine for a 5 10 fish

ill make them up if i like the look

look forward to your relply

This one goes great as a rail fin. Maximal drive, not so much hold, made for smaller days when you REALLY want to generate speed and don’t need the hold (and aren’t scared about poking your eye out). The progression of chord lengths vs depth is a true elliptical, the leading edge rake is identical to the most common thruster fins, and the overall area is average with respect to common thruster fins. If you want more hold take some chord lengths from the base and move them to the tip.

The “Orca” fin I used for the singles. Modified cutaway to prevent a sorta washout feeling on harder turns, max chord length about 2 inches up, and the fin is otherwise an ellipse (which is different from having an elliptical progression in chord lengths). Works great in a single, this is the 7.5" version for a 6’6" with a 13.5" tail, but it scales well to a 9 incher for bigger boards (it doesn’t really scale in all dimensions equally, more lengthwise, less chord-wise, keep same rake angle).

i was thinking twin fin though

is that top one for a quad or twin

Its a thruster rail fin.

Too small for a twinnie.

Looks a little like the H2… but with a thinner tip.

How close is it?

Looks a little like the H2... but with a thinner tip.

How close is it?

I made it before the H2 existed.

You can probably photoshop them together to check how close, I’ve never taken a close look at the H2. I don’t run it at an unusual cant though. Just that template, foiled WP 20%, rounded front edge, canted normal. Compare the leading edge rake (the bottom 2/3rds) with Al Merrick’s template (which was not my model - most fins are VERY close in leading edge rake).

hey thanks dave [‘blakestah’] for replying to this thread

and paul [‘silly’] ,

i have a few more hemp fins in the works for your quad fish …

…or maybe , some carbon fibre thruster side templates ? …

i could mail you some paper copies of some of my templates , if ya like , or else … please feel free to check out my ‘keel templates’ or ‘twin fin templates’ threads [now you can see the piccies , that should be helpful !]

hi moKSa !

there is also a ‘single fin templates’ thread of mine here at sways too, by the way

thanks to all who contributed …

please feel free to share your templates here anyone ! [thanks for sharing yours , blakestah !]



p.s. -

Paul , here’s the checkered fin option …

rooster said he was gunna post a few different templates for me

im after keels

as its a fairly oldschool shape

my last one the keels really hummed when i turned for some reason

anyone know why?

fin hum is a frequently a result of fin vibration usually caused by cavitation. poor hydrodynamic foils can cause this. make sure your trailing edges are fairly sharp and that the fins are not loose. could be lots of things. post pics.