twin fins on a fish - how far up is too far?

Hi - just shaped meself a 6 4 X 22 fishy thing… on my last attempt at such a shape I just put the standard thruster set up ( front fins @ 12" from tail) …

I removed the back fin to see what difference it made + to my joy dound the board super loose but still drivey…the board worked great.

Now then, upon reading the archives, std twin fin settings seem to be 7 - 9 inches from tail…I’ve never ridden a twin fin fin this set up but I’d imagine it to be much stiffer than the 12" up setting…

I’m considering a std set up (ie 9" up) …what differences would I see (I’d imagine greater drive but stiffer)?

Anyone else use non-std twin fin settings?

hi Silverback !

mine [on my 1970s twinny] are 10" up from the tail .

Feels a bit too slidey sometimes .

But, that could also be my light weight combined with a 3 1/8" thickness [!!] …hard to bury a rail in turns .

I REALLY like the fins though …if I ever snap it , I’ll definately mould bases for those fins / cut tabs in them !

(I’ve always wanted to have the fins further back, though… )

…LUKE , with your finboxes , how far back have / can you place your fins / keels ?

cheers !


Seems to me, fin placement is not only personal preference, but based on WPoint of the board, rocker, your surfing weight, and where you like to stand on your board.

If WPoint is well forwards, and rider is heavy for the size waves, seems a more forward fin placement, coupled with rider standing in trim position forwards, should work well.

Opposite case is small rider using WPoint back and thick board, needing to stand on the tail, needing fins to be placed well back, like the leading edge 9" example.

Don’t forget, board too loose, add bigger fins.

Board stiff, use smaller fins.

My current 7’9" twin fin, with 6x6" fins, leading edge at 14", works well up to head high, then needs better surfer.

Hi Ben

Did it thuster…will “prawnise” the board with extra fcs plugs for 8" up twin setup next week

good on ya !

it looks like a wide swallowtail thruster shape .

So you will have the 5 fin option then , later .

Did you shape any double concave into it at all …because I could send you some mini bonzer runners if you like , to play around with …

let me know if you’re interested eh ?

[they would need a 6" or so back fin , though …which I may also have …]

catchya !


22" wide ?

…if you don’t mind me asking mate …how tall and how heavy are you ?

Hey Ben, thanks for the bonzer offer but it’s a flat into V btm. I’m currently 215lbs when towelled dry…hence “silverback”… a friend thought that that’s what I looked like one day at beach when a stupid longboarder ran me over breaking a new board of mine into two pieces… it was winter and therefore a full wetsuit + hood + bad temper + overall shape I guess = …

hi jawl !

…and …

how tall ?



I just thought a silverback was one of the …er…more senior citizens with silver [read ‘white’] hair …thanks for setting the record straight there . Oh , and no offence intended , just in case you , like me , are one of the dinosaurs the aussie surf mags ignore [people over 40 , who actually surf ?? nah ! couldn’t be !! …do THEY exist !!!].