I ride a 9’0 17x22x13.75 longboard with 2 /1 set up . I am wondering about what is a good placement for my center fin. I live on the East coast and ride mostly small beach breaks . I have rode it all the way up before will that help or hurt the performance of the board.
I put mine just behind the side fins,and then forget about it,unless I ride over someone!
The 2+1 fin set up is one of my favorites. I usually carry two center fins... one at about 5" and one at 7" or 8". That covers a huge range of riding conditions. Play around with the positioning of each. Some guys file or mark a scale on the box so it is easier to keep track of where the fins are positioned. One of those 'finger tighten' fin bolts is good for in the water adjustments.
I have a board of similar dimensions. There’s a PIC of it on this page of this thread (4th post down):
I’ve used it configured that way on fairly-to-very hollow waves from 5’ up to about 12’. Works great for me in those conditions. But I prefer longer boards with more volume (either a squaretail single or a rounded-pin 2+1) for small, low-power beach break.
The general rule of thumb is to align the leading edge of the center fin with the trailing tips of the side fins. From there you can adjust it on 1/4" increments. Forward should be looser for small days, and further back will stiffen it up for when the surf gets more powerful.
[img_assist|nid=1054634|title=2+1 placement|desc=|link=none|align=left|width=220|height=166]
in the above pic is how I used to have my center fin(front edge lined up or just behind with trailing edge of side fins,as is commonly stated correct to have a responsive feel) until quite recently,when I got my hands on a speed shape 9.0 that seemed a little stiff on the cutback.moving the center fin quite a ways back,like on a thruster shortboard,loosened the board right up.Since,I have adjusted the other longboards with 2+1 accordingly,and they are even better.Who says you can’t teach an old dog new tricks.Hope it helps someone.