We often get questions about where to place the fins on a surfboard. In order to provide some guidelines we have developed the attached chart:
This chart shows general placements for longboards with 2+1 setups, thruster or tri-fin setups, and quad fin setups.
Keep in mind that these are general guidelines, to be used as a starting point and work well with "normal" dimensions. For example the quad setup here works well with your typical board, but for a mini simmons I would bring that fin cluster back further on the board closer to the tail.
Generally speaking the closer the fins are together the looser the board will feel, the further apart they are (from nose to tail) the stiffer the board will be and the more drive you can put into it.