Surfboard Tri-Fins or Thruster Fins are today’s most common set up and is found on all kinds of boards. Fast, nimble, and full of options, the tri-fin is king. You have the drive of three fins, coupled with the hold of a center fin, and the release of smaller outside fins in comparison to a big twin fin. It performs well under most ocean conditions, lending a stable feel to a maneuverable board. A thruster set-up is the go-to choice for most shapers.