Replacement Knubster Fins

Gosto muito do formato da quilha, pena só ter duas cores e o logótipo não se destaca

This adds just a bit of hold by directing the water channel through the middle of wide-tailed quad boards, or quads for good hollow waves that might skip a bit on the face. They just help with holding lines or reconnecting at the end of sliding turns. They are for quads and not for trying to turn a thruster into a summer twinnie - more fin area from a little stabiliser fin is required for that.