What are side fins used for?
Do I need side fins?
Our Tower boards only ship with a single center fin, no matter what fin box configuration they're built with. We do this because the majority of riders will not need to purchase side fins. We install the side fin boxes to give you flexibility in how you use your board--lake, ocean, surf, river, etc. Side fins are used primarily for inceasing maneuverability when surfing or increasing tracking for heavier riders. We do also make boards that simply have traditional longboard fin setup (just the center fin) and can be used in surf but don't need side fins.
If you find your board is snaking back and forth more than you like in the water (where you're having to switch paddling sides more often than you like), you can correct this to a large degree with the fin side and configuration. The tracking can all be corrected with a change in fins, and there are really two ways to correct it. The most common is to replace the center fin with a big rudder-like fin. The second option is to add two small side fins (called side bites). On our Tower boards we use Futures Fins boxes (by design, they're a much better mounting solution on thick SUP boards) so YOU HAVE TO GET FUTURES FINS FOR ALL TOWER BOARD SIDE FINS!
Hard Board FAQs