Searched the archives on this but wasnt really alble to narrow it well. Ive been reading alot about fin design. I find it pretty amazing actually all the info and theories about fins and all the design factors like foil, rake, toe, cant, etc. What Im curious about now is the logic and physics of the actual placement of the fins. I know theres alot of determining factors like rails and tail and all, but how does the fin placement alone affect the board? What are the theories behind this? What are the differences in how you would approach a single, and more particularly twins and thrusters where the fins have to be in tune with each other?
Theres a lot of hype when it comes to fins. Fins are basically a control element.
Without fins the board would slide all over the place and be unridable.
Simon Anderson wanted a fin configuration that turned like a twin fin but was more stable (minimize/eliminate sliding) and the Thruster was born. Thrusters gives you the added benefit of drive or forward projection using improved lateral leverage.
Toe in: offers a rudder like effect for efficient turning and gives added drag for lift
Cant: Offers lift to the tail to catch waves earlier and help generate speed.
Youll can learn a lot by experimenting…on a small day, go surf your favorite thruster without the front fins…then with front and without the center fin…etc etc
the real beauty of the Thruster is the number of benefits is a relatively simple 3 fin configuration…leverage, drive, turnability, lift. Basically lots of performance and control. Probably the greatest technical/design achievement of the modern surfboard.
Too bad a lot of people don’t realize the bonzer fin setup is even better than the thruster. With a bonzer (especially 5 fin) you don’t have to constantly pump to get speed (like a thruster).