The Theory of Balance This is a paper on two of the basic balances that effect the way surfboards ride. These balances pertain to all boards regardless of shape, size or style of surfboard. The original theory came about 20 years ago when comparing twin fins to single fins. The basis of this theory is that most of the performance aspects of any board are effected by the balance of pitch and resistance between the nose and tail of the board. Imbalance’s hurt the performance of the board. These balances are effected by: a. the board shape b. fin size, shape and placement c. rider size, style, stance and ability d. wave size, shape and speed Small changes in any aspect of the board design can make a great deal of difference in these balances and therefore the ride of the board, positive or negative. Once one understands balance it is easy to tell what is wrong with a board just by watching it while being surfed. It is then just as easy to correct the balance by adjusting fin sizes and/or shapes. In the 70’s the single fin box gave us control of pitch. A large back fin would (in effect) pull the tail of the board down, keeping the front edges free especially in large or hollow surf. In smaller waves we would use a smaller fin to reduce drag and increase speed as the tail of the board was allowed to ride higher. Resistance had to all be built into the rails and outline curves of the board. The magic board was pretty rare. In the late 70’s and early 80’s the twin fin boxes of the day allowed us to change resistance. A larger side fin would resist the wave and transfer the balance of the board when “on rail”, forward. This would cause more rail length and less bottom surface to be engaged during a turn. A smaller side fin would allow less rail length to be engaged and more bottom surface, as the balance of resistance shifted aft. But with no control of the balance of pitch the magic board was still very rare. We did find out at that time that we could control pitch to some extent by softening or hardening the edges in the tail of the board. Of course, deep vee was very popular in these boards. That was also a way of lowering the finless tail of the board into the water. This couldn’t be changed after the board was finished though. In the remainder of the 80’s and all of the 90’s the 3 fin has dominated without an interchangeable fin system. Most of the boards from this era have less than optimum fin set ups, but in many ways the 3 fin is a bit more fool proof. By optimum I mean the board develops excellent drive, glide and speed without hang ups. Generally, for most surfers, the three fin boards of this era were over finned (to much fin). This creates a board that will work in a wide variety of conditions but, because of excessive drag, is rarely optimum. The change to thrusters with fin boxes has, for the first time, given us control of both pitch and resistance. What this should mean is the highest percentage of excellent riding boards ever but this is all dependent on the understanding of the balances of pitch and resistance. The quest for one perfect board has been an incredible drain of time and energy within the sport. It has also narrowed our perspective, keeping us away from potentially revolutionary advancements. When I first discovered the theory, the simplicity of it took me by surprise. To find out that as a surfboard designer the best that I or anyone else could ever achieve in this custom shaping world was a good guess was hard to accept. In fact, all this paper discusses is pitch and resistance. It doesn’t discuss total lift, total resistance, weight, balance of weight, flotation, balance of flotation or any of a million other variables that the interrelationship these and other design aspects contribute to. Consider for a minute that the rocker, outline, rail thickness, rail contour, edges, bottom and deck contours and a myriad of other subtleties all have an effect on overall pitch and resistance balance. Any change in one effects the others. It is easy to see that striking a perfect balance in every board would be quite impossible. Even machine shaped boards have variables that can’t be controlled. If you add to this the fact that there are different balance considerations in different surf conditions, then consistent perfect balance becomes even more improbable. Finally add different surfers of different ability, style, stance, weight, height and another myriad of variables and consistent balance becomes totally impossible. For me personally the theory did free my mind from many things that confused me before and allowed me to concentrate on things that I felt WOULD make a difference. Things like a lighter weight surfboard technology, a usable volume rating system for shapers, an effective scaling system for different size and ability surfers, and a more ecologically responsible board building system. It also made my personal boards a lot more fun. With the existence of surfboard balance proven, any question of the existence of a single perfect surfboard shape can now be put to rest. In short it doesn’t exist. It can’t. The real beauty here is that we can get close and balance can be had in todays board with a few sets of fins and a knowledge of balance.