The concave is at its deepest right between the feet to maximise lift and in so doing decrease the need for foot movement. The stinger is well forward of the old fashioned ‘flyers’ and the subsequent decrease in width below the stingers then squeezes the fins closer together so that they act as a unit. The fins are moved forward to again allow a ‘glue footed’ stance on the board.  The tail rocker curves away more than most modern shortboards whereas the entry rocker is quite moderate so that drive and planing speed is retained right between your feet. There is a slight double concave on the deck which then decreases the thickness of surfboard foam between the surfers heels and toes and the water surface below. As a result of the stinger the planshape is more parallel immediately forward which adds grip while the shortened concave adds lift. Lift without grip is skittery so this is why we have straightened the plan shape exactly in this area.