High Nose Rocker Prevents Pearling, but; Exposes the Underside to a Dangerous High Speed Collision
High rocker prevents a pearl dive, but; the bow becomes vulnerable to high impact. In an air drop, the bow acts as a landing pad due to angle of attack and gravitational pull. The surfboard bow impacts the wave at high speed and launches Torrey Meister. The catapult is identical to a pearl dive, but; Torrey's board does not dive under water.
Hydrodynamic lift supports a surfer when he moves fast. Speed and a flat bottom surface produces lift. At high speed, water cannot be displaced by fast moving flat objects. Water cannot move out of way fast enough. This is the reason surfboards plane. This is also what causes a surfboard to stop in both a pearl dive and high bow impact. Increasing rocker may keep the tip above water, but; not the bow. When the bow impacts water with speed, water acts like hard solid ground because it cannot move. A flat bow must remain above water at high speed and avoid high impact. A flat bow will generate resistance, especially if the nose rocker bend is extreme. Increasing nose rocker too much, increases risk of catapulting a surfer.
In the underwater photo below, the surfboard is distorted due to light refraction. The bow is pushing water and providing lift and support to the nose. Water spills above the board in an eddy and does not add much to downward forces. Downward force comes from the surfers weight.
At lower speed a flat bow can push water aside. Rocker bend at high speed, at the perfect angle, will produce lift on the upward bend of nose rocker bottom. The bottom shape is doing what it is designed to do, generate lift. The lift counters the forward thrust of the board and may push the board back. Water accumulates ahead of a bent flat bow in the form of a bow wave and blocks movement. Spray flies but, not enough moves out of the way in time. A skilled rider cannot keep his footing at high speed, with sudden deceleration. A rounded or vee bow(nose underside) will absorb impact and push water aside. The bow wave moves out of the rider's path. The surfer may ride further and possibly recover.
Surfing has evolved with flight, a hard landing can launch a rider off his board. Surfboards can land without abruptly catapulting a rider, by using shapes from the past. A round or vee bow cushions a landing and keeps the board moving through high impact.