Outboard tunnel boats are the fastest-turning race vehicles on earth. The sharp, 90-degree transfer where the tunnel sides meet the bottom of the sponsons helps the boat settle in the water as it enters a turn.
The submerged sponsons make the boat turn as if it were on rails. It is common for drivers to experience 4.5 to 5Gs as they enter a turn at 120 mph and come out at 90+ mph. Obviously, only experienced racers should consider this type of hull.