  We derive the equations of motion for the planar somersault, which consist of
two additive terms. The first is the dynamic phase that is proportional to the
angular momentum, and the second is the geometric phase that is independent of
angular momentum and depends solely on the details of the shape change. Next,
we import digitised footage of an elite athlete performing 3.5 forward
somersaults off the 3m springboard, and use the data to validate our model. We
show that reversing and reordering certain sections of the digitised dive can
maximise the geometric phase without affecting the dynamic phase, thereby
increasing the overall rotation achieved. Finally, we propose a theoretical
planar somersault consisting of four shape changing states, where the
optimisation lies in finding the shape change strategy that maximises the
overall rotation of the dive. This is achieved by balancing the rotational
contributions from the dynamic and geometric phases, in which we show the
geometric phase plays a small but important role in the optimisation process.
