Viktor Schauberger was an Austrian forest caretaker, naturalist, parascientist, philosopher, inventor and biomimicry experimenter.
Schauberger developed his own ideas based on what he observed in nature. In Implosion magazine, a magazine released by Schauberger's family, he said that aeronautical and marine engineers had incorrectly designed the propeller. He stated:
As best demonstrated by Nature in the case of the aerofoil maple-seed, today’s propeller is a pressure-screw and therefore a braking screw, whose purpose is to allow the heavy maple-seed to fall parachute-like slowly towards the ground and to be carried away sideways by the wind in the process. No bird has such a whirling thing on its head, nor a fish on its tail. Only man made use of this natural brake-screw for forward propulsion. As the propeller rotates, so does the resistance rise by the square of the rotational velocity. This is also a sign that this supposed propulsive device is unnaturally constructed and therefore out of place. Wikipedia