| 摘要 |
When swimming, man gets propulsive force from pushing water backward by hands or feet. However due to the limitation of the size of his hands or feet the propulsive power he can get from naked hands and feet in the water would be not sufficient, and accordingly the swimming speed is low. In order to overcome the above limitation, he could put a flat board on each foot and push the boards backward with his feet and legs, and he can push the water backward more, gets more propulsion and consequently the higher swimming speed. In comparison that the conventional equipment, so-called 'fin', does get propulsion power by swinging the feet and legs up and down, this invention obtains the propulsion power through the reaction power of the water pushed backward by pushing the board backward straightly with foot and leg.
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