| 摘要 |
<p>A propulsion device 100 for a watercraft that provides thrust in a first direction comprises a first wall 130 and a second wall 120, the first and second walls defining a first space and being movable relative to each other to vary the volume of the first space. The propulsion device further comprises an outlet opening 114 configured to allow liquid to be urged out of the first space along a direction opposite to the first direction and a one-way valve 140 and 150 configured to allow liquid into the first space as the volume of the first space is increased. The propulsion device is configured so that, as the volume of the first space is reduced, liquid is expelled only through the outlet opening.</p> |
