Patent ID: 6053663
Filing Date: 2000-04-25
Classification: E02F

Abstract:
Underwater excavating apparatus (319, 329) for creating a local water flow or water jet in a body of water, in such a way that bed material from the bed (321) below said body of water can be displaced, which device comprises a jet pipe (301), a first screw (302) disposed rotatably in the jet pipe, a cable, and a second screw (303) accommodated in the same jet pipe (301) and arranged coaxially with respect to the first screw (302), wherein the second screw is rotatable in a direction opposite a direction of rotation of the first screw (302), the opposing rotational direction, pitch, and speed of rotation of the second screw being such that an amount of torque generated by the second screw is virtually the same as that of the first screw (302).