Movable cable plow for constructing underwater cable

Claim 1

Apparatus for dredging a groove in a sea bed for depositing an underwater cable in the groove, said apparatus comprising: a main body towable horizontally along a surface of the sea bed, a plow for dredging the groove in the sea bed, attachment means for attaching said plow to said main body such that said plow extends vertically with respect thereto, said attachment means comprising at least one Y-shaped arm, means for pivoting the non-forked end of said at least one arm to said main body for pivoting in the plane of the arm about a horizontal axis, so as to provide a vertically upper and lower fork for said arm at the rear end of said main body, means for pin connecting the lower fork to said plow intermediate of its ends, for pivoting said plow about a horizontal axis relative to said at least one arm, a first hydraulic cylinder pin connected at one end to said upper fork of said at least one arm and pin connected at the other end to said plow above the pin connection between said plow and said lower fork, and a second hydraulic cylinder secured at one end to said main body and at the other end to said at least one arm rearwardly of the pin connection of said at least one arm to said main body such that operation of said first hydraulic cylinder causes said plow to pivot relative to said at least one arm to vary the angle of attack of said plow with respect to said sea bed and operation of said second hydraulic cylinder causes said arm to pivot about its pin connection to pivot relative to said main body, whereby, said plow may be lifted vertically without change in orientation with respect to said sea bed during operation, and a planar cable guide member and torsion bar hinge means for mounting said planar guide member to the rear of said plow such that said guide member extends vertically and constitutes an extension of said plow and pivots about a vertical axis under the restraint of said torsion bar, whereby, when the direction in which the plow is towed is changed to avoid an obstacle or hard ground, only the plow is required to travel in the new direction with the cable guide member pivoting laterally with respect to the plow under the torsion bar restraint to minimize transmission of lateral forces to the main body to ease the change in direction of the plow and to minimize the danger of the plow tipping.