Device for making adjustable underwater trenches

摘要

An underwater trenching device (10) comprising: at least one trenching tool (14); an elevation attachment point (48) configured for attachment of an elevation means for lowering the trenching device (10) to, or raising the trenching device (10) from, its operating location; at least two steerable endless track units (16) to transmit the tensile stress to move the device (10) to make trenches underwater during use; and for each steerable endless track unit (16), a first mounting arrangement (42a, 42b, 46) allowing rotation of the track unit (16) about a vertical axis, and a first actuator (44a ) configured to move the track unit (16) with respect to the vertical axis, control means configured to control the action of the actuator (44a), the device further comprising a main body portion (12) to which the portion is attached (48) of elevation fixing and in which the endless track units (16) are mounted, characterized in that each adjustable endless track unit (16) is independently adjustable, and in which each unit (16) endless track is attached to a first end of a respective leg (26), the second end of leg (26) being fixed to the main body portion (12), the track units (16) being rotatable with respect to to the respective legs (26) with respect to an axis (28) nominally horizontal and the respective second ends of the legs (26) are fixed to the main body portion (12) and can rotate with respect to the main body portion (12) with respect to a nominally horizontal axis (30) extending substantially perpendicular to the direction of travel of the device (10).