| 摘要 |
<p>An submersible boom which pivots about an extremity which is fixed to a surface vessel used to excavate a trench on the sea bed, its other extremity being attached to a cable from a winch on board the vessel. The length of the boom exceeds the depth of the sea in the locality of the trench, the boom being lowered and pivoted to effect the excavation. During transit, the boom is raised to the horizontal above the water line, excavating machinery being mounted on the submersible extremity. The effective length of the boom may be varied with changes in depth to maintain the machinery vertically below a diving tower.</p> |
