Bottom crawler

A bottom crawler is an underwater exploration, research and work vehicle.¹ It is designed to sink to the bottom of a body of water, where it uses the traction of its wheels or tracks against the bottom and can move a load.¹ It can be crewed or uncrewed.¹ It can tethered to a surface ship by a cable or cables providing power, control, video, and lifting capabilities, but this is not essential.

Such devices have been proposed for use in deep sea mining.²

It was considered as a platform for nuclear missiles, but was rejected because it is restricted to essentially two dimensions, unlike a ballistic missile submarine.³

Its use is limited by the composition of the bottom; unless it is firm, the crawler can become immobilized by sinking into sediment.¹ Another serious problem is that the tracks or wheels can stir up the sediment, causing it to seriously degrade vision.¹

Its power source can be internal (batteries) or external (cable), but each presents problems.¹ Batteries are heavy and have limited capacity for sizable loads, while power cables can impede mobility.¹

In 1958, Victor Anderson began constructing the 10-ton, uncrewed Remote Underwater Manipulator (RUM) for the Scripps Institution of Oceanography which was based on a United States Marine Corps self-propelled rifle carrier.⁴ He attached a boom and claw which enabled it to manipulate objects up to 5 metres (16 ft) away.⁴ RUM was initially powered by a gasoline engine, but it was replaced by two electric motors.⁴ It is paired with the Ocean Research Buoy (ORB), a barge with a center well.⁴ RUM is lowered by crane, then a coaxial cable is attached for power and sensor signals.⁴

RUM has taken core samples at depths down to 1,900 metres (6,200 ft) and has recovered equipment from 1,260 metres (4,130 ft).⁴