Development of a Remotely Operated Ship Hull Inspection Vehicle

The need for inspection of a ship\´s hull for maintenance, damage, or security is becoming increasingly prevalent. The jobs are presently being performed by divers or by heavy (>200 lbs) "free swimming," remotely operated vehicles. Both present methods require significant personnel and deck support equipment. This may include a series of dive teams or appropriate deck gear to lift and deploy the divers or the ROV. The flying ROVs also require skilled personnel for maintenance and handling. A simple, lightweight, easy-to-control vehicle for rapid response to ship hull inspection requirements would be an asset to the Government and commercial fleets. A full scale demonstration model of a tethered remotely operated ship hull inspection vehicle is being developed by SEACO for the Naval Ocean Systems Center. The vehicle is a nonswimming, wheeled vehicle which travels over and remains attached to the steel hull utilizing magnetic attraction forces. Design goals established that the magnetic attractive force must be sufficient to keep the vehicle attached on a moderately fouled surface (1/8" of corrosion scale or marine growth) in a 3-knot current. The vehicle is small and lightweight enough to be deployed by two people from the rail or gunwales of a ship. It is designed to travel at a maximum speed of three miles per hour and be capable of traversing over rivets and plate lap seams. The final low profile model results in a low drag configuration, approximately 16" high, 30" wide and 36" long. The outer shell is designed to accommodate a variety of teleoperator sensors. It is propelled and remains attached to the surface using magnetic roll modules as wheels. Power provided by two electric motors allows speed variation between the port and starboard sides of the vehicle for steering control. The model weighs approximately 165 lbs, including sensor. The future vehicle is designed to implement a high-pressure waterjet for surface preparation to facilitate nondestructive- testing techniques. The nondestructive testing (NDT) techniques expected to be available on the vehicle include visual systems (monoscopic or stereoscopic), ultrasonics, and magnetic particle inspection.