US Navy developing autonomous underwater hull-cleaning robot
By Ben Coxworth
April 22, 2010
Barnacles might seem to be a traditional, almost quaint accoutrement of sea-going vessels, but they’re actually a serious problem. The buildup of marine organisms on a ship’s hull, known as biofouling, can reduce its speed by up to 10 percent. To compensate for the drag, the ship may have to use as much as 40 percent more fuel. Ships have to be lifted into drydock for the removal of barnacles, and sometimes toxic hull coatings are used to prevent them from colonizing. Hopefully, a new innovation may make both of those approaches unnecessary - it’s an autonomous hull-cleaning robot.
The Robotic Hull Bio-inspired Underwater Grooming tool, or Hull BUG, is being developed by the US Office of Naval Research (ONR) and SeaRobotics. Just a few days ago, we told you about another one of ONR’s projects, for generating electricity from mud.
The Hull BUG has four wheels, and attaches itself to the underside of ships using a negative pressure device that creates a vortex between the BUG and the hull. Much like a robotic vacuum cleaner, lawnmower or floor cleaner, the idea is that once it’s put in place, it can set about getting the job done without any outside control.
Onboard sensors allow it to steer around obstacles, and a fluorometer lets it detect biofilm, the goop in which barnacles and other greeblies settle. Once it detects biofilm, powerful brushes on its underside are activated, and the film is scrubbed off. In this way, it is intended more for the prevention of barnacles, than for their removal. Initial tests have shown it to be very effective.