The drag from barnacles and slime on the hull of a ship can cut vessel speed by 10%, which can lead to 40% more fuel consumed to counter the drag. This translates to $500 million annually in extra fuel and maintenance for the U.S. Navy. And a dirty hull can also make a ship ride rougher in the water. To counter this problem, engineers at the Office of Naval Research have developed the Hull Bio-mimetic Underwater Grooming robot, or Hull BUG.
The robot uses vacuum or negative pressure to attach itself to the hull and four wheels to move around on it. Onboard sensors detect crustaceans and films that need to be removed, as well as obstacles such as a sharp keel or sensitive sensor pods that the BUG must avoid. This lets the robot’s computer plan a path around the hull. ONR says the battery-powered robot should be autonomous and not require a tether. As it moves over the hull, the robot could use rotary brushes or water jets to clean the hull. Both tools are among those being tested, and a full-ship demonstration is expected in 2015.
If the BUG is a success, it could save money in fuel for both Navy and commercial ships, extend the time between dry-dock repairs, and pave the way for using new nontoxic high-tech coatings.