FEBRUARY 6, 2013 — The Navy's fifth Littoral Combat Ship (LCS), Milwaukee, will be the first to have new high-power density waterjets aimed at staving off rudder and propeller damage experienced on high-speed ships.
Left: Impeller of high power density waterjet
Researchers believe the smaller, more efficient waterjets will help the LCS avoid excessive maintenance costs associated with cavitation — a phenomenon that occurs when changes in pressure create air bubbles on rotating machinery, such as marine propellers.
The waterjets' new design could increase their lifespan between repairs, says ONR.
The product of an Office of Naval Research (ONR) Future Naval Capabilities (FNC) program, the waterjets arrived last month at the Marinette Marine shipyard in Wisconsin, where Milwaukee (LCS 5) is under construction.
"We believe these waterjets are the future," said Dr. Ki-Han Kim, program manager in ONR's Ship Systems and Engineering Research Division. "Anything that we can do to keep ships ready to go will ultimately benefit our warfighters."
Developed by Rolls-Royce Naval Marine in Walpole, Mass., in collaboration with ONR and Naval Surface Warfare Center, Carderock Division, the new Axial-Flow Waterjet Mk-1 can move nearly half a million gallons of seawater per minute, providing more thrust per unit than current commercial waterjets. Four of the new waterjets will propel the LCS to speeds greater than 40 knots.
The waterjets project began in 2007, and the delivery last month to the shipyard marked its successful completion.
The waterjets originally were slated for another ship program that was discontinued. Instead of canceling the waterjets program, officials regrouped and shifted their focus to designing a product that would improve the performance of LCS.
Next up for the waterjets will be full-scale sea trials on Milwaukee (LCS 5), expected to occur in the next 24 months.
Eventually, the new waterjets could be installed on 10 LCS under contract to be built by Lockheed Martin.