New High-power Waterjet Propulsors for Navy LCS

The Navy's fifth littoral combat ship (LCS), 'Milwaukee', the first to benefit from high-power density waterjets.

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.


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.



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. Repeated occurrences can cause whole chunks of metal to wear away, leading to frequent repairs and replacements.


"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."



Chief of Naval Operations Adm. Jonathan Greenert's 2013-2017 Navigation Plan calls for fielding improved ships to support counterterrorism and irregular warfare missions at sea and ashore. The LCS will play a big role in the Navy's plan as a modular, adaptable vessel for use against diesel submarines, littoral mines and attacks by small surface craft.


Next up for the waterjets will be full-scale sea trials on Milwaukee (LCS 5), expected to occur in the next 24 months.