Military


Sea SLICE

SLICE is a new, patented ship technology that enables SWATH (small waterplane area twin hull) ships to operate at higher speeds while retaining their characteristic low motions in a seaway. SLICE technology's key innovation is reduction of wavemaking drag, which is accomplished by the introduction of four short struts, four teardrop-shaped submerged hulls, and speeds well beyond the 'hump' on the Froude resistance curve. Combining increased speed with stability in high seas, SLICE opens up new commercial and military markets to SWATH technology.

Lockheed Martin and the Office of Naval Research (ONR) are demonstrating the SLICE vessel, an advanced type of SWATH [Small Waterplane Area Twin Hull] configuration. The SLICE [Slice is not an acronym] prototype, introduced in 1997, has four underwater pods with propellers on the forward pods. The vessel is 104 feet long, with a 55 foot beam. Lockheed Martin designed this Advanced Technology Demonstration (ATD) vessel, built by Nichols Brothers Shipyards and Pacific Marine & Supply Company, Ltd. A cooperative agreement with ONR to validate the SLICE technology provided the impetus for this effort. The 180-ton, 105-foot prototype Slice vessel cost nearly $15 million for research and development. The SLICE ship has completed all sea tests and has met or exceeded all performance goals, including very low ship motions while achieving 30 knots in wave heights up to 12 feet.

In 1992, Pacific Marine teamed up with Lockheed Martin to research, develop, and commercialize this fast SWATH variant. Patented by Lockheed, the fast variant was dubbed Slice, because it slices through the water without making waves. The innovation lies in the arrangement of the Slice's buoyancy -- while a standard SWATH has two Coke-bottle-shaped hulls running the full length of the ship, Slice has four shorter, teardrop-shaped pods, which produce less drag. This structure allows the Slice hull to reduce wave-making resistance at high speeds by up to 35% compared to a SWATH of the same displacement. Slice's short hulls are able to push through the wave "hump" much more quickly. Slice has the same stable ride as a SWATH, but can go faster with the same horsepower.

Since SLICE is based on the principles of SWATH technology, SLICE possesses all of a SWATH's advantages: smaller size, better seakeeping and cheaper acquisition and operating costs. Adding to these benefits, SLICE has higher speed, reduced wake, better range, endurance and fuel consumption, and is built utilizing conventional shipyard practices, including design, construction, materials and equipment. Additional benefits are modular payload capability, simplified payload balancing (due to forward weight), large open deck space, unobstructed stern for loading and unloading, and propulsion amidships--which substantially reduced the chances of fouling and propeller damage. These factors combine to create an optimum small, affordable ship that operates at high speed in high seas.

One way to increase the Froude number for a hull is to rearrange displacement hulls into segments that have short lengths. SLICE employs such an arrangement. When comparing vessels of equal displacement, a SLICE vessel's hulls are one quarter the length of SWATH hulls. The correspondingly larger diameter of SLICE hulls provides the required displacement. For the same operational speed, this innovation doubles the Froude number. For example, a 500-ton SWATH operating at 25 knots would be near its wave resistance hump, while a SLICE of equal displacement would be operating well beyond its hump--taking advantage of substantially reduced wave resistance.

The ship has an advanced hullform that provides for outstanding stability and speed in high sea states and is capable of 30-plus knots in wave heights of up to 12 feet (Sea State 5). This unique hullform is a variant on SWATH (Small Water-Plane Area Twin-Hull) technology and has four separate underwater hulls that provide buoyancy, propulsion, and excellent hydrodynamic efficiencies. The ship is controlled by a patented PC-based canard and stabilizer steering and motion control system. SLICE technology is predicted to yield speeds of 45 knots in Sea State 6 (13 to 20 ft. seas); however a larger ship with greater propulsion than the existing Sea SLICE vessel is required.

When Sea SLICE arrived in San Diego in mid-June 2002, it wasn't outfitted with any systems or modules. There was a bridge forward on the craft, and the after end looked like the empty bed of a pick-up truck. Once pier-side, technicians added on a mini crane, and two modules, along with off-the-shelf combat systems and weaponry. In the space of 30 days, the SLICE was outfitted and ready to perform as a surrogate LCS in FBE-J. During the course of the experiment, Lockheed-Martin turned a berthing module into the Combat Information Center. Then they outfitted the craft with a sled to launch and tow a mine countermeasure device known as a KLIEN, and a small crane to put a Rigid Hull Inflatable Boat (RHIB) so the crew could launch another mine countermeasure and antisubmarine warfare device, a Remote Environmental Monitoring Underwater System (REMUS). Once the mission of the craft is set, the specific needs for the mission can be determined, and the craft reconfigured to best suit the mission. The benefits of a small, modular craft like this one are endless.

Fleet Battle Experiment-Juliet (FBE-J) began on 22 July 2002 and ended on August 6. During that time, the the Lockheed Martin technology demonstration vessel Sea SLICE performed as a Littoral Combat Ship (LCS) surrogate and proved to the Navy that it is capable of rapid reconfiguration for disparate missions - a key ingredient of the eventual LCS platform. Specifically, the team engaged and was tested in the following warfare areas: Anti-Surface Warfare (ASuW), Time Critical Targeting, Self Defense, Mine Warfare (MIW) and Anti-Submarine Warfare (ASW).

The first several days of the experiment focused on Sea SLICE's ability to serve as an effective data collection node in mine countermeasure warfare. Also during the early days of the experiment, the Lockheed Martin team prepared for engagements, which would soon come from small swarm boats, as well as targets of opportunity that would be identified by the Navy experiment planners. Aiding the team was COMBATSST provided by Surface Systems, Time Critical Targeting technology made possible by Undersea Systems and Management & Data Systems, the Millennium Gun from Radar Systems, and the Silent Sentry passive radar system provided by Mission Systems.

Early in the second week of the experiment, Sea SLICE participated in a mock amphibious assault executed by the Marine Corps on the beaches of Camp Pendleton. As part of what is called a "Ship-To-Objective- Maneuver," a CH-46 helicopter lifted the NetFires launcher from the stern of Sea SLICE and transported it to the beach. Once on the beach, the launcher was fired remotely from Sea SLICE by simulating the launch of a real missile through the use of a CO-2 smoke cartridge. The Millennium Gun, made possible by the partnership of NE&SS-Radar Systems, Akron and Oerlikon Contraves, demonstrated its lethality against an array of targets.

The SLICE prototype design can be used in ships as large as 7,000 tons, which would cost a few hundred million dollars with all equipment installed on board. A 2,000-ton design would be appropriate for a larger Coast Guard cutter or oceanographic vessel and would cost between $30 million and $40 million to build. Lockheed Martin is planning a conceptual design for a 400-ton to 500-ton Slice design that could be used for a smaller Coast Guard cutter or interisland ferry. SeaSlice [ONR recently changed the name] is the type of ship that the Coast Guard may consider in their Deepwater fleet modernization efforts.



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