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Juliet Marine Systems: Ghost
In a press release from January 10th, 2012, Juliet Marine Systems Inc.(Porthmouth NH, USA) "announced plans to select a weapons integrator for its revolutionary new product, GHOST. GHOST is a high-speed attack craft specifically designed .... to counter threats such as piracy ...It uses supercavitation technology and high-performance jet engines to achieve hull friction reduction and high speed (60 mph)."

According to further press release the company announces the soon-to-be-designed 150-foot ship promise to evade radar. The vessel will be capable of sinking nuclear submarines and large surface vessels. Its large fuel capacity allows for long duration missions.
Sorry, no further data are available. In order to be able to calculate some assumptions have to be made. All calculation will be corrected, if new data are available.


Assumptions:

The Ghost is best described as a three hull catamaran with movable extention plates and jet engines in the outer hulls.

A maximum weight of 10 000 kg is assumed. The necessary buoyance is allocated on the central hull (20%) and extension plates with adherend outer hulls (80%).

Central hull:                              Outer hulls
Width:    5 m                              Length:                    12 m
Length: 15 m                              Max. Diameter:       0,8 m


Resistance

Resistance of the catamaran during cavitational running is composed of resistance of the outer hulls and extention plates while resistance of the central hull is neglected because it is out of water.
At maximum speed a resistance is assumed of 7000 N for each outer hull and 15,000 N for each extension plate. Since no buoyance is existend during cavitational running an additional resistance force of 5000 N is assumed for compensating weight resulting in ca. 50,000 N total resistance.


Running depth

By lowering the extension plates the running depth at maximum speed may be raised to estimated 3 m. This results in assumed large resistance of the extension plates, which obviosly are also performed to run supercavitational since openings for gas exit in the vicinity of the front region of extenion plates are visible.


Power Unit

The vessel uses jet engines as power units. Jet engines driven by gas turbines are advantegeous because of their low weight/power-ratio (ca. 0,27 kg/kW), high-performance and large exhaust gas volume, what is especially advantegeous in the time of accelleration to supercavitation movement. Taking into account the denounced velocity and the assumed resistance of 50,000 N an engine power of 1600 kW is necessary. Gas turbines in this region are industrial available and can be installed concerning weight and dimensions within the outer hulls.


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