Meet the 'Ghost': The Boat that Sails Through Bubbles

The Ghost uses supercavitation and SWATH to slice through the waves.
Christopher McFadden

The "Ghost" might be the most exciting, and impressive, innovation in marine technology since the submarine. Fast, agile, and mean-looking, could this diminutive little vessel be the answer to blue-water fleet protection and SPECOPS?

That is, of course, if the US Navy actually buys it...

What is the "Ghost" stealth boat?

The "Ghost", or the Juliet Marine Systems "Ghost", is a highly advanced reconfigurable SWATH stealth-capable warship currently under development for the U.S. Navy. The vessel's design enables it to travel over water at a fraction of the friction experienced by conventional vessels.

This provides it with impressive maneuverability and speed on the water. Capabilities that would prove essential to countering small, highspeed vessels like motorboats. 

The vessel is also said to have a very small radar signature owing to its incorporation of advanced technologies and physical form. 

According to Juliet Marine Systems, the "Ghost" can be used for a variety of missions including force protection, special operations, and intelligence, surveillance, and reconnaissance roles. It could also be used for civilian duties, including, but not limited to, high-speed maritime ferry or taxi services, offshore oil rig supply, or even as a pleasure craft. 

The inspiration for the "Ghost" came from a perceived need to provide a means of protecting U.S. Navy warships and personnel in both deep and shallow waters following the bombing attack on the guided-missile destroyer U.S.S. Cole in 2000. The Cole was refueling at Yemen's Aden harbor at the time. 

The Ghost USS Cole
The "Ghost" was developed in response to a small, high-speed motorboat attack on the USS Cole in 2000. The attack caused severe damage to the warships hull. Source: FBI

During the attack, a small motorboat, packed with $500 of explosives was able to penetrate the U.S.S. Cole's defenses and detonate midships.

This caused a gaping 12.2 m (40-foot) wide hole in the USS Cole's hull, killing 17 sailors and injuring many more. After an FBI investigation, the attack was discovered to have been organized and carried out by terrorists from the Al-Qaeda terrorist network. 

The "Ghost's" hull is 18.9 m (62-feet) long, and of an angled, faceted design that has more in common with stealth-capable aircraft than waterborne vessels. Empty, she weighs in at 6.4 tonnes and has a range of between 563-805 km (350-500 miles). 

Her design also makes minimal use of windows, to further reduce the radar signature. 

It has an overall stout shape (when viewed in profile), and the forward sections are well-slanted. The bridge of the "Ghost" has a 5 cm (2-inch) thick ballistic windscreen behind which her two crew (a pilot and co-pilot) operate the craft. 

thie ghost stealth ship
The "Ghost" in all her glory. Source: Juliet Marine Systems

The "Ghost's" most standout feature is its dual-strut supercavitating pontoons (nacelles) that are known, technically, as a small waterplane-area twin-hull (SWATH for short). Control at high speed is achieved by using a series of gyro-stabilization and over 20 underwater control surfaces to maximize the craft's agility.

This is all computer-controlled in much the same way that electronic control systems are used to prevent cars from slipping on the road at high speed. This enables microsecond calculations and corrections to be made without the need for human input.  

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The vessel is also capable of operating in wave heights of up to 2.4 m (8 foot)

When traveling at less than 8 knots, the ship sits in the water up to its centerline, with its two 3.7 m (12 foot) struts submerged, parallel to the water's surface. As the craft accelerates above 8 knots, the hull can be lifted out of the water by bringing the two struts closer together. 

This, along with its supercavitation technology (more on that later), enables the "Ghost" to skim over the water's surface. Her hull is constructed using aluminum and stainless steel, making her particularly lightweight and corrosion-resistant. 

The angular shape of the hull is inspired, in part, by stealth capable aircraft like the veteran Lockheed F-117A Nighthawk stealth fighter. This makes the vessel virtually invisible to radar detection. 

A central cargo hold can be used to carry either cargo, weapons, or passengers which can be loaded and unloaded using a single hull door. 

Propulsion is provided using a pair of 1,342 kW (1,800 horsepower) gas-powered turboshaft engines incorporated at the end of each of the boat's struts. Future models may replace these engines with a pair of General Electric T700 turboshaft engines.

The Ghost at sea
Source: Juliet Marine Systems

The location of the boat's engines, fuel, and most of its computer systems in its nacelles also offer the vessel some added protection, as they are mostly protected by the water around them. 

The boat is expected to take on some similar duties to attack helicopters, by intercepting illegal shipments and incoming small attack vessels, once equipped with the right weapons and other technologies required for such roles.

For example, it is envisaged that she could be equipped with 20 mm cannons for anti-surface warfare, or rockets (like the BGM-176B Griffin missiles, or Advanced Precision Kill Weapon System rockets). Rocket exhausts could be vented into the water column through the struts, dramatically reducing the vessel's heat signature in combat, too. 

The vessel could also be equipped with a variety of electro-optical sensors, radar, sonobuoy launch tubes, sonar, and fore/aft torpedo tubes. It could also, conceivably, be equipped with a towing boom for mine-hunting sonars using systems like the Raytheon AN./ADQ-20A.

How does the "Ghost" overcome wave impact and water drag? 

Traditional high-speed boats, like speedboats, that travel fast over the water, often suffer from wave impact or wave hopping. This not only reduces the efficiency of the boat on the water surface but also produces a very uncomfortable, if exhilarating, ride for any passengers on board. 

Wave impacts are the easiest to overcome, thanks to the use of the previously mentioned SWATH technology. Because the main propulsion elements of the boat are submerged, the only parts of the vessel exposed to waves are its struts. 

The leading edges of these are very thin, and sharp, meaning wave impact is minimal. This helps make the "Ghost" a very stable vessel at sea. 

Water drag, however, is another story. 

The "Ghost" overcomes this, in part, by using counter-rotating propeller units that pull and stabilize the front sections of the engine nacelles on the leading edges of its nacelles. This setup helps the "Ghost" take advantage of something called supercavitation. 

The Ghost propulsion system
Two main technological innovations help make the "Ghost" an impressive vessel by any standards, SWATH, and its drag reduction technology. Source: Juliet Marine Systems

This uses the propellers to form a tunnel, or cylinder, of fast-moving air bubbles behind the propellers, and around the Ghosts' nacelles. In other words, Ghost could be described as traveling through a low-pressure tunnel of foam, rather than denser water, making it very fast indeed. 

This process is accelerated by funneling air down the struts to ultimately form a "bubble" of air inside the water large enough to enshroud the craft's nacelle units. Not only that, but this bubble curtain can be actively managed without the need for specialist equipment like pumps. 

You can liken this, in part, to the turbochargers on car engines. These use exhaust gases to help improve the performance of the engine as a whole. While not exactly comparable, the principle of using otherwise wasted energy to boost performance is a great innovation. 

This enables the "Ghost" to travel at very high speed, for a boat and greatly reduces the issues caused by drag from the water.

To date, the "Ghost" has managed to clock up speeds of over 55.5 kph (30 knots), but Juliet Marine Sytems are confident that the vessel should be able to top out at 92.6 kph (50 knots), perhaps even 129.6 kph (70 knots). 

The vessel's design enables the craft to also be incredibly stable at speed, making it a perfect weapons platform -- especially for engaging other fast targets. The "Ghost" has also been designed with a wing-strut-detach capability enabling it to be partially dismantled for transport in large aircraft like the Boeing C-17 Globemaster III. 

How was the "Ghost" developed?

The attack on the USS Cole exposed the very real vulnerability of some of the most advanced, and expensive, pieces of military hardware on the planet using inexpensive craft and explosives.

The Ghost schematic
Schematic of the "Ghost". Source: Juliet Marine Systems

The ship's designer, Gregory Sancoff, took reports of the attack, and a 2003 wargame, called "Juliet", as inspiration to design a boat that could potentially counter such threats in the future. The wargame report, in particular, showed that a flotilla of small, high-speed boats could cause severe damage to a U.S. strikeforce. 

This, Sancoff believed, could be prevented using an innovative new type of marine vessel. 

When designing the vessel that would become the "Ghost", he also studied the existing literature on hydroplane racing boats and high-speed supercavitating torpedoes. A little later, in 2007, Sancoff founded Juliet Marine Systems, named after the 600+ page report, and began experimenting with mock-ups of his new ship at Portsmouth, New Hampshire. 

Under a shroud of secrecy (in part demanded by the U.S. Navy), Sancoff began nighttime field trials of the predecessors to the "Ghost". US officials also forbade his company from filing international patents or speaking openly about his work.

This would ultimately lead to a long legal battle in the court. After a series of trial and error, the prototype's hull successfully lifted out of the water in 2011, using its SWATH system. 

The Ghost SWATH
Source: Juliet Marine Systems

In the intervening years, Juliet Marine Systems has further refined the "Ghost's" design and is now seeking further funding to bring her to market. 

Could boats like the "Ghost" be used in the U.S. Navy?

That is certainly the hope of the "Ghost's" developers, however, to date, the United States Navy seems reluctant to actually commission any for its fleets. In fact, they have even attempted to prevent Juliet Marine Systems from marketing the "Ghost" to other third parties, barring the company from partnering with any other defense contractors and placing secrecy orders on its patents, meaning the company could not use or sell the technology to anyone. 

Years of legal battles have resulted, with a case finally being ruled in favor of Juliet Marine Systems, in 2018. 

However, several United States allies, like Isreal, South Korea, and Qatar, have expressed an interest in the vessel.

These are nations that are particularly reliant on fast coastal defense watercraft, and the "Ghost" would offer an excellent tool for interception and deterrent missions.

For Israel in particular, illegal arms trading by sea is a perennial issue. The "Ghost" would greatly improve their ability to police, intercept, and confiscate such shipments in the future.

South Korea is also constantly in need of patrolling their sea lanes to counter any intrusions from their potentially belligerent northern neighbors. Not to mention potential Chinese intimidation. 

The Ghost mission
Possible fit-out of the "Ghost" for reconnaissance missions. Source: Juliet Marine Systems

Qatar, an important American ally in the so-called "War on Terror", could also make good use of boats like the "Ghost" to also help keep the Persian Gulf waters clear of potential threats to commercial shipping. 

But, the future of the "Ghost" may well have nothing to do with combat-related activities. It is not beyond the realm of possibility for it to be used as a specialist highspeed VIP transportation, or even as a form of civilian mass transport.

With an estimated price tag of $10 million apiece, it could even find a market as a pleasure boat for the wealthy. 

Whatever the future has in store for the "Ghost" is yet to be seen, but it is certainly a very interesting and innovative piece of kit. Watch this space.

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