Juliet Marine’s “Ghost” Ship Emerges from Stealth Startup, Gears Up for War

6/21/12Follow @gthuang

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a trade secret. But the propulsion system, which he says generates 30 percent more thrust than any other propeller-based system, essentially “boils water underwater and generates steam vapor.” (I take this to mean the pressure directly behind the propeller blades is so low that the liquid water there “boils” off and becomes a gas—hence the bubbles.)

After doing some digging in the literature, I asked Sancoff whether what’s in the patent filing is really how it works—in terms of how the Ghost creates its mysterious supercavitation. His answer: “No.” (OK, so there’s more to the story here. But you know when you’re supercavitating, he says, because the engine efficiency actually improves as you go faster.)

In any case, the overall design makes the craft go fast, but Sancoff isn’t making any public claims yet about exactly how fast. “We don’t talk about speed, how many weapons [it can carry], or how far we can go,” he says. Yet its rumored speed is at least 80-100 knots—over 100 mph. That’s not going to challenge the top speedboat records—there have been hydroplane efforts (riding on the water surface) that have exceeded 200 mph (174 knots) and even 300 mph (261 knots), some with fatal results—but the Ghost is faster than any previous underwater vehicle, Sancoff says.

What’s more, he says, the Ghost provides a much smoother ride than what Navy SEALs are used to; many of them blow out their backs from the bumpiness of their boats, he says. “Our boat does not have impact from the waves. We cut through the wave,” Sancoff says. “That is critical science.”

Hydrodynamics experts I’ve talked to say the main challenges of such a craft are controlling it, stabilizing it, and making it quiet. Going superfast in a straight line might be doable, they say, but any sort of turning or maneuvering must be done very carefully, because if the bubble layer distorts or breaks down at high speeds, tremendous water forces will come to bear on the foils, which can be catastrophic.

To steer itself through the water and maintain stability, the Ghost uses four movable flaps on the front of each foil and four on the back of each foil, for a total of 16 flaps. (The flaps reach through the thin bubble layer into the surrounding water.) The struts are adjusted to keep the command module out of the water, and the foils stay submerged, so waves at the water surface should only hit the struts, which have a small cross-section.

“It’s computer controlled, like a modern F-18,” Sancoff says. “We’re boring what looks like two wormholes underwater, and we’re flying through foam.” Sancoff himself has been test-driving the ship over the past couple of years. “I have been learning an entirely new craft since then. It’s a totally new experience,” he says. “Just because you drive Grandpa’s boat, you’re not going to drive this one. It’s more like a helicopter.”

As for the craft’s audio profile, Sancoff is proud of its “silent propulsion” system that includes a sophisticated muffler system for the engines. You can’t hear it from 50 feet away, he says.

Coming Out of the Night

With any grand invention like this, some outside experts are going to be skeptical. “I wouldn’t say it’s not going to work. But I have concerns,” says Gary Balas, head of the department of aerospace engineering and mechanics at the University of Minnesota. Balas is an expert in flight and underwater control systems, but his main objection is that the propulsion system of the Ghost, with its forward propellers, is very unusual … Next Page »

Gregory T. Huang is Xconomy's Deputy Editor, National IT Editor, and the Editor of Xconomy Boston. You can e-mail him at gthuang@xconomy.com or call him at 617-252-7323. Follow @gthuang

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  • PJS

    video or GTFO

  • Logos302

    It’s the Defender from Decent :).

  • Paul van Dinther

    Wow, a fleet of these vessels could finally clean up the waters around Solalia

  • esorf

    The point of a patent is that in return for protection of your intellectual property, you have to share how it actually works.

    • jen g

      thank you.

  • Geowash01

    Two points:
    1- Outrun torpedoes? Until they come with supercavitation, too. (Besides tracking this thing will be easy, and it can’t out run a bomb.)
    2 – How will it see? Speed and boundary layer effects likely make all current acoustic sensors OBE.

    • atypicaloracle

      1. Supercav torpedoes already exist and have for well over a decade. They’re expensive, there aren’t many countries that developed them, and they can’t turn very well. Also, the part of the boat that is in the water (and thereby vulnerable) is stated to be relatively small – this would be like shooting a bullet with another bullet.

      The vehicle is designed for stealth, so tracking it with what? Aircraft? If the thing’s intended use is for naval interdiction against small craft attacks, then you are flying an observation aircraft near a naval group. That won’t end well for the “trackers.”

      I also have no idea what you mean by “it can’t outrun a bomb.” I’m not an air warfare expert, but I can only assume that hitting a 60′ long target going 80 miles per hour with any form of air-dropped ordinance is going to be insanely difficult.

      2. Well, aside from just looking out the windows… I don’t really know a great deal about how an object going 80-100 miles per hour generates enough of a boundary layer effect to blind its own radar, but apparently jet fighters going several multiples of the speed of sound manage it somehow. Technology is amazing.

  • guest

    “Ghost cannot be hit by a torpedo. You would have to shoot it with a gun.”

    Unless you had supercav torpedos. :-)

    • Guest

      Unless as mentioned in the article the torpedos are not able to manoeuvre as well, a small, nimble and fast craft may be very difficult to hit.

  • ddevine

     Hey guys I just invented a $5000 flying car with perfect handling. You should believe me because nobody lies on the internet.

    • jen g

      dude, I’m around if you wanna chill in your fling car.

      again.

      • jen g

        flying

  • Johnbjormn

    The not hit by torpedoes has as much to do with extremely low radar profile as it does with speed — reread the article — or read other sites on this boat

  • Z Bomb

    Supercav torpedos will be the next invention now that this is out there. Bullets were followed by bullet-proof vests. Rockets were followed by rocket-killing devices. Supercav boats will be followed by supercav torpedos. It’s inevitable.

    • Dfgadfg

      Read the article. It’s already been done.

  • RandomDude

    As mentioned, they already have supercav torpedos,  That’s how the Kursk got sunk

  • http://www.stumbleupon.com/stumbler/mhenriday/ M Henri Day

     Vapour/bubbleware ?…

    Henri

  • Valid

    If this ears Up for Warthen it should be destroyed or bombarded by NATO becase it is threat to to world.

  • SoundBytes

    Ever hear of Ekronplan? Or a hydrofoil? This craft seems to be a hybrid of the two but, why?

  • http://profiles.yahoo.com/u/ENWYFOIUQ5LONZ3AF5V4TPFUS4 zensatori

      What  bout  objects  such as  deadhead tree trunks? Hyrafoils can  have a prob  with  those , hard  to spot  even on radar just the vertical trunk has a very small patch.

  • jack

    ha, just what we need, billions more on military spending. good luck with that,
    let the h strait close for all we care.

    • mojo78

      Yeah, because we all know the defense of a nation isn’t necessary, especially these days with all of the super nice people of the world.

  • Kayefsee1

    Here is the secret of the Ghost – the props had to be in the front cause if indeed the torpedos are at super cavitation stage (usually at about 60 knots) a rear driven prop would be caught up in the air cavity tail producing negative thrust.The props at front help keep induced bubbles injected directly behind prop in place even below 60 knots. but props are no good, i know i have a similar craft with superior drive with much less power oh and yeah its a super cavitation vessel and much more.

    • jen g

      I’m pretty much around if you want to spin in your ghost.

      i had to say that.:)

  • blipfliptipper

    Imagine a fleet of these going up against the PLAN! A whole bunch of Chinese scrap metal sinking to the bottom of the ocean is what you’d get from that. Good stuff.