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back to article Hot bodies get super-slippery when wet

An Australian boffin says he has come up with a novel method for making things such as ship's hulls or torpedoes slip through water more easily. Professor Derek Chan of Melbourne uni suggests that it would be practical for ships to exploit the "Leidenfrost effect", named after its discoverer in 1756. This refers to the …

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  1. Anonymous Coward
    Boffin

    I remain highly skeptical

    A) Superheating the hull of the ship in question would take far more power than would be saved in moving the ship.

    B) I can only imagine the workplace risks involved for the sailors on said ship

    C) Pushing a ship through the water creates a tremendous amount of pressure at the bow and along the sides of the ship. That pressure would tend to overwhelm the vapor barrier unless you made the ship's hull even hotter.

    D) How long until this starts affecting ocean surface temperatures, especially in shipping lanes?

    E) how would the heated hull work in storms/high seas? Would it tend to exaggerate listing or the risk of capsizing because the vapor barrier presents less "good" friction that keeps the ship stable?

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  2. Oldfogey
    Boffin

    Stingray

    I presume Stingray used the cavitation effect to let it travel at several hundred mph? And maybe used red-hot Sting Missiles so they could go even faster, thus giving the Terrorfish no time to escape.

    "Anything can happen in the next half hour."

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  3. Anonymous Coward
    Anonymous Coward

    What would happen if ...

    ... you tried this on a hydrofoil?

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    1. Sandy106
      Reply Icon
      Mushroom

      Title

      Division by zero D:

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  4. Mikel
    Thumb Up

    Just blow bubbles

    No need for fancy heating.

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  5. John Smith 19 Gold badge
    Boffin

    Bottom line is power saved on engines > power used to create vapour layer ?

    Because this is a *dead* failure if it's not as essentially power = money.

    Water has both a high specific heat capacity and a *very* high heat of vaporisation. Getting this much water *to* boiling point is *nothing* compared to the energy needed to boil it.

    The torpedo situation might be a bit different. The benefits of speed might outweigh the cost of doing it. You might make life a bit easier by using a film heater (a metal foil pattern like a high power strain gauge) backed by an efficient insulator to dump nearly all the heat into the water.

    Strange to say it but the Russian torpedo with the rocket exhaust in the nose does seem to be the *simplest* way to do this. Anything that involves changes of state (solid->liquid->gas and vice versa) *always* involve large amounts of energy. They might be better off trying to build a porus torpedo casing and bubbling high pressure gas (at 100m the gas has to be > 10atm to escape and that rises 1atm for every 10m of water depth)

    Feasible in theory, but worthwhile IRL?

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  6. Anonymous Coward
    Anonymous Coward

    Imagine the order to sailor...

    Ok Expert Seaman Bones heat up your torpedo and shoot it in the direction of the incoming weapon.

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  7. Mike Flugennock
    Paris Hilton

    Sizzling speedy torpedoes?

    Congrats, El Reg; you've outdone yourselves again.

    So, hot bodies get super-slippery when wet? Who'da thunk it? Ooooh la la, baby.

    Paris, because she knows a thing or two about sizzling speedy torpedoes.

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