shaken ship usually sinks quickly, with hundreds, or even thousands of small leaks all over the ship and no way to power the pumps. The crew fares no better, as the violent shaking tosses them around. This shaking is powerful enough to cause disabling injury to knees and other joints in the body, particularly if the affected person stands on surfaces connected directly to the hull (such as steel decks). The resulting gas cavitation and shock-front-differential over the width of the human body is sufficient to stun or kill divers. Control surfaces and hydrodynamics Control surfaces are essential for a torpedo to maintain its course and depth. A homing torpedo also needs to be able to outmaneuver a target. Good hydrodynamics are needed for it to attain high speed efficiently and also to give a long range since the torpedo has limited stored energy. Launch platforms and launchers Torpedoes may be launched from submarines, surface ships, helicopters and fixed-wing aircraft, unmanned naval mines and naval fortresses. They are also used in conjunction with other weapons; for example, the Mark 46 torpedo used by the United States is the warhead section of the ASROC (Anti-Submarine ROCket) and the CAPTOR mine (CAPsulated TORpedo) is a submerged sensor platform which releases a torpedo when a hostile contact is detected. Ships Originally, Whitehead torpedoes were intended for launch underwater and the firm was upset when they found out the British were launching them above water, as they considered their torpedoes too delicate for this. However, the torpedoes survived. The launch tubes could be fitted in a ship's bow, which weakened it for ramming, or on the broadside; this introduced problems because of water flow twisting the torpedo, so guide rails and sleeves were used to prevent it. The torpedoes were originally ejected from the tubes by compressed air but later slow-burning gunpowder was used. Torpedo boats originally used a frame that dropped the torpedo into the sea. Royal Navy Coastal Motor Boats of World War I used a rear-facing trough and a cordite ram to push the torpedoes into the water tail-first; they then had to move rapidly out of the way to avoid being hit by their torpedo. Developed in the run-up to the First World War, multiple-tube mounts (initially twin, later triple and in WW2 up to quintuple in some ships) for torpedoes in rotating turntable mounts appeared. Destroyers could be found