of the Dutch Royal Family to the UK. The DWI was used most successfully in the Mediterranean Theatre, particularly over the Suez Canal and Alexandria Harbour. Their use revealed the limitations of the technique, in that it only works effectively in very shallow water (such as canals and harbours). From about 1943, German Junkers Ju 52 transports were similarly converted. Blohm & Voss BV 138 MS tri-motor flying boats were also used for this purpose. The MH-53E Sea Dragon helicopter is used primarily by the United States Navy to tow several types of mine hunting or mine sweeping gear through the water. It replaced the earlier, RH-53A and RH-53D variants of the Sikorsky CH-53 Sea Stallion. Other examples of minesweeping helicopters include the RH-3A variant of the Sikorsky SH-3 Sea King, as well as the Mi-14BT variant of the Mil Mi-14 and the MCH-101 variant of the Augusta Westland AW101. See also Minehunter References External links Mine warfare Mine action