GUIDING SHIPS

Taranaki Daily News, 3 September 1921, Page 11

GUIDING SHIPS

SOME RECENT INVENTIONS. Some of the recent developments in navigational aids were touched upon in a lecture given in London lately by Dr. C. V. Drysdale, Scientific Director of Admiralty Research. The lecturer said that directional wireless had proved a useful method of enabling a ship to find its bearings with reference to two or more stations. The device of submarine sound ranging comprised two methods. ' In one, which was called “multiple sta- | tion” sound ranging, an explosive charge j was dropped from the ship, qnd the posi- | tion located from a shore station by the difference in times of arrival of the ;

sound at receivers near the shore. The position was worked out from these observations, and could be signalled to the ship. An alternative method was wireless acoustic sound ranging, in which a ship could determine its position relative to a single fix-ed station if that station sent , out wireless and sound impulses simultaneously. The distance from the I station was determined by the lime be- 1 tween the reception of the two impulses, and the direction could be found either ! by the directional wireless receiver or by a directional hydrophone. For the navigation of harbors and channels in fogs. Leader gear had been devised, consisting of laying a submarine (cable along the channel and feeding it with alternating current. The ship was provided with two coils on tne two sides, connected successively to an amplifier and telephone set. The current was interrupted to form signale. and these signals could be heard on the ship's telephones, being stronger ou the side

lon which (he cable lay. It had already 1 been found possible to follow a cable for I n distance of 30 to 40 miles full speed I at a fairly definite distance on one side oi it, so that out-going and incoming ships would be able to pass without collision. As regards the avoidance of obstacles, such as icebergs, the most promising method appears to be by acoustic echo, and devices had been developed which enabled powerful beams of sound to be sent out and echoes received from objects at considerable distance. Experiments had not yet been made with thia device upon icebergs, but the success obtained with them in the detection of other obstacles led to the hope that they might solve the iceberg danger.