MINE SWEEPING.

Star (Christchurch), Issue 12637, 23 May 1919, Page 8

MINE SWEEPING.

, ' * —-. :■;.. . WORK OFF NEW .ZEALAND ' , coast! .-*.. [From Otb Oobjlesfokdent.] WELLINGTON, May 22. As the work of mine sweeping off the, coasts of New Zealand has been completed for thei a tire of the’ taiued from Captain Hall Thompson, Naval Adviser, interesting details re-; garding' its scope. Captain Hall; Thompson expressed appreciation of the: services of-the crews of the two trawlers employed. They weretaken over with the vessels, the Nora Niven and Simplon. They had no knowledge of the dangerous task, but they swept, two minefields .efficiently. . There was no accident due to enemy mines; .'.Unfortunately one man was lot overbbard froth the Simplon during a gale j and another had to undergo amputation of a foot as a result of an accident in port*, The trawlers swept up a number of mines, the total accounted for, including those exploded on beaches,- being fopty-sovep. out of sixty laid by'the euemy. Some naval rating "were placed, on,.the .trawler ,but these men' nadno practical experience of mine sweeping, -as this duty only arises during war time., The work had to; commence quite without knowledge where mines were laid, but a comparison of the plans of the suspected mine fields - with informasupplied by the .Germans rafterthe armistice shows that the naval ma T. er y accurate, guess! and .their prohibited . areas , completely ■■ covered the danger spots. “ When We got German information,” remarked .-Captain Hall Thompson, / ‘ it. wa s practically word for word with what was: plotted) out, showing that the .mine'sweepers did their work efficiently, . Operations commenced simply :<in the assumption that there was a mine field somewhere. Exploratory sweeps: showed; that, there were two. ’ One-line; of mines, ‘ eighteen miles in extent, ran in a north-wes-terly direction from Cap© ■ Hooper, off Nai-th Gape, Which would intercept the courses of vessels coming either 'from westward or frpnl .the Three Kings to tfie North Cape.; A : -danger Zone - was taed and shipping- were. directed to keep outside the hundred fathom Tine, winch took vessels tlurty miles dear of North Cape.' “ The second minefield covered a line approximately twenty-five miles long off Cape Farewell light to intercept ships nmnmg up the West Coast-into Cook (strait, or coming from Sydney hr Melbourne. In this ca S a too.direo toons from the naval authorities took snips clear of the dangers. The method' operating whs’’ id _ mike exploratory sweeps until more .than one mine had been discovered, when the line ot direction could be plotted and. followed up. Both minefields were exposed to bad weather, which considerably increased the difficulty of the work’. Thcsa fields were most difficult to clear, as the mines were laid in deep water, there was no chance of bottom sweepmg as earned out in shallow fields off the English coast, where it is possible to work with eight trawlers' abreast, but this is out of the question in New Zealand. The naval authorities have complete scale drawings of the mines. It is one good point in favour of the Germans that the mines were designed in accordance with international law, so as to become harmless on breaking loose from the moorings, hut unfortunately, although gear was fitted for disconnecting the firing' apparatus from the charge of 291b of explosive in the mine, it easily got out of order through rusting, and was not effective. A mine was fired by contact with one of the five horns fitted round the top. These were made of lead and could be easily colapsed on pressure. Pitted within the leaded horn was a small tube of acid, which was cracked on contact and allowed the contents to saturate a small electric battery, thus creating a current and instantaneously exploding the mine. Each hom was fitted with this system of electrical firing. The whaling steamer Hunauui was employed for tie final sweep, and the Admiralty now is sending out to New Zealand two mine-sweeping sloops, specially built for this duty. They will operate in the two minefields and give additional security to shipping, hut for the present, the barred zofie still is observed. Captain Hall Thompson expressed n hope that when the authorities consider the issue of war medals the men who did good work in minesweeping off the ; ew Zealand coast will get recognition