A CLEVER DEVICE

Hawera & Normanby Star, Volume LXXIV, Issue LXXIV, 15 February 1919, Page 5

A CLEVER DEVICE

FOR PROTECTION AGAINST

MINES,

One of the latest and, perhaps, 'most successful inventions for protecting ships in mined areas is to be seen on the steamer Port Hacking, now in Wellington (states the Post). This method of protection, known as the "Otter System," is worked in something the same way as a trawl net, with floats instead of the "otter boards," familiar to all connected with the fishing industry. Attached to the bow of the vessel, several feet above the water line, is a steel arm or boom, working on a swivel, with an eye at the end. This boom, when the mined area is approached, is lowered with a steel wire cable through the eye, which is below the water line. Attached to each end of the cable is an "otter," a torpedorshaped float with a | pair of wings, one of them weighted, and a set of tail planes which act a& rudders. In order to keep the cable submerged so ag to strike the mine mooring-chain, a hydrostatic ;valve, similar to that used in torpedoes, is used to operate the rudders and make the "otter" travel at the required depth. The "otter" is steered away from the side of the vessel by th© tail rudders and the wings. When a mine chain is struck, it runs along the cable as far .as the "otter," and is then caught in a V-shaped strong steel knife, which cuts it, allowing the mine to rise to the surface, when it can be exploded by rifle fire. This system is used only in depths under 100 fathoms, as mines are not moored to greater depths.