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"TAE MarRINE REVIEW attention to these pins and links, as later on he will give you an illustration of the power and peculiarities of high explosives when used for the purpose of cutting heavy masses of metal adrift under water. a The dredger is fitted with compound surface condensing engine, with cylinders of 25 in. and 51 in. diameter, and a stroke of 3 ft. She has two boilers, 12 ft. diameter by 10 ft. long, and*is also fitted with independent engines for driving her deck machinery fore and aft the vessel. As far as could be estimated the entire weight of the ves- sel was about 1,150 tons; the bucket ladder alone weighing between 60 and 70 tons. At the time of the accident she was chartered by Messrs. Pearson & Sons, the contractors for the new Queen's graving dock, etc, and was engaged in dredging and removing the wall of the old Queen's dock. This was a very difficult operation, and during its perform- ance it is supposed that one of the buckets took up a larger piece of granite than could pass through the center well, which in its passage upwards pierced the side of the port buoyancy chamber and allowed the water to rush in. The vessel having a heavy list at the time lost her equilibrium, and capsizing completely over to port, was only prevented from turning bottom upwards by the top part of the ladder or superstructure becoming embedded in the mud and sand- stone rock at the bottom of the dock. She was then lying past her beam ends and at an angle of 113 degrees. Divers were sent down to examine and they reported her lying hard down on the rock on her port side, clear of the wall she was dredging, about 15 ft. The buckets had fallen off the rollers when the vessel capsized, and were lying in a bunch at the bottom of the dock. Two plans of uprighting suggested themselves. The first was to close up all the lee hatches and other openings, and place the necessary number of steam pumps in craft alongside, then pumping out the lee buoyancy compartments and attaching counterpoise weights to the higher side, turn the vessel over by these means. The principal objection to this scheme was the amount of car- penter's work that would require to be done under water; but besides there were numerous other difficulties. The sec- ond, or alternative plan, was to parbuckle the vessel up by means of wire hawsers and lifting pontoons. This last plan was finally decided upon, and it then became necessary to approximately estimate the amount of power required to car- ry out this operation. After some calculations, which it is not the author's intention to trouble you with, it was de- cided that there was sufficient plant available to enable the work to be carried out in the last named manner, and a com- mencement was made. The first difficulty encountered was the getting rid of the buckets which were lying at the bottom of the dock, and the following expedient was adopted: The bight or center of the chain of buckets was slung by the divers, and the 30 and 4o-ton derricks of the Ranger and Linnet attached; the buckets were then hove up nearly to the surface of the water, but owing to the manner in which they were jammed it was found impossible to disconnect the pins and so release them. They were then lowered down again to the bottom of the dock and were eventually sepa- rated by explosives. On account of the close proximity of the vessel to the new dock walls it was dangerous to use heavy charges, and at the first attempt to sever the bucket chain only two pounds of gelignite was used, but owing to the heavy section of the wrought iron double. links, which measured 8% in. by 4% in., this charge had no effect whatever, so it was doubled and a. charge of four pounds then exploded. This proved perfectly successful. It is a curious fact, illustrative of the power of high explosives, that the charge was placed on the lower link and it not only severed this completely, but also cut the up- per link through in the same manner, although it was not - directly in contact with it. The operation was repeated as necessary, and the chain of buckets cut apart in sections of 3 or 4. They were then raised from the dock bottom by the salvage steamers. The author has no photograph showing the cut, but the next slide gives a view of some of the buckets after they were > landed on the quay. The remainder of the chain of buckets, © after being freed from the dredger, were dropped to the bot- tom of the dock and subsequently raised by the too-ton crane Atlas. The problem that next presented itself was how to secure standing part of the parbuckling wires. There was nothing on the higher side of the deck of the dredger in the shape of bitts capable of bearing the strain, and it was eventually de- cided to fit strops made of a double part of 6-inch wire rope, round the keelson in the upper coripartment, taking the ends - through the hatchways and openings in the deck, and shack- ling them on by means of specially constructed shackles to. the standing parts of the 9-in. parbuckling wires. Four of these were used and were hove under the ship by the salvage steamers Ranger and Linnet. Owing to the way the vessel was resting on the rock much difficulty was ex- perienced in getting these wires under her, the two steamers having to tow alternately at their utmost speed, thereby cut- ting, or rather sawing the sandstone rock away until the wires were in their required position. Sheerlegs were constructed on shore, composed of pitchpine logs 24 in. square, made in the form of a tripod, with a heavy casting on top to take the wire rope. These sheer legs were 25 ft. high, and weighed about 12 tons. After being erected on shore they were lifted from the quay by the Ranger and secured on the high side of the vessel as shown on the accompanying view. The end of a Q-inch wire rope was then secured by the divers to the extreme end of the dredging towers lying in the bottom of the dock, and taken over the casting on the top of sheerlegs to the quay wall. A 100-ton purchase was attached to this wire, and a steam winch with 9-in. cylinders, 12-in. stroke, secured .to the concrete on the dock wall, and supplied with steam from a portable boiler working at a pressure of 80 Ibs. per square inch. From the end of the crane used for lifting the bucket ladder on the fore part of the vessel another g-in. wire was attached by the divers, and the end taken to a 75-ton purchase on the dock wall, worked by another winch of the same power in a similar manner, and supplied with steam from a similar boiler. Two 6-in. wire ropes were then made fast to the immersed lower bulwarks of the vessel by the divers, and the ends carried across to the opposite side of the dock, where they were secured. These were intended as check ropes in case the dredger, on uprighting, showed any tendency to fall over the other way, and they had slack enough to allow her being uprighted. The upper or starboard buoyancy spaces being empty and clear of the water, would have offered a very considerable resistance to the righting operations when the vessel had been sufficiently turned for the lower part or bottom of these compartments to become effective as the operation brought them into the water, and it became necessary to de- vise some plan by which water could be quickly admitted into these compartments at the proper moment to destroy their buoyancy. It was decided to cut holes through the. bot- tom of the vessel, and as these holes would be resting on the flat rock when the ship was upright, and would have to be closed by the divers before she could be pumped out and floated, a plan had also to be schemed out so that they could be closed up readily from the inside, and the following meth- od was adopted: The two large buoyancy compartments had hatchways suf- ficiently large for a diver to get through to the bottom of the ship, and immediately under these hatchways two holes of 10 inches in diameter were cut through the shell plating