HAWKE-OLYMPIC COLLISION.

Otago Witness, Issue 3017, 10 January 1912, Page 7

HAWKE-OLYMPIC COLLISION.

NEW “SUCTION” THEORY. (From 01 - b Own Coruescondent.l

LONDON, November 24. Tho recent Hawke-Olympic collision in the Solent hae been cairried to the law courts, and there are cross-actions for damages by the Oceanic Steam Navigation Company and the Admiralty. The most interesting part of tho evidence to seamen is the new theory of suction put forward by tho. Admiralty. The Olympic attributes tho collision solely to tho negligent navigation of the cruiser, which, it is alleged, as tho overtaking vessel, failed in her duty to keep clear, and when abeam on the starboaic! side improperly starboarded her helm, or aJlowed her. head to swing to port. Tho Admiralty’s case is that the Hawke, on a steam trial, was proceeding up the Solent when the Olympic, in coming out of Southampton Water, took a sweep too wido round the West Brambles, and brought herself close over the port side of the cruiser. The result was that the suction created by the Olympic caused the cruiser to swerve to port, thus bringing about the collision.

Captain Edward John Smith., commander of the Olympic, cross-examined by Sir Rufus Isaacs, said it never occurred to him that there was any danger of the Hawke being sucked in, but supposing tho Hawko was within 100 yards, he thought there might be a possibility of that force operating. He had never observed any suction in the Ambrose Channel. Before tho Olympic he commanded tho Adriatic, and had never experienced suction. Ho had been in the Mersey with the Adriatic. George Bowyer, the pilot, said ho had never yet experienced a case of suction. The Olympic could have given the Hawke more room, but there was no need, as there was plenty of room fp-r both ships. .SPEED AND SUCTION. Captain John Pritchard, formerly commander of the Cunard s.s. Mauretania, said ' that that vessel had a tonnage of 35.000. and a speed of 26 knots. In narrow channels he went slow or at half-speed Have you over in your career experienced suction or vessels interacting?—No. In the Ambrose Channel, which was ■ 000 ft wide, witness said ho worked at from 12 to 14 knots when the weather was tine. Gross-examined ‘by Mr Aepinall: How close do you pass vessels there?—Within 200 ft. At a speed of not more tlian 12 or 14 knots? —Not more than that. You don’t care to get nearer than 200 ft? —No. You would rather have more than 200 ft if you could get it? —No; one does not want more. Have you ever tried passing a vessel nearer than that?—Yes, wo 01100 passed the Hamburg-American steamship Ainerika at a distance of 150 ft, we making 15 knots. What was she making?—About eight knots. You would not like to go past her at any pace?—No. I don’t think it would be safe. Why not?—A collision might occur. By suction or what?—l could not say. She might not steer as well as wo. Tho President; You say it would not bo safe to pass at 18 to 20 knots. Now, what are the elements of danger?—A ship not answering her helm in such narrow waters. Not suction, or interaction? —No, my Lord. I have never scon that. What is it in a narrow channel that makes it more difficult to answer helm?— Because of the shallow water. If another ship is passing at the time you take her water from her. Mr Lewis, a first-class Liverpool pilot appropriated to rhe Lcyland Line, and holding a license for the Manchester Ship Canal, said that on several occasions while piloting vessels ho had boon passed by tire Lusitania and the Mauretania in channels of the Mersey, and on some occasions they had not been more than bOffc or 60ft away. What have you been steaming at at th-s time? —About 12 knots. Have you ever with your own large ves sols known, other vessels to bo affected oy you? —No. THE ADMIRALTY CASE. Captain Blunt, of HALS. Hawke, said it had always been his view that suction wavs the cause of the collision. Ho could Tiot lay how far a vessel had fo bo from a l ar -r Q (,lnn like tho Olympic to escape tho effect of suction. In the case of an ordinary ship he should not like to ho nearer than 50 yards. In this case ho was about 100 yards from tho Olympic. Sir Samuel Evans (the Judge) and tho principal counsel have attended at Ted-

dinglon to witness experiments carried on in a large tank in explanation of the suction theory. THE TANK EXPERIMENTS.

Georg© Baker, superintendent of the “ William Frondo ” tank, at the National Physical Laboratory at Teddington, said that the tank was used, for the purpose of making scientific investigations. He was instructed by the Treasury Solicitor to make experiments to ascertain the relation of these ships one to the other. The models were mad© of paraffin wax, 1-44 of the size of the original ships. The tank was 549 ft in length, 30ft wide, and 12ft 4in deep for 490 ft. Subject to scale, ho reproduced the actual draught at the locality of the accident as near as he could from information received from the hydrographer to the Admiralty. A travelling carriage was provided for the purpose of towing the vessels through the water. There were two planks, the Olympic model being so arranged that it could not move sideways. The Hawke model was not fixed at all, it could do what it liked. Was an effort made to tow the Hawke straight and eliminate any tendency to yaw ?—Y cs.

Before starting, he looked at the problem from a theoretical point of view. MODELS SWERVE INWARDS.

Ho set tho carriage at 18 knots, or 279 ft a minute, for the models. On the occasion of the first experiment there was no helm on the Hawke, the result being that the model swerved very badly towards the Olympic. At the second experiment tho Hawke was given live degrees of helm, put up to 20 degrees in one second, a helm which should turn tho vessel away from tho Olympic. Tho Hawke, however, turned in towards the other ship, the swerving being a little slower than on tho first occasion. For tho purposes of these two experiments the fore perpendicular of tho Hawke was 510 ft abaft tho foro perpendicular of the Olympic. The Olympic was then put so that the Hawke was 490 ft aft of her, and the Hawke sheered away. They next tried it in deep water, and the sheer in was about the same os the sheer out in the former place. Another experiment was an,!!do in shallow water, with the Hawke 550 ft aft, and she swung in and came bodily towards tho Olympic. The same experiment was tried with five degrees of helm, when tho sheer was outwards. They then tried the Hawke without the Olympic and without helm. Tire cruiser swerved in towards tho place where the Olympic would have been. To what did you attribute this sheering of tho Hawke?-—I think it must have boon caused by the bottom when tho model was there alone. Wo have- tried it again and again, and it has always had the same effect in the shallow, but not in the deep. It is attributable to tho character of the shoaling of tho water. To what did you attribute the failure of tho Hawke to continue in a straight line when being towed in company with the Olympic?—The influence of the Olympic. CHANGE OF PRESSURE. What force?—A 113’ ship's movement through the water is accompanied by change of pressure. In tho centre there is a held of reduced pressure, and when in shallow water that increases. When one vessel overtakes another, and is so placed that the bows feel tho reduced pressure and tho stern is in tho held of increased pressure, tho bows will turn in and the stern will move out. Cross-examined by Mr Laing; Is this the first series of experiments you have conducted on the suction theory?—Yes. Did not your experience show you that there was a natural bias on tho cruiser?— No.

But .she did exactly the same thing when the Olympic was not there as when she was? —Not in deep water. Docs not that show that the Olympic was not really affecting the Hawke?—No, it shows the other thing. In some of the experiments tho Hawke lurried tho opposite way?- Yes.

Away from the Olympic? Yes. What does that go to show ’! —That tho stern of the Hawke answers more readily to tho suction influence than do tho bows; that she would sheer in bodily, but that she would sheer out as the stern was brought in. The President; Does tho fact that there wore no propellers on the Hawko make any difference? —No, I don’t think so. The screws, if there, would send the water back faster and make the rudder net. Wo have tried the Olympic with the screws not working. .Sometimes I thought it made a difference, and sometim'o9 not. Does the presence of a steep and upright bank make any difference ? I think it would.

Do you know that vessels in the Kiel Canal keep as far away from tho banks as possible, and get as near to each other as possible when passing?—! have never hoard that they deliberately get away from the banks.