MARINE EQUILIBRIUM.

Dominion, Volume 3, Issue 819, 17 May 1910, Page 2

MARINE EQUILIBRIUM.

[ THE DUCO PUZZLE. | PRINCIPLES OF STABILITY. IVEKY INTERESTING EVIDENCE. Further evidence as to the stability c the Duco, when she left on her last tri to the Chathams, was heard by Mr. Ju; tice Chapman and a special jury <: twelve at the Supreme Court yesterday The Wellington Harbour Ferries, Limite - (represented by Mr. C. P. Skerrett, K.C and Mr. F. G. Dalziell), claimed from tli Corporation of the Royal Exchange A< suranco (represented by Mr. J. H. Ilosli ing, K.C., Mr. A. A. S. Men tea th, aiv Mr. W. H. D. Bell), the sum of c£so insurance money on the Duco, plus in terest and legal costs. . Other claims ar pending, the total sum for which th Duco was insured with several companie being <£2000. The case was treated a turning mainly ou the question whethe the Duco was seaworthy when she let on her last voyage. Alfred Alexander, in charge of the Mn rine Department at the Post Office, sail the mails put on the Duco were esti mated at 7cwt. Mr. Zohrab's Evidence, 1 Edward Goodwin Fortescue Zohrat manager of the plaintiff company, sail the vessel was insured for £2500. He value in the books of the company wa £5300. The value was written down ii 1905, and since then G per cent, had bee; written off annually. He did not knoi her original value, but she was takei over from the former owner, Mr. J. II Williams, for £9000. There had sine been a capital expenditure of £1300 upoi her. _ The company complied with ever; requirement of the Government in con nection with the alterations made befor going to the Chathams. Captain Abran was responsible for the loading and tiii quantity of coal carried on the trip' b the Chathams. The concrete blocks wer also the result of a suggestion of Cap tain Abram's. The fish boxes placed oi board were estimated by witness t< weigh two tons. The placing of th. water on board would be determined b the master and engineer in conference He believed that the Duco left on hei last trip tit 1.50 on September 7, 1909 Ho saw her off. Her draught was Bft forward and lift. aft. Witness watchec the Duco round the point, and then Cap tain Bondatl came to him on the wliar and asked: "Where's the Duco?" Witness 'told 'him he was too late, and the captain replied: "I'm sorry; I shoulc like to have seen her." Captain Bendal also remarked that there was a southerly coming but he did not think it would Piuch, and Captain Abram would sec • £ Captain Abram 'had the reputation ot being a very cautious man. The Government Inspection. - To Mr. Hosking: Mr: Calvert, the Government Surveyor of Ships, made one suggestion about a ventilator and this was! complied with. Witness, believed Utev also renewed a steering chain at Mr. Calvert s request. He did not remember that Mr. Calvert made any other suggesCaptain Stringer • made a suggesi A - ,vl ' ness provision the boats, and this was done, though not required by law. They also renewed the mastK ! 1 /s °n " ls suggestion. The above were the suggestions made by the Government oDicers to witness personally. The officers usually spoke direct to the master Ot the ship. Captain Abram and the whole crew were "on lay," i.e., they were to receive a percentago of the cash proce£ds of the venture. Apart from the mails, and tho coal, etc., put on board tor the owners, the only cargo taken for the Chathams on her last voyage was a uag of grass seed. Captain Abram and the Owners. i t lras aware that Captain Abram hart been given to-understand by. members of the directorate that the success, mnl" M Vl 4?' "vi*"'® Tenturo "would make all the difference to him. The chairman had not suggested to him that it would be better to have as captain a more active man than Captain Abram. witness and the chairman discussed the question of how much coal they could get down to the Chathams bv the Duco horself. They probably told Captain Abram to take ns much as ho could safely carry. The idea of the fishing enterprise was first suggested to the company by Captain Abram. It was reported to the company that the Dnco's bunkers could not carry sufficient conl. A letter from Sampson, a clerk in tho company's employ, who went on holiday leave on the Dnco's first trip to the Chathams was received bv witness. It comprised the suggestion that more coal should be carried, and a suggestion that a more active , and younger man should take the nlace of Captain Abram. Mr. Hosking asked the witness whether any claims had been made against- tho company by the relatives of any of those on bo:u (I thti Duco oh her last trip. ,„Tho question was obieeted to by Mr. okerrett, and disallowed by his Honour. Some Personal Questions, Mr._ Skerrett: I am going to ask a question which I have hitherto abstained from asking; hut all kinds of prejudice seem to be dragged into this case. .Whose signature is this on tho insurance policy? Witness: "O. R Bendall." . , W' m L. rolation is 116 to Captain Bendall?—"Son. Ia he not tho manager of the insurance company?—"He is a representative of the company. Is there any truth in the. suggestion made by Mr. Hosking that any pressure lvas brought to bear upon Captain Abram m regard to tho movements of the Duco on her last voyage?—"Absolufely none." Itave you any knowledge of any suggestion of that kind having been made to Captain Abram?—"None." \ou say that you and tho "chairman of your company and Captain . Abram had' many conversations?—" Yes." And was jin.v topic of the kind which was suggested by Mr. Hosking, referred to in any of those conversations?—" No." Captain Abram's .interest was confined to his wa?es. and his interest in the lny"?—"Yes." And he would get that whatever was pecuniary success of the venture'— Yes. Mr. Hosking: Is nnt Captain Bendall a shareholder in the Perries Company?— A small shareholder." Captain Smith in the Box. George Gordon Smith, Superintendent of Mercantile Marine at Wellington for several years, and an ex-master mariner, said the Duco took out her articles before him prior to sailing for tho Chathams. hho was required to carry at least one ablo seaman, and she carried six He saw her leaving on tho last trip, and sho appeared to be in very good trim. If tho cargo was properly secured, it would bo safo to carry it. He considered that-tho Duco, loaded ns had been described, was fit to go to the Chathams, if the ordinary precautions were taken. William Butler, ship's carpenter, in the employ of tlie plaintiff company, said ho worked on tho Duco, making the alterations for the voyages to the Chathams. I ho tank fitted into a bed, and pressed closely on u irrating and against The towing beam. The tank was lashed so that, it could not shift either way, and ho thought it was pretty safe before lashimr. An Expert and a Blackboard. Draycot Birkett, naval architect, with the aid of a blackboard explained various technical matters put to him by counsel—centre of gravity, centre of buoyancy, effect of metacentric height and stable, neutral and unstable equilibrium. Ho stated the general principles of stability whicli could not be departed from. Ho said that when asked to investigate (lie stability of the Duco he had doni so. The metacentric height was 2.34 ft. A metacentric height of 15 to 18 inches was considered enough for a ship of the. class of the Duco. If she had more, she would be a stiff ship. If less, she would have an easy roll. He had made his calculations on the accepted principles. He had also mndo calculations tor tho conditions when the Duco was working as u tug, and found that there, was then a metacentric height of 2.52 ft. Ho had oscertained that tho centro of gravity at that timo was 7,7ift.. above the

top of tho keel. He had taken Mr. M'Crae'ii calculation for tho height of tho inetaceutre. A Graphic Demonstration. At this stage, witness produced a model of the midships portion of a steamer, swinging on pivots running longitudinally. By hanging the model on pivots at different heights (representing the metucentre). the witness demonstrated that, when the mctacentrc was abovo the centre of gravity, the ship was stable (i.e., would return to the normal position after disturbance);' that when the centre of gravity and the metacentre coincided, the ship would have no tendency to right herself; and that when the metacentre was below the centre of gravity, the ship was unstable, and would turn turtle and remain bottom upwards. In further reply _to Ifr. Skerrett, the witness stated that with the centre of Gravity and the metacentre as he had calculated them to have been when the Duco left port, she was seaworthy from tho stability point of view. * His Honour: But if you have a green sea on board it alters that? —"Yes." You don't alter the rule, but you alter the fact?—" Yes. That is so." Mr. Skerrett: Then your evidence is lliat you have ascertained that tho metacentric height was 2.31 ft., which was in ■■■xcess of what is admitted by all the authorities to be sufficient for a vessel of this kind ?—"Yes." Witness also said that the metacentric height of passenger boats was never very great, because, if it were, they would recover tiie vertical position with a jerky motion. He knew of passenger steamers crossing the Atlantic with only one foot of metacentric height! Expert Cross-examined. Mr. Bell cross-examined the witness on tho sources of data upon which he had mado : his calculations concerning the Duco. Witness said the greater part of : s calculation of tho centre of gravity wan based on estimates of various weights and various distances. An error of two feet in the height of the centre of gravity as given to him would result in an error of two and a half inches in his calculation of. the metacentric height. He had not made any calculation to show how far the Duco could roll and still recover herself. It was impracticable to do so. Do you agree with this statement in Walton: "Valuable as a knowledge of metacentric stability of a vessel may be under certain circumstances, yet it alone is no safe criterion as to a vessel's resource of safety when exposed to severe weather and. subject to excessive heelimr forces ?—"Yes." Witness also agreed that a vessel with' a large metacentric height may have a small range and be unsafe at large angles of inclination. He made no calculation to find whether the Duco was safe at large angles of inclination. There was no mathematical certainty about her stability if a large wave, came aboard in a beam sea, inasmuch' as it was impossible to ftll the quantity of water on board, or the angle of inclination. The case' will be resumed at 10.30 this morning. |