Page 159 - British Inquiry into Loss of RMS Titanic Day 19 - 22

Committee have any recommendations to make with reference to bulkheads which would, in their opinion, contribute to the safety of life at sea. “In approaching these questions we found that but little definite information existed concerning them; and although we have had much valuable and interesting evidence from several well- known experts, we thought it necessary to have recourse to actual experiments, carried out under our own supervision, in order to obtain the information contained in Appendices A and B to our report. These experiments have been proceeding continuously for about a year, and our endeavour has been to arrange the results in a practical form. “As regards the sizes and classes of vessels assigned to the several grades of subdivision, in our reply to para. 2 we may observe that our conclusions in this respect are the result of much deliberation, and are based on what we deem a fair adjustment as between loss from broken stowage on the one hand, and the greater safety on the other, resulting from improved subdivision. In judging of this matter, we have supplemented our own practical knowledge with reports and evidence from representative shipowners and shipbuilders, as to the minimum length of hold admissible in various trades. “We now proceed to answer the questions categorically:- “1. Vessels may be considered able to float in moderate weather with any two adjoining compartments in free communication with the sea, if fitted with efficient transverse watertight bulkheads, so spaced that when two such compartments are laid open to the sea, the uppermost watertight deck to which all the bulkheads extend, and which we will call the bulkhead deck, is not brought nearer to the water surface than would be indicated by a line drawn round the side at a distance amidships of 3/100ths of the depth at side at that place below the bulkhead deck, and gradually approaching it towards the ends where it may be 3/200ths of the same depth below it. This line we may call the margin-of-safety line. “ With longitudinal bulkheads in combination with transverse bulkheads the vessels should not, under the above conditions, list so as to bring the deck on either side below the water level. Vessels in which the bulkheads do not extend to a continuous deck require a modification of the margin-of-safety line, as to which see Appendix A. “The arrangement of plane transverse bulkheads necessary to satisfy the above condition, may be determined with the aid of the curves and tables in Appendix A, or by separate calculations in accordance with the assumptions made in that Appendix. “These curves and tables show the maximum spacing of such bulkheads permissible in vessels of various descriptions and under various conditions at any point in the length measured along the loadline from the foreside of the stem to the afterside of the sternpost, in connection with any given freeboard measured from the bulkhead deck. The freeboard to be used is not necessarily that required under the Merchant Shipping Act, 1890, but may be any freeboard which, on the application of the shipowner, may be registered by the Board of Trade. Such freeboard we will call the bulkhead freeboard, and the corresponding loadline the bulkhead loadline. With the tables so arranged it is, we submit, unnecessary for us to frame rules with regard to the proportion of freeboard in relation to the size of the vessel. “The tables have been constructed for vessels carrying coal cargoes, but it will be obvious that a vessel whose bulkheads are spaced on the assumption that she carries a cargo of coal, will not be able with equal safety to carry an equal weight of a cargo of greater density - say, pig iron. “There are thus two methods of proceeding, either of which would enable the condition specified in the Boards question to be fulfilled, viz.: (1) bulkheads must be spaced for cargoes of some specified density, and the vessel will then be able to take full cargoes of such or any less density; or (2) bulkheads must be spaced for some average cargo, and when a cargo of greater density is carried, the vessel must have a greater freeboard, i.e., must carry a less weight. “With a view to measuring the effect which difference in the density of the cargo has upon the