NATURE 



169 



THURSDAY, DECEMBER 24, 1885 



THE LOAD-LINES OF SHIPS 



THE regulation of the depth of loading of ships is a 

 matter that has received the attention of scientific 

 men and practical seamen during many years. It has been 

 hotly discussed in various quarters, and numerous disputes 

 have arisen over the attempts of the Board of Trade to 

 carry their views respecting it into practice. A long series 

 of debates and disputes culminated in the appointment of 

 a Committee by iVIr. Chamberlain, the late President of 

 the Board of Trade, to report upon the question. 



That Committee, now well known as the late Load- 

 hne Committee, had Sir E. ]. Reed, K.C.B., M.P., for 

 its Chairman, and reported to the President of the Board 

 of Trade in August last. The Report was unanimous ; 

 and was conclusive as to the practicability of framing 

 general rules concerning freeboard which will prevent 

 dangerous overloading without unduly interfering with 

 trade. The Committee's rules have been accepted by 

 the Board of Trade and Lloyd's Register Society ; 

 and at the same time they have received the general 

 approval of ship-owners. 



Like many answers that are given to questions, the 

 Committee's Report states the opinions that were arrived 

 at, but does not give the reasons for them. This natu- 

 ral omission has been supplied by a paper read before 

 the Society of Arts on the nth inst., by Prof Elgar, of 

 Glasgow University, who was a member of the Com- 

 mittee. Prof. Elgar said : — 



" It is necessary to understand the causes of the differ- 

 ences between the various types of vessels. It must be 

 obvious that no simple rule of a given number of inches 

 per foot of depth of hold, can now be applied with equal 

 fairness to all vessels alike. Each requires to be judged 

 of separately, and to have its special characteristics 

 adequately appreciated. The problem of framing a gene- 

 ral scheme for regulating the freeboards of the principal 

 types of ships involves, firstly, the consideration of how 

 freeboards should vary in vessels belonging to any given 

 type, according to size, proportions, and form ; and, 

 secondly, the consideration of how the freeboards of 

 vessels of similar sizes, proportions, and forms, but of 

 different types, should be regulated relatively to each 

 other." 



He went on to show how the elements of size and relative 

 proportions are dealt with in the Committee's tables, and 

 also how form is taken into consideration by means of 

 approximate coefficients of fineness. 



The effects of differences in sheer and round of beam 

 are separately investigated, and also the influence of 

 deck-erections — such as forecastles, poops, midship 

 houses, and others — upon seaworthiness. The whole 

 question of allowances for deck-erections of various kinds 

 is one which cannot be brought within the scope of exact 

 different treatment ; and it is a point upon which the 

 Committee appear to have been guided more by the 

 opinions of seamen and by the recorded experience of 

 successful ship-owners than by any other considerations. 

 Among the chief scientific questions connected with 

 the safe loading of ships are those of structural strength 

 Vol. XXXIII.— No. 843 



and stability. Prof. Elgar describes as follows the 

 manner in which these have been treated by the Load-line 

 Committee : — 



" Flush-decked steamers of the 100 A class in Lloyd's 

 Register, which are of full strength to the upper deck, 

 are, it is known, amply strong enough to bear loading to 

 the freeboards given in the tables. Spar and awnmg 

 deck-vessels, which are of less strength, may become un- 

 seaworthy through excessive straining action at sea if 

 loaded to the same depths as the vessels above-named. 

 And there are instances of vessels of those types having 

 been severely strained at sea, and of some which have 

 probably foundered in consequence, when loaded unduly 

 deep. The principle which the Committee has adopted 

 in dealing with these and other vessels that are inferior 

 in strength to those of the 100 A class of full scantling 

 ships in Lloyd's Register, is tcr fix approximately the 

 hmits at which the stress upon the material of the hull 

 shall not exceed that of the stronger class of the same 

 proportions, form, and moulded depth, when loaded to 

 the freeboard required by the tables. In our present 

 state of knowledge of how to calculate exactly the relative 

 stresses upon the materials of ship's hulls, it is impossible 

 to rely upon absolute accuracy of comparison, but the 

 principle is a sound one. It can be applied with a fair 

 degree of accuracy in many cases, and it is only to be 

 expected that the present deficiencies in this branch of 

 science will be made good in time. In thus adopting 

 Lloyd's 100 A class as a standard of strength, the Com- 

 mittee must not be supposed to indorse Lloyd's Rules in 

 any sense. They are merely taken by the Committee as 

 being the best, or, indeed, the only recognised standard 

 we now have. 



" The question of stability is one that has often been 

 raised in connection with the regulation of freeboards. 

 Stability is, however, so intimately associated with stowage 

 that it is only possible to deal with it by defining how ships 

 of various proportions and types are to be stowed. The 

 Load-line Committee did not feel called upon to deal with 

 an independent problem of such magnitude and such great 

 complexity as this. Stability need not ordinarily enter 

 into the determination of the load-line, except for the 

 purpose of insuring to ships of great proportionate depth 

 the necessary stability at sea ivhen employed in the carriage 

 of grain, or other cargoes that are approximately homo- 

 o-eneous. If properly qualified persons are intrusted with 

 the assignment of load-lines, they will readily distinguish 

 between vessels in which stability is likely to be a question 

 of importance and those in which it is not. In cases 

 where vessels will obviously admit of being loaded so as 

 to become unstable at sea, the owners should be looked to 

 for particulars of the stability, and for furnishing proof 

 that, so far as stability is concerned, the vessel may be 

 safely laden with her intended cargoes to the ioad-line 

 given in the tables, or to such a reduced draught as may 

 be considered proper. The responsibility of providing 

 stability, or of showing that sufficient is provided, must 

 be left with ship-owners. Stability is regulated by stowage ; 

 and no mere provision of freeboard, height of platform, or 

 strength of structure, can make a ship safe if her stabihty 

 is not secured by .proper stowage. The regulation of 

 stowage has but little more to do with freeboard tables 

 than has the regulation of steam-power, bulkhead division. 



