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THE NEW YORK PUBLIC LIBRARY 897127
ASTOR, LENOX AND TILDEN FOUNDATIONS R 1920
PRINTED BY PEWTRESS & Co.,
Steam Printing Works, 28, LITTLE QUEEN STREET, LINCOLN'S INN FIELDS, W.C.
VOLUME LIII.-N0. I.
JANUARY, 188 4.
THE STABILITY OF MERCHANT SHIPS.
QURING the last year the attention of those interested
in shipping has been drawn in a marked degree to the question of the stability of merchant ships. In
July last, in the launching of a vessel on the Clyde, a great disaster occurred which was made the subject of a searching investigation conducted by an eminent naval architect, and in September an enquiry was held by the Wreck Commissioner into a case of partial capsize and sinking in harbour of one of the largest merchant steamers afloat. The Daphne enquiry served to bring home to shipbuilders the importance of attention to precautions which had of late somewhat fallen into disuse, and was made the occasion of probably the first public statement in scientific language of a branch of the theory of the stability of floating bodies. The second enquiry certainly did not bring out anything new, and indeed there appeared no reason arising from the merits of the question why any great amount of consideration should have been given to the question of the ship's stability ; but nevertheless the Austral like the Daphne was made to illustrate a lesson on the importance of scientific knowledge and
enquiry, and the Wreck Commissioner vied with the most distinguished naval architect of the day in enforcing the value and necessity of a more scientific treatment of the question of the stability of merchant ships in the future, than has obtained in the past.
The question of the stability of ships of war has received very much more attention than that of merchant ships, and while it may be said that this has been rendered the more necessary on account of the rapid succession of novel types of war ship, it is at the same time more practicable in consequence of the greater certainty of the conditions involved. Merchant ships do not differ from each other so much as war ships do ; changes in design in the former are made by slow and easy steps, and thus any advance in the wrong direction is the more likely to be corrected by experience before it has gone very far. On the other hand the problem of the stability of a merchant ship is indefinite, whereas in the war ship it is well defined. The latter has her weights disposed at the will of her designer and although changes are caused by consumption of coal, or may be brought about in action by the perforation of compartments and admission of water to them, such changes can be accurately estimated and provision made to meet their consequences. In a merchant ship, on the other hand, varying weights are a very large part of the account, and their disposition is beyond the control not merely of the designer, but even of the owners or master. The stevedore proceeds upon simple methods, the result of his own experience, and their successful application in each case depends upon his individual knowledge and judgment. The mate has his time fully occupied while the vessel is loading in keeping tally of the cargo, or in receiving and checking the amount of stores, and the master of the ship too often is anywhere but on board the ship supervising the stowage of the cargo. Meanwhile merchant ships are multiplying, new types are coming into existence and old types are being transformed, the result being that vessels of most diverse forms, proportions, and qualities exist, in which rule of thumb stowage is to say the least very much less certain to secure good results than if the work to be done were of a more uniform character. No wonder then
that the question is constantly arising as to whether science can be applied to meet the new condition of things. Individual experience if it be strictly applicable is always the most valuable ; but may not science, which is merely general experience systematised, be useful where on account of the variety of conditions no one experience is sufficiently extensive to serve the purpose. The question then arises—Can anything be done to make science available practically in the loading and management of merchant ships as regards their stability ?
The Daphne disaster had in itself very little connection with the general question of the stability of merchant ships, nor do the special conditions which led to that vessel's deficient stability at the time of launching necessarily point to any defect in her seagoing qualities. A similar accident happened to another vessel on the Clyde a short time ago, but in that case the mishap stopped short of disaster. The Hammonia which, just after being launched, went over to a considerable angle and did not recover herself, proved, when her curve of stability was got out, to be subject to as rapid a loss of righting power as the Daphne ; but while being so deficient in stability at launching draught that in this condition her maximum righting moment is at 33° and her stability vanishes altogether at 53°, it appears that calculations as to her condition at load draught have proved that she is a vessel with sufficient stability. Sir Edward Reed's conclusion, as regards the Daphne accident is that in respect of instability of vessels at launching draught there is a danger which has not been appreciated in the past, and has not been made the subject of scientific investigation. Vessels at ordinary loaded draughts are comparatively safe with small initial stability, because when inclined they gain stability so rapidly, and hence it has been usually considered to be safe to launch ships with a small metacentric height, and one of the witnesses on the enquiry did not hesitate to say that before the experience furnished by the Hammonia and Daphne accidents it would have been considered safe “ to launch with any positive stability at all.” .
While it may be quite true that no scientific treatment of this particular question has been made public before the Daphne enquiry, it is, we think, quite another thing to say that its practical bearings