270 



NATURE 



[July 2 2, iSb'o 



THE RUSSIAN IMPERIAL YACHT, 

 "LIVADIA" 



IT is not surprising that the character of the great 

 steam-yacht Livadia, just launched upon the Clyde 

 for the service of the Emperor of Russia, is exciting wide- 

 spread interest. Since Noah built the Ark, no floating 

 and moving structure has been constructed in such direct 

 contrast as this vessel with all that has gone before it. 

 Every other ship afloat has, in its chief features, been a 

 development of the ships that preceded it, not excepting 

 even the circular ironclads of Russia, for they were not 

 the first circular vessels that had been designed and con- 

 structed, and although they had some steaming preten- 

 eions, these were too moderate to challenge seriously 

 either the principles or the practice of naval architects. 

 In the new yacht of Admiral Popoft's design, however, 

 ive have a steamship that, by its very existence, challenges 

 the fundamental piinciples upon which fast passenger 

 steamers are constructed by all the rest of the world. 



We give herewith illustrations, of which the firft (Fig. i) 

 is an external view of the IJvadia as seen out of water ; 

 it is taken from a model which was constructed under the 

 care of Admiral Pupoff, and shows at a glance the general 

 form of the ship. Another (Fig. 2) is a cross section, 

 irhovving among other things the transverse distribution of 

 the boilers and machinery. The third (Fig. 3) is a plan 

 showing the horizontal distribution of the same, and indi- 

 cating more clearly than the other the positions of the 

 three propelling screws.' It is obvious that such a form 

 of vessel, propelled in the manner exhibited, suggests 

 many questions of scientific interest ; but most of these 

 will be best discussed after the steam trials of the vessel j 

 have taken place. For the present it will be sufficient 

 to take notice of the general characteristics and qualities | 

 v,hich she presents to view. 



It is desirable at the outset for the reader to observe 

 that the Livadia consists of a shallow hull 235 feet long, 

 153 broad, and drawing, when supporting all its burdens, 

 but 6| feet of water. From a foot or two above the water's 

 surface arch upwards and inwards with considerable 

 curvature until they each meet (at about one-sixth of the 

 whole breadth of the ship from the side amidships) the 

 fore and aft sides of a naval palace, which extends from 

 stem to stern. Although the width of the ship at the 

 water-line is 153 feet, her width at a few feet above the 

 water-line is therefore much less — about no feet, we 

 believe. In smooth water, therefore, the resistance to 

 onward motion will be those encountered by a vessel 153 

 feet broad and 235 feet long ; but when the ship gets into 

 heavy seas they will be free to pass over her low sides, 

 and the ship that will have to divide and encounter them 

 will be 1 10 feet by 225. As the object of this vessel is to 

 furnish ample accommodation for the Emperor and his 

 suite at sea, it may be fairly presumed that the width of 

 the superstructure has been kept greatly within that of the 

 hull proper, and the accommodation thus restricted, for 

 the purpose of materially improving the behaviour of the 

 vessel at sea. The arrangement will doubtless contribute 

 greatly both to the speed and to the steadiness of the 

 ship in great waves, its value for diminishing rolling 

 having already been demonstrated in the circular iron- 

 clads, which have superstructures of less width than the 

 ship, and which are remarkably steady even in seas that 

 roll freely along the decks of the hulls proper. 



The primary and chief fact concerning the anticipated 

 steadiness of this exceedingly short, broad, and shallow 

 ship, is that it is to be secured by means the very opposite 

 of those which have lately obtained in this country, viz., 

 by aid of enormous stability. Since the general accept- 

 ance of Mr. Froude's theory of rolling, the aim of the 

 naval architect has been to send his ship to sea with 

 sufficient stability for safety, and with no more than is 



" We are indebted for the 

 the editors of Eii^inccring ; 



I specially i. 



ample for that purpose ; because steadiness at sea is, 

 under the modern theory, promoted by keeping the 

 stability or righting force as small as possible, within the 

 limit just named. The metacentric height, which is from 

 12 to 15 feet in the American monitors, which have great 

 proportionate breadth of water-line, has been restricted to 

 6, 5, 4, and even less than 4 feet in many of our large war 

 ships ; indeed the Sultan, which is one of the steadiest of 

 our large ironclads, has a metacentric height of only 2i 

 feet, while the Inconstimt's, the steadiest of our un- 

 armoured ships, is but very slightly in excess of this. 

 This reduction of .metacentric height increases propor- 

 tionately the "period of oscillation," and makes vessels 

 reluctant to accept the disturbances which waves en- 

 deavour to impose upon them. But while the tendency 

 of modern science has thus been to diminish metacentric 

 height and stability, the effect of the Livadia' s form and 

 proportions will be to give her enormous metacentric 

 height and stability, the object in both cases being 

 identical, viz., improved steadiness in waves. Nor is this 

 course pursued, strange as it may seem to some, and 

 violently antagonistic as it is to modem practice, without 

 the sanction of science. For while a ship with very small 

 stability, and consequently very long natural period of 

 oscillation, is ordinarily secured against rolling by her 

 slowness to accept the wave impulses, the ship with very 

 large stability, and consequent very short period ' of 

 oscillation, is ordinarily secured against excessive rolling 

 by the very readiness w'ith which she accepts those 

 impulses and conforms to the mean movements of the 

 waves. It is true that in the latter case the exemption 

 from rolling motions is not so great as in the former, 

 because a certain considerable amount of rolling is un- 

 doubtedly and necessarily involved in this conformity to 

 wave motions ; but this amount of rolling is very much 

 less than that to which a ship is exposed which has 

 neither stability so small as to render her comparatively 

 indifferent to wave-pressures, nor stability so large as to 

 force her to keep her decks approximately parallel to the 

 wave-surface. Ships with intermediate degrees of sta.- 

 bility are li;ible to roll much and to accumulate large rolling 

 motions, especially when subjected to successive impulses 

 from similar waves, whereas the ship of enormous sta- 

 bility, while always obeying each wave, is by that very 

 means exempted from the tendency to accumulate the 

 effects of a succession of waves. In all this reasoning — ■ 

 the generality and meagreness of which we fully recognise 

 — it is of course assumed that the waves in question are 

 of sufficient magnitude in proportion to the size of the 

 ship to stand in individual relation to her. The immense 

 breadth of the Livadia will doubtless preserve her from 

 being rolled by small waves, including under that desig- 

 nation waves which would cause many ordinary ships to 

 roll with violence. As regards longitudinal rolling, which 

 is usually called pitching, if we neglect the onward 

 motion of the'ship, and consider the matter from the same 

 point of view as that just adopted in speaking of trans- 

 verse rolling, we may say with confidence that the longi- 

 tudinal stability of the Livadia will be in excess of the 

 transverse, and that no excessive pitching need be feared. 

 Owing to the shortness and light draught of the vessel, 

 she would probably (if not advancing) tend to accompany 

 pretty closely the motions of the wave-surface when 

 heading to waves of sufficient size to cause her to pitch- 

 As her length is so small (less than half that of several 

 transatlantic steamships now at sea), the vertical motions 

 of the bow and stern will of course be correspondingly 

 small for given angles of pitching. 



It is when we come to consider the case of her enor- 

 mous steam power being applied to force her ahead 

 through large waves that we experience some difficulty in 

 predicting her behaviour. For we here touch upon a 

 question which has been but very imperfectly investi- 

 gated ; we might even say, has scarcely been more than 



