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142 Charles Buchanan Charles Buchanan, for whom the of- fice of principal of chief ship survey- or's staff was created, is one of the best known naval architects THE MARINE REVIEW ties of the ship, that the rolling and pitching in a seaway were reduced and the speed increased. There was a gain in the deadweight capacity of an amount equal to the corrugations. The April, 1914 vessel of similar dimensions and draught, the vessel designed on the Isherwood system was shown to have an increased deadweight capacity of 200 tons, or 2% per cent of the dead- weight capacity of the or- of the day, and created a very favorable impression in ship building circles in the United States during the visit to this country three or four years ago. He has been associated with mer- cantile ship building since his young manhood. Prior to joining the service of Lloyds Register in 1880, he was chief draftsman for A. McMillan & Sons. Later, he enjoyed a varied experience in a number of the ship- "building ports. Since 1891 he has been stationed in London, holding for the last seven years the position of assistant to the chief ship surveyor. For many years past he has been associated particularly with the duty of dealing with plans of vessels submitted for the commit- tee's approval and this work has made him an authority in the latest development of shipbuilding practice throughout the world. He is a member of the depart- mental committee on bulk- head atid watertight com- partments in ships. Modern Cargo Ships Striking details of recent changes in the construction of cargo vessels were given before the Insti- tute of Shipbrokers, London, on March 18, by J. W. Isherwood. Sir Walter Runciman presided. Mr. Isherwood at the outset sug- gested caution in extending the grow- ing practice of 'building vessels with- out longitudinal bracing. He remarked that the recent disaster to the Okla- homa, which was a ship actually pos- sessing side stringers, pointed to the risks to which stringerless ships were exposed. A stringerless ship was con- venient, inasmuch as there were no shelves for the lodgment of grain and coal, and the cost of construction was less, but it would appear that the plating was more: vulnerable to dam- age between the frames, and the whole 'ship exposed to greater injury from broaching on collision. The corrugated-sided vessel had from all accounts proved a successful type for small cargo ships. It was claimed that the corrugations had the effect of improving the steering quali- dinary vessel, and a longitu- dinal strength 15 per cent in excess of that built on the ordinary transverse system. Detailed comparisons showed the Isherwood ships to be stronger in every detail. "Generally speaking," add- ed Mr. Isherwood, "the floor of the vessel is carried out flat to the side of the ship instead of peaking the bilge brackets, as was the prac- tice in vessels of ordinary construction. The flat floor gave an increase in. cubic capacity and the absence of beam knees an increase in the capacity for bale goods." In vessels employed exclu- sively for the timber trade the loss in capacity. could be overcome by building ves- sels broader or longer than | usual. In one actual' in- stance where an order was given for a'timber ship of 16,500 tons deadweight with the same internal capacity for long timber as the trans- versely built ship, it was found that an increase on the original dimensions of 15 ft. in length gave an in- crease in deadweight of 900 MR. CHARLES BUCHANAN method of construction had not been adopted in cargo vessels of large size or of high speed, so that it could not be stated whether proportionate econo. mies would be maintained. The Ayre-Ballard or arch principle of construction consisted of a trans- verse arch over and above the normal hull and forming an integral part. ot the same. The arches enabled pillars to be dispensed with, thus giving a comparatively clear hold. The type would appear to be mainly suitable for single-deck vessels, but "upto" the present time steamers of large size had not been constructed according to the arch 'principle. Several interesting comparisons were made by Mr, Isherwood of ships of certain styles constructed in the or- dinary way and on the Isherwood principle of longitudinal framing. Com- paring a single-deck. cargo vessel hav- ing the dimensions of 399 ft. by SE te molded by 28 ft. 314 in. molded, a deadweight carrying capacity of 8,000 tons, and a draught of 24 ft., with a tons, with the use of 200 tons less steel than would be required in an ordinary vessel of smaller dimensions. Any objection that the Isherwood longitu- dinals formed shelves for coal: and grain might be met by the fact that these longitudinals in a vessel of 8,000 tons deadweight would only accom- modate four tons. This could be easily swept off, as the longitudinals themselves formed ladders up the sides of the ship. The Isherwood construction was better suited for ventilation and ren- dered the hull practically free from vibration. It also permitted of ex- peditious cleaning, and opened up the possibility of successfully increasing the length of a given vessel while still retaining the same breadth and width. In conclusion Mr. Isherwood point- ed out that during the period of the oil ship boom no fewer than 99 ships. of this character, of 528,- 000 gross tons and approximately 792,000 tons deadweight capacity, had been contracted for. The increase in