CONCRETE SHIPS

Dominion, Volume 10, Issue 3155, 6 August 1917, Page 7

CONCRETE SHIPS

"SPEED IN CONSTRUCTION" AUSTRALIAN'S PROPOSAL Under the auspices of the Engineering Association of New South Wales an ad-_ dress upon ferro-concrete • 'shipbuilding' was last week delivered by Mr. J. <J. M'Ewin at the Eoyal Society's room's. Subsequently a discussion took place upon the proposal. "An opportunity has now presented itself to us to make a useful contribution to tho Allied cause," said Mr. M'Ewin, by way of introduction. "It is that of providing new ships to replace vessels now being destroyed by tho submarine campaign of the Central Powers. Such ships must be delivered quickly; they, must be constructed in considerably numbers, and they must be sufficiently capacious and speedy to lie useful, and reasonably safe from pursuit from underwater craft. This address is,.to urge that the required vessels should be built of, reinforced concrete; and, in bringing the matter forward, I would point out that the project is not nearly so revolutionary as the original proposal for the substitution of iron for wooden ships last century. Numbers of small craft have been built already of tho proposed material in various parts of the worjd, from motor boats to steam tugs, and .from cargo punts and caissons to pontoons. No large vessels have yet been instructed on this method, but concrete steel engineering has now become an exact science, and there has been ample experiment work carried out to ;iid in the solution of the problems that may arise in the construction of the proposed ships. "The ' construction of large c< ncrete vessels in the past has naturally not appealed to the practical commercial shipbuilder. He would regard such a work as an experiment, which, even if a successful one, might not catch the fancy of conservative ! shipowners; and the large amount of capital that would be absorbed by the cost of the forms or moulds would .greatly augment the first cost of a single concrete ship. At the present moment, however, wo are faced with a unique proposition—the rapid construction of a largo fleet of standardised vessels, exact counterparts of each other. All of these could and would be moulded from the original set of forms required, and tho ultimate cost of these moulds' per ton constructed would become a negligible quantity. As this item.has naturally been a serious stumbling block in the way of this class of construction the consideration of the whole scheme may be approached in the- present instance with confidence. The materials required for the concrete steel construction could all bo produced in Australia. The skeleton of the vessels will jequire steel bars, which Lithgow, Newcastle, and other producing centres should be able to furnish in amplo quantity; and steel wire, which we 6houlu be able to draw locally if supplies from abioad are unobtainable. So much for the skeleton. The remaining materials required are cement and aggregate. The highest grade of cement is obtainable in great abundance, and the best' of materials for making up the aggregate is'inexhaustible in positions convenient to the coast.

"A vessel of concrete' steel properly designed should bo but little heavier than a wooden vessel of the same strength. Its maintenance cost will bo very low.It will resist, corrosion and will offer no attraction to those-marine insects that are t'he ruin of wooden vessels. It will resist decay indefinitely, and in (ho evem. of any damage resulting to the hull uiay be quickly and satisfactorily repaired at very email expense. A. reinforced concrete vessel can be designed of equal strength to a steel ship. The proposed vessels will find their most useful service in the carriage of wheat in bulk. The tank ship style of construction, therefore, may fce followed with advantage. The longitudinal and transverse diaphragms will permit of a strong and light type of vessel. It will be verv safe for the transport of wheat in bulk, as no shifting of the cargo could take place, and the rupture of any one tank from a torpedo or other cause would not endanger the ship. 1 .would suggest 'that these vessels should have a carrying capacity of MOO lons. Their dimensions would then be approximately: Length 27Sft., beam +ll't., depth 21ft., draught ISft.. engines IWIO horse-power, speed IO.V knots. In the absence of plate for boilermaking purposes, if seems inevitable that ||„,;o vessels should be fitted with Diesel r-ni'ines. preferably of the two-stroke cycle type. With' a little effort these could be made in-this country."