THE BARREL SHIP.

Auckland Star, Volume LXIV, Issue 88, 15 April 1933, Page 6 (Supplement)

THE BARREL SHIP.

USE OF STREAM L!N ING.

SCIENTIFIC ECONOMIES.

THE ISHERWOOD DESIGN. When We think of fast ships We think of engines and of thousands of horsepower. We are apt to lose sight of the fact that the modern ocean liner owes her high speed as much to improvements that have been jnade in hull designing as in power plants. Moreover, improved hull lilies have contributed materially to the overall economy of the present-day cargo vessel, not to mention the advantages obtained by the use of streamlined reaction rudders and other eddy-reducing and wake-Straightening devices, says a Writer in the "New York Times." In the light of what has been accomplished by both German and British naval architects the announcement that Sir Joseph Isherwood has developed an "arch-form" or barrel design for ships which will enable them to carry 25 per cent more Cargo for the same displacement, reduce the fuel bill by 30 per cent and make 40 knots possible is to be taken very seriously. Moreover, Sir Joseph is not the man to make rash statements. His invention of the Isherwood system of longitudinal construction for ships has made him a world-famous figure. Increased Cargo Carrying. Sir Joseph has not [been alone in urging a scientific study of hull forms in order to secure higher efficiency. Streamline rudders, fins on the rudder posts of stern frames, bulbous bows and finely modelled sterns all point to the growing realisation that the time has come for vessels to slip through the water with less resistance. Most of these reforms apply only to fast passengers liners. The slow freighter and the eight-day passenger transatlantic ; passenger carrier have hardly been affected. Yet these are the real money-makers of the sea. The improvements have all been in the direction of increasing the cargo-carrying space. Sir Joseph applied his new barrel form to the forward and aft ends of an 8500ton vessel which had given a satisfactory account of itself. With the addition of only 180 tons of displacement, secured •by only three inches deeper immersion, he proved his contention. A second vessel improved by adding some 220 tons displacement showed that scarcely more power was required over a range of 9 to 12 knots than before. Even better results would have been c attained with special propellers and rudders. The efficiency of tramps built according to his principles is such that they can be made to steam at 9 knots in sprvice on a daily coal consumption of less tban 12 tons. At present Sir Joseph is carrying out tests to determine the proper barrel shape of a 35-knot liner.' The Perfect Streamline. The sum and substance of streamlining is this: It is easier to part water or air with a single-correctly designed bulk than with a*knife-like bow and a fat stern. Nature made the discovery eons ago, but it took man thousands of years to see it. Her fast fish are blunt-nosed and her fast birds are blunt-breasted. Correct curvature is the secret of streamlining and therefore speed. If the curvature is correct the bow-wave and the foaming wake, dearly beloved of artist 3, are reduced. They -would disappear altogether if it were possible to build a theoretically perfect hull and drive it in theoretically calm weather in a theoretically glassy sea. Probably the perfect streamlined hull must be a dream forever. There will always be eddies and' wakes, because a vessel must not ship heavy seas and beshe must stand terrific strains as she rolls and pitches. Sir Joseph Isherwood's new form would ibe regarded even by him as a compromise despite the lower engine power for a given speed and its greater cargo < v apa>aty.