A MODERN CARGO BOAT.

Star (Christchurch), Issue 11027, 16 March 1914, Page 8

A MODERN CARGO BOAT.

ARRIVAL OF THE CAIRNROSS. : ' PROPELLED BY GEARED TURBINES. Dining I lie past ten years thoro has been ,i dended change in the machindiv for the propulsion of steamers and tho intiodu(tion of tho turbine marked a new era in shipbuilding. In New Zealand waters tho only vessels fitted with the turbino arc the Union Company's Maheno, Maori and Wahine, and as regards the two ferry steamers the results obtained have been eminently satisfactory. In tho case of tho Maheno it is said tho results have not been so good, and experts state that this is due to the fact that high-speed turbines driving small propellers are unsuitablo for long vessels of medium speed on long voyages. It has been recognised that tho best results are obtained when a vessel is capable of maintaining an average speed of about sixteen knots, which runs out at anything between 1500 and 2000 revolutions per minute. As. far as tho cargo steamer-was concerned it was anticipated that her low speed would always make her class be contented with engines of tho reciprocating typo, but the time has now arrived when the tramp steamer, as far as propulsion power is concerned, will have an engine-room as up-to-date as her passenger rival. The problem of utilising the turbine engine in cargo and other steamers of moderate speeds was one that was subjected to careful consideration, and after numerous experiments tho question was ultimately solved by the engineers fitting the steamer Vespasian with • geared turbines, an experiment which proved successful. As far as New Zealand is concerned tho geared turbino was unknown in ships, and it Avas not until the arrival in these waters a week ago of tho New

Zealand Shipping Company's chartered steamer' Cairnross from Montreal that

he engineering fraternity and the pub-

lic had an opportunity of-becoming acquainted with tho new type of propulsion power. Yesterday tho Cairnross arrived in Lyttelton, and naturally .much interest will bo centred in her during the next day or so. As far as tho vessel is concerned she

is practically a new ship, having been launched only' twelve months ago by Messrs AV. Douxford and Sons, Sunderland, for the Cairn Line of Steamships,' of Newcastle-on-Tyne. She is 369 ft Din in leugth, o7ft in breadth and 27ft 9in

moulded depth, with a dead-weight capacity of 7830 tons. At present the Cairnross and tho ATcspasian are the only cargo vessels afloat with, the new system of propulsion, although a third vessel is building on the Clyde, and in

tho course of a-few months tho Union Company's Maheno will be refitted at Port Chalmers with the new gear. The Huddart-Parker Company have also given an order for a vessel fitted with the geared turbine. Tho Cairnross in appearance is not unlike the usual stylo of tramp steamer, but as far as the engines are concerned she is vastly different.... There, is no cumbersome machinery;hero and: there, and all that is observable to the. visitor are small horizontal'cylin-ders-containing turbines. The latter, two in number, are of the high speed type, capable.of running -about 1700 revolutions per minute for ahead driving. The high-pressure turbine is fit-ted-on "the starboard side and a lowpressure-- on the port side;, fitted in series, an astern turbine being embodied in the same casing as the latter, •fust abaft of tho turbines is the gearbox containing the bulky mechanism

that has made the geared turbino a success. Although tho turbines run at a speed of 1700 revolutions per minute tho machinery is so arranged that the propellflig shaft which drives the- solitary large screw can be geared down to 65 revolutions per minute, even although the engines are going at top speed. Tho turbines of the Cairnross are of the Parsons typo, and are about 2000 shaft horse power, while the pinions which transmit the power of tho turbines to tho propeller shaft aro about six inches in diameter. In rough weather the strain on tho shafting is eased somewhat by flexible coup-

lmgs. . . / When the Cflirnross was launched another vessel of "the same dimensions, the Oairngowan. was tested in tho English Channel for the purposes of comparison. Tho Cairngowan had a single screw and was driven by triple expansion reciprocating engine.?, the boiler power being identical. Both vessels wore supplied with tho same coal and the weather conditions were not of tho best. As the outcome of the test the results proved in favour of tho gear-turbincd Cairnross, with .an economy in 'fuel of fifteen per cent. Subsequently the two "vessels loaded coal for India under identical conditions and it was shown that the Cairnross maintained an average speed of 10J knots and saved about five tons of fuel per day as compared with the Cairngowan. It is estimated that on voyages of about 170 days the anuual saving in fuel would be well in the vicinitv of £ISOO.

The Cairnross has a large quantity of agricultural machinery and motor cars to land and will also load homeward cargo. She is expected to leave Lyttelton on Wednesday.