THE OTAKI TRIAL.

Evening Post, Volume LXXVI, Issue 142, 15 December 1908, Page 3

THE OTAKI TRIAL.

AN INTERESTING VESSEL. RECIPROCATING TURBINE ENGINES. (From Our Own Correspondent.) LONDON, 6th Novembor. The steamer Otaki, built by Messrs. William Denny and Brothers, Dumbarton, for the New Zealand Shipping Company, has just completed her trials on the Clyde. The owners' official trial took place on Monday when a speedof 15.09 knots was registered. The handing over trials took place yesterday The Otaki is the first merchant vessel fitted with the combination of reciprocating and turbine machinery, the only previous case being the destroyer Velox. In that case, for cruising purposes, reciprocating engines were fittod at the forward end of the turbines, and were connected up whon low speed was desired, but in the case of the Otaki the attempt has been made to obtain greater efficiency by addifig a turbine with separate screw to the usual rociprocating engine equipmont. It has been generally recognised that for oareo vessels or vessels of moderate speed such as the Otaki, it is commercially impracticable to havo a complete outfit of turbines, and the arrangement in the Otaki has boon designed to overcome this difficulty. _ The vessel is fitted with two sets of reciprocating ongin.es, driving twin screws fitted in the ordinary fashion, but between these two engines is fitted a low pressure turbine of vory large size. Tho steam, after, having done its work in the reciprocating engines, instead of entering the condenser directly, is passed through the low-pressure turbine which drives v. centre screw. • The turbine revolves only in one direction, the turbine screw being used for propulsion solely when tho vessel is going ahead, ohango valves aro fitted so that the steam may be either passed directly into the condenser, or to tho low pressure turbines, hence in manoeuvring the vessel becomes an ordinary twin-screw, the centre screw taking no part. The twin-screw engines are triple expanKion of the ordinary design, having- cyfindbrs 24iin, 39in, and 58in by 39in stroke. Tho Otaki is virtually a sister ship to the Orari, which was built and delivered in 1906 to the same company, and when Messrs. Denny were consulted about the building of another vessel they suggested to the owners the desirableness of making an experiment with the combined engines. Tho owners, characteristically up to date, agreed to the experiment, tho only stipulation being that the builders should give a reasonable guarantee as to efficiency, and that tho capacity of the vessel should not be reduced. Tho boiler installation was to bo precisely fhe same as in the Orari. The lengtfi was therefore slightly incroased in the Otaki to make up for tho loss due to the three tunnels as against two in the Orari, and the stern post waa so arranged that the third screw could be fitted iiy an aperture. The dimensions of the Otaki are: 464 ft 6in x 60ft x 34ft. The builders' trials took place on Saturday, and both the reciprocating engines and the turbines ran with the greatest smoothness. On the completion of the trials it was found that the average mean speed 'of the Otaki was 15.02 knots while the average speed of the Orari, under similar conditions, was 14.6. The builders express themselves as satisfied with the result and anticipate that the improved efficiency shown on trial will be maintained during tho sea-work of the vessel. As this vessel's trade is between this country and New Zealand, a voyage of practically 13,000 miles each way, there will be an excellent opportunity of proving the advantages of this system.