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maintain the same sailing dates as the new vessels. Fortunately the SLAMAT. was origin- ally designed to burn coal, though the punker spaces were suitable for carry- ing oil, and before entering service the vessel was fitted to burn oil so that the boilers were of ample capacity for a greater engine output. In convert- ing the Sramat, it was therefore pos- sible, as far as boiler capacity was concerned, to increase the turbine horsepower output by about 25 per cent by. alterations to the turbines alone. It was found that this increase in pro- pelling power increased the speed of the vessel about one knot without al- teration of the vessel’s lines. The ad- ditional one and one-half knot needed was gained by altering the ship’s form and the design of the propellers. Conversion of Dutch Ship Careful investigation by the ship- yard engineers indicated that it was possible to attain the required speed of 17% knots by the following altera- tions: 1. Lengthening the fore body by 15 feet on the waterline and at the same time applying the Maier ship form to the fore body. 2. Improving the effective power by applying propellers of improved Wi:- ton design. 3. Substituting a streamline rudder. 4. Shortening the bilge keels by re- moving the portions most seriously in- terfering with streamline action. 5. Altering the shaft bossings to give minimum resistance. In tank trials, of models of the orig- inal vessel and after the proposed al- terations enumerated above, the re- sults showed that for a speed of 17% knots before conversion, 12,900 shaft horsepower would be required, while for the converted ship only 8100 shaft horsepower would be required. These results were confirmed during the maiden voyage of the ship ater con- version by accurate speed and horse- power measurements carried out on the trip from Rotterdam to Marseilles. The owners of the Stamar reported that before conversion this vessel con- sumed 4220 tons of oil on a round voy: age between Rotterdam and the Dutch East Indies at an average speed of 15 knots, and that after conversion on a similar round voyage, at an average speed of about 17% knots she con- sumed only 4270 tons of oil. Accomplished in Three Months An interesting feature of the con- version was the speed with which the work was carried out. The time avail- able, without undue interference with the service, was only three months. Within this period the forward part of the vessel to a length of about 98 feet was removed and a new part, including frames and double bottom, having a length of about 124 feet was built on. The new materials, plates and sections, required for the conversion, weighed 30 about 420 tons. Great care was used in planning the work to expedite com- pletion. Measurements were taken be- fore the ship left for her last voyage before conversion, and a new fore body plan was laid off from these measure- ments. Material was ordered, shaped and worked from mold loft information and the new fore body constructed. When the ship arrived at the yard, practically all of the material was worked and ready for immediate use after the removal of the original fore body. By these time-saving methods the vessel occupied the floating dry- dock for a period of only eight weeks in order to undergo this elaborate con- version work without necessitating night work of importance. Wilton’s Engineering & Slipway Co. in further preparation for helping the shipowner solve the problem of what to do with his 10 or 12 year old obso- lescent ships secured the license for ap- plying the Lentz principal and other associated features for improving the performance of reciprocating engined Scotch boilered vessels. This license was secured in 1929. In 1930 the Wil- ton shipyard modified the machinery installation of the S. S. OormarsuM, and the S. S. Spar. The same company also similarly converted the MHILVER- sum, the Oostzer and Stotwouk. All of these vessels are fitted with reciprocat- ing engines and savings in fuel con- sumption of more than 30 per cent have been obtained. Sea Trials Before and After It is interesting to note that prior to the alteration of a vessel a trial trip is held, of at least six hours’ duration in loaded condition at sea, during which the fuel consumption is checked and all other necessary data is record- ed. After alteration, or as this partic- ular type of conversion is termed “Lentzifying’, a second sea trial is held under similar conditions. Dock trials may also be held before and after conversion under precisely sim- ilar conditions when the engine is kept running for at least six hours continuously while developing its nor- mal power at the rated revolutions, Contracts for this type of conver- sion usually contain a clause stipulat- ing that for every per cent of saving below the guaranteed figure the con- tractor is to pay the owner a penalty of approximately 10 per cent of the contract price. On the other hand the: owner must pay the contractor a pre- mium of equal value for every per cent by which the actual saving exceeds the guarantee. What Modernization Means Briefly this process of alteration or “Lentzifying”, the name applied be- cause one of the features is the substi- tution of a Lentz poppet valve cylinder for the ordinary high pressure cylinder of the usual reciprocating engine, is mainly as follows: 1. Fitting of superheater elements in the boiler tubes, increasing the steam MARINE REvieEw—June, 1932 temperature to about 570 degrees Fahr, at the stop valve. 2. Substituting a Lentz poppet valve cylinder for the usual high pressure cylinder. 3. Fitting of a special feed water heater of the Lindholmen-Motala type. This heater is of a new contraflow principle and of several stages. The design is simple. Each stage consists of a seamless tube internally provided with tubes through which the feed water passes. Exhaust steam from aux- iliaries and if necessary also steam from the middle and low pressure re- ceiver is used for heating purposes. With a low steam consumption tem- peratures of over 250 degrees Fahr. are easily obtained. 4. Alterations to boilers, furnace gear and funnel. The object is to increase the velocity of the combustion gases and to bring about closer contact between these gases and the surfaces surrounded by water. The combustion gases are com- pelled to cover a longer distance and hence a more intensive transmission of heat is possible. 5. Fitting of a special kind of oil separator for the feed water. The use of superheated steam makes necessary an effective feed water fil- ter. This special filter which is pat- ented by the Deutsche Werft makes the condensate entering the water space strike against a plate by which the whirls existing in the water are eliminated. The water space is sub- divided into two parts by a slanting guide plate. 6. Improved lubrication of the en- gine. Although this feature is not directly a part of the improvements included in the term “Lentzifying”, the lubrica- tion of the engine may be improved by using the patented system.of Henry Brillie, engineer in chief of the Com- pagnie Generale Transatlantique. In this system the bearings and thrust blocks are provided with oil grooves of a special profile, so shaped that the streamline of the oil film receives a whirl-free flow-off. Experiments with these oil grooves prove that the effi- ciency of the engine can be improved by the adoption of this system. Several other minor modifications which depend upon the arrangement and design of the particular machinery installation under consideration, are also applied. The entire engine is carefully examined in connection with the use of superheated steam. If not already done the middle pressure slide valve is balanced and the high pres- sure and middle pressure stuffing boxes are provided with metallic pack- ing. If necessary the condensing plant should be examined and tested to ob- tain a maximum vacuum; also con- sideration should be given to the wis- dom of working the auxiliaries with low superheated steam. Special steam dryers are fitted and boilers are ot course provided with soot blowers.