The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

Diesel Electric Canaler Tynemount Editor Marine Review: Sir:--In various articles which have recently been published in THe Marine ReE- VIEW, in which reference has been made to the Diesel-electric propelled canal vessel Tynemount, less than justice has been done to our share in the design of this vessel and it occurs tO ws that it might be of interest to your readers if we place on record' the. process of evolution in the Cana- dian canal type which underlies the building of the Tynemount and in which we can certainly lay claim to have taken a leading part. Any in- terested reader of your columns knows what has been done by us in recent: years. to improve» the' -dead- weight and increase the all-round ef- ficiency of the Canadian canal type. Absolutely held to fixed hull dimen- sions by the canal locks, we have yet been able, by careful adjustment of hull scantlings and improvement of the propelling machinery, to add 15 per cent to the greatest deadweight thought feasible a few years ago and to reduce the fuel consumed in this class of vessel from about 10 tons average per day throughout the sea- son of navigation to between six or seven. Five or six years ago our at- tention was directed in this connection to the possibilities of the internal combustion engine, offering great re- duction in engine weight, considerable saving of valuable hold space, and economy in fuel, cost and weight. Careful investigation of the existing types proved, however, that no di- rect drive by internal combustion en- gines, gas or oil, could offer any hope of reasonable propulsive efficiency or reliability. Influence of Local Conditions Theorists on this subject are too apt to neglect the influence of local conditions and nowhere are these con- ditions more likely to make their in- fluence felt than in the Canadian ca- nal trade. So important are these peculiar local conditions and so great is their influence on thé propulsion of .the Canadian canal vessel that it is no exaggeration to say that in de- signing a propeller for that type, the least important consideration is to get the best go-ahead speed out of the vessel. More care is dévoted to get- ting a good maneuvering wheel, one that will get the vessel quickly into-- and even more important--quickly Ont ofa 'lock, and that. will. control and handle the vessel at all speeds in the canal system with facility and cer- tainty. Everyone familiar with this canal trade, and trade on the lakes gen- erally, knows what is meant by the term "a lake wheel," and knows what happens 'when any other type of pro- peller is experimented with. In an ordinary steamer type of Canadian canaler with dimensions, say, 250 ft. by 42 ft. 6 in. by 14 ft. draught, co- efficient say; 0:63 or over, and: 700 I; H. P., the normal propeller would be 12 it, diaimeter: by 12 ft. pitch, with laree blade area and 'square blade tips. Revolutions not exceeding 80 per ninute. Such a' propeller could not be swung by any internal com- bustion.engine of 7/00 H,. P. yet in- wentéed: . Electric Transmission At the time we first approached this subject, the Diesel engine avail- able for marine use was in small units, 200 H. P. and thereby. Larger sizes were under construction but could not be relied upon for com- mercial purposes. It occurred to us that by using an electric transmission system we could divide the total pro- pelling power into handy units by cutting out one or other of the units, telate the power generated to the ex- act requirements of the vessel at any given moment and materially improve the consumption conditions in that way. We realized that it was always important in oil engine work to have regard to the necessity for the lowést possible consumption if saving were to be effected over the corre- sponding steamer's bill for coal, which any can be obtained at a very low rate all over the lakes. This subdivision of the power into particularly attractive in canal work because in the canals sub-units was the speed is limited to four miles requiring less than 200 H. P.; in the lake and river reaches 400 H. P. is quite sufficient; while in open water and against the river currents 600 H. P. is necessary. Therefore, our first designs show three units of 200 H. P. each, all furnishing current to a single screw of the ordinary lake type and turning at 80 revolutions per minute. It must be evident that by the in- troduction of the third element, elec- trical transmission, it is possible to leave the Diesel engine in its most ef- ficient high speed four-cycle form and yet to retain all the undoubted ad- vantages of the single slow speed full bladed steamer wheel. On the other hand, to avoid the introduction of transmission of any kind, much time and ingenuity have been unhappily devoted to altering the propeller to suit the new motor and the new motor to suit the old propeller with the usual result--a compromise un- satisfactory to all concerned. Furth- ermore, no such compromise, how- ever successful, could get over the serious drawback of having to re- verse the main engines, a perfectly impossible proposition when it is un- derstood that ani «traversing "the -St. Lawrence and Welland canal systems over forty locks, often close together in series, have to be negotiated. Works like a Charm Everyone knows that the reversing gear as now fitted on the Diesel en- gine works "like a charm with com- pressed air behind it; but to back and fill with the best of Diesel marine engines a couple of hundred times in a few hours, it is necessary either to run the engine with compressed air, a very expensive game, or to ruin the engine and gear in very short order. There is no escaping from the con- clusion that a transmission system of some kind is necessary to reconcile the conflicting revolutions of the new engine and the old propeller and to relieve the engine of the complica- tions and troubles incidental to rap- idly alternating, reversing, stopping,