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September, 1909 "TAE. Marine Revicw SHOWING PROPELLER OF BARKENTINE ALEMBIE. motor coasters. They are not motor coasters to be run anyhow, and all the time under power. On the contrary, order to obtain the full economy the power ought only to be used where the canvas is sufficiently ineffective as to delay the vessel or in saving towage in or out of port. The economy of a vessel designed to depend mainly on her motor is necessarily a totally ditfer- ent affair. Auxiliary Motor Barques. It is also interesting to note that amongst British ship owners there is some movement towards equipping the larger kind of sailing vessels with aux- iliary motive power. The sailing ship is to have another lease of life, and it must be remembered that there are hundreds of fine iron and steel ships afloat--vessels which in earlier days paid good dividends. What is to become of them? Admittedly they are unprofitable to work in the present day against the modern steamship. The most advanced pioneer of the auxiliary motor move- ment as applied to sailing vessels among British owners is the Clyde-built ship Modwena, but though her tonnage is only 500, and therefore a good bid short of the register of the average wind- jammer of trade, she represents a suf- ficient advance on the immediately pre- ceding record of dimensions to justify 'the hope that auxiliary motor power may ultimately save the sailing ship from extinction. The notable feature of the design is that she is an ocean-go- ing sailing vessel primarily, her crew is practically that of a ship, and the source of her auxiliary power takes up very little room. The Gardner paraffine en- gine installed on the Modwena is of a special six-cylinder type, which was de- signed for some Russian submarine boats. The diameter of the cylinders is 11. ih. by 10-in. stroke, and on. the test bench the motor developed 200 horsepower at 450 revolutions per min- ute. The Gaines reversible and feather- ing propeller is two-bladed, and enables the propeller to be masked by the stern post so that there is no drag when sail- ing. The diameter of the propeller is 54 in. This is the largest reversible and feathering propeller so far installed. The fuel is paraffine, and the speed of the boat on her auxiliary power is 9% knots. Judged by the figures above given the installation is almost ideally economic. No doubt 200 horsepower is beyond the power which many trading vessels of the same dimensions could carry with a certainty of earning money. The Modwena, too, is much bigger than the average coaster to whose case ma- 303 rine motor makers are diligently apply- ing themselves just now. Still, through the figures relating to the Modwena, the coasting owner may learn a great deal. The fact that a Gardner engine of this type and power costs probably $10,000 may possibly stall off many inquiries right away. It is, however, the bearing of her success on the problem of the ocean-going auxiliary sailing ship that makes the Modwena the interest- ing vessel she is. In her engine in- stallation two new problems had to be solved, and it is in respect of these that justifies the hope there is regard- ing the future of the auxiliary motor power for ocean-going sailing vessels. One was how to cool the exhaust, and the other how to provide for the fresh water drip to the snifter air valves. Curiously enough the makers found a solution of both problems in one. The exhaust is led through two pipes fore and aft of the motor into two cooling cylinders, 15 in. in diameter and 3 ft. high. Seacocks below the water line admit sea water to these cylinders, most of which immediately evaporates on contact with the exhaust. The mix- ture of the exhaust gases and steam then rises through a series of baffle plates in the upper part of the cylin- ders, all the salt being deposited on the baffles, which are removable through gas-tight doors. Most of the exhaust, thoroughly cooled, passes out through the usual vent pipe, while the heavier steam passes into a condensing cylinder set between the evaporators, whence it is pumped up as fresh water to the wa- ter drips. While these are important advances, it is not to be assumed hastily that there & Ce 56 H. P. Kromuout Om ENcINE,