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\ Tae Marine REVIEW February, 1919 Prince Rupert, oF THE GRAND TruNK PaciFic RaILway. painting being white enamel. The main staircase of the ship will be a notable feature, the panelling of the walls being in white enamel and the balustrades of wrought iron elegantly designed. The promenade on the shade and boat decks will be _ spacious. On the shade deck forward of the funnels is the observation room, panelled in maple and sycamore. This room will be specially lofty and well lighted by very large square 'windows, allowing passengers to have Submersible HE submersible 'Thrasher,' build- ing at Cramp's shipyard in Phil- adelphia, is the first reproduction in this country of the Laurenti type of under- water craft which have given so much satisfaction in the Italian navy and else- where in Europe. On this account, we have reason to be interested in the recent performances of two other Laurenti submersibles recently added to the navies of two Scandinavian countries. The records of these ves- sels can be taken as a fair index of what may be expected of the Thrasher. The Hvalen, built for Sweden, is a boat of only 230-tons submerged dis- placement, and in cruising trim has a reserve of buoyancy of about 60 per cent of 'her surface displacement. She has a shipshaped form of hull--in con- tradistinction to the cigar-like body ot the submarine, and, in conjunction with her great reserve of buoyancy, embodies those prime essentials where- an uninterrupted view of the scenery en route. The cabins in all the deck- houses will have wide rectangular sliding windows provided with jalousie screens. The Prince Rupert .will tbe provided with a wireless telegraph in- stallation, refrigerating machinery for ship's stores and dairy produce, elec- tric light and steam heating through- out. The rudder is of the balanced type wholly below the waterline and will be actuated by a telemotor steer- ing gear. Boat Hyalen in the submersible differs from the submarine according to the definition of Monsieur Laubeuf, the French originator of the submersible. The Hvalen has made 15.2 knots on the surface, and submerged has an endur- ance of three hours at a speed of 7 nautical miles. Unlike any other type of under-water craft, these Laurenti boats are driven by triple screws, and this arrangement affords a very desir- able flexibility of motive power com- bined with economy. Aboard, surface speed is deemed more important than a corresponding increase of submerged speed; and, associated with seaworthiness, is the means by which the submersible can cover rapidly considerable distances between their bases and the field of their offensive usefulness. High speed submerged is obtained only by sur- rendering a large measure of surface mobility; and the gain in submerged speed is not commensurate with the sacrifices made. The under-water boat, to-day, is a sort of submarine ambush, and her effectiveness when once submerged is limited largely to awaiting an enemy's approch within. her own zone of hidden activity. She is strictly speaking a moveable torpedo battery, and her duties are in no sense to be confused with the purely aggressive service expected of the high-speed surface torpedo-boat. A submersible capable of making 15 knots an hour is a craft which may operate far to seaward and over wide areas in conjunction with the armored fleet, and in this way can serve the double purpose of a dirigible mine field or the stricter defensive function of harbor protection. In this greater adaptability the submersible shows the advance over the submarine. Our own coastal conditions demand submersi- bles rather than submarines, and ves- sels of this sort will be still more valuable when naval protection is re- quired for the Panama canal. One of the conditions under which the Hvalen was built prescribed that the vessel should be able to run under her own power, unescorted, from Spezia to Stockholm--a total distance of quite 3,500 knots. The longest single run was from Spezia to Carta- gena, a distance of 790 miles; and this was accomplished in 72 hours--the boat using only her central screw. During the Hvalen's long trip she en- countered a good deal of stormy weather, and yet her commanding officer has spoken in terms of the highest praise of the manner in which the little vessel went steadily on