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March, 1919 somewhat resembles a shell plate joint at a frame. The additional welded work neces- sary where a: tapered liner is fitted in order that the bulkhead angle may pass fairly from one strake. of shell plating to the other is shown in Fig. 6. Similar work is shown in Paget oF where the bulkhead angle passes from one strake of bulkhead plating to another. While in these cases there is considerable difficult welding, such work is less likely to give trouble by leakage than ordinary riveted ana caulked liners and joints. In_ this illustration it may be noted that in the connection of the bulkhead ‘to the shell the boundary bar is fastened by rivets with nonwatertight spacing, a continuous weld being worked along the kcel and intermittent welds at the toes of the bar at the bulkhead and shell plating. This is an inter- esting comparison with American Continuous Weld around Bulkhead Flats Boviidary Angle Continous Weld FIG. 10—RAISED AND SUNKEN SYSTEM AND CONTINUOUS WELDS—THIS ILLUSTRATION SHOWS THE METHOD USED IN WELDING BULKHEADS TO THE SHELL PLATING ideas in regard to right-angle connec- tions. Incidentally, it may be added that the ordinary frames are riveted to the shell. The Raised and Sunken System The remaining illustrations show similar work on the’ second plated on the raised and sunken sys- tem. In Fig. 3 it is shown that in addition to this difference, the bulk- head boundary bar has a continuous weld at the toe, both at the shell and the bulkhead. This work was done for comparison, but it is hoped that experience on service will show such extra work unnecessary. Fig. 8 shows the riveted edges and butts. There is a continuous weld on the outside and inside of the laps, whereas in the other ship, shown in Fig. 4, there was an_ intermittent weld: on the inside. Further, on ac- count of the strake being a raised one, the liner extends the whole width in- stead of tapering, so that additional welding is involved. Fig. 9 shows the welding at a lap of bulkhead plating, and is similar to the work on the clinker system ship, ship, Hlustrated «= im: detail “som 2 Bigs 55. Fig. 10 shows the bulkhead bound- ary bar, with its three continuous welds instead of one continuous weld at the heel and two intermittent welds at the toes, as shown in Fig. 7. Fig. 11 shows the considerable weld- ing where the boundary bar passes over the lap of the bulkhead plating and a raised strake of shell plating, necessitating two sets of liners. Summary of Results Obtained The following interesting experience has been obtained from this work: In the case of the clinker system, where there was no overhead work on the outside of the ship, the plating was practically watertight on the first test; but in the other ship, on water- testing, the laps which had _ been overhead-welded on the outside leaked, and difficulty was experienced in over- coming the leaks. In the case of slight leaks being discovered under test in compartments which have been caulked in the usual manner, the de- fects can generally be made good while the water remains in the com- partment. In the case of welded work, however, it has been found that the presence of water makes welding practically impossible; so that, to remedy leaks by welding, it is neces- sary to empty the compartment. In the ship on the raised and sunken system the tests occupied a_ longer time than usual, and it is therefore proposed that with future welded work the tests preliminary to a final water test should be applied by air pressure. This would probably en- able leaks to be detected. On summing up, American and British practice differ in the follow- ing interesting points: American shipbuilders favor spot welding for bracket and such-like con- nections, while British shipyards pre- fer riveting. For right-angle watertight connec- tions the American practice tends to heavy welding, the British to riveteu angles, the rivets being widely spaced and backed up by lighter welding, or to notch angles with light intermittent welding. For butts, notched or riveted straps with widely spaced rivets and one run of heavy welding at the joint are preferred by the British instead of a strap lightly arc-welded to the plates with heavy welding at the joint, which appears. the. present tendency in America. For plate edge joints, British prac- tice favors a riveted lap with widely space: rivets, while the American practice is to dispense with riveting entirely. Finally, experience in Great Britain shows that at present arc. welding 2 THE MARINE REVIEW 131 should not be applied to mild steel plates of greater thickness than 25 pounds, nor can it yet be used on galvanized or high tensile steel; but the writer has heard of no such limits being imposed in this country. Marine Railway Supplants Drydock (Concluded from Page 122) at 9 p. m. the hauling winch. com- menced to pull on the cradle. As almost the entire weight of the vessel was still water-borne, the initial inertia was small and was easily over- come. The cradle moved forward up the ways with the vessel gradually settling down until entirely supported. During this operation great care had to be exercised in manipulating the mooring cables at the stern, which was subsequently found to have set- Continous Weld ror LENQI/ OF Lifer COlITIIIVOUS We/d aroulrd Bulkhead qpereda Lier Boting Continous Weld Boundary Arg/e Continuous Weld Continuous Weld for Lengrh OF Liner FIG. 11—RAISED AND SUNKEN SYSTEM AND CONTINUOUS WELDS—THIS ILLUSTRATION SHOWS THE METHOD OF WELDING BULKHEADS IN THE WAKE OF THE LINERS tled within a few inches of the cen- ter of the blocks. The cradle steadily mounted the ways with its huge burden until the entire hull became visible. The total distance of 275 feet was covered in 40 minutes at a mean speed of ap- proximately 7 feet per minute, and the vessel was high and dry in posi- tion adjacent to the shops all ready for reconstruction work. The alterations and reconstruction called for increasing the molded depth by 8 feet, remodeling the stern, new bottom for half the length. of the vessel, construction of cargo holds, masts, booms, deck winches and all fittings necessary for relaunching com- pletely ready for sea. Within 75 days of taking possession of the site, the necessary machine shops, carpenter shops, mold __ loft, stores, offices, etc., had been installed and the vessel brought out of the water. The operations were carried out under the direction of D. A. Andrus, the company’s manager and engineer at Quebec. EA SRN aS ag Pe ee LE RR LOM ONSE say May bre, Lae | ae eee ee ae hegre crew quarters, etc., providing: FES ae COR ee ta] ae ee ape tre SR ah al a arcs 8 * Seis tert: