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material through the punch, and about as many if not more hours labor would have been required. An espe- cially good job of course is obtained by drilling. It is undoubtedly true that drilling would not be as economi- eal as punching in other kinds of work, and where multiple punches are available, but the fact remains that the drilling was done as cheaply as the punching could have been done in this instance, and it is food for thought in future channel construction work. After fabrication, the channels were lowered through the hatch and were bolted and riveted up in two sections on the tank top of the vessel. The dock crane then lifted the two sec- tions, comprising the bulkhead, into place. The bulkhead bounding angles were then put on, the bulkhead rivet- ed up in place, and the bracing set up. Under this méthod, the use of the crane was only required for a small fraction of the time necessary with plate construction where every plate has to be hoisted in place. _ The only countersinking required was in the side and bottom bounding angle bars. The channel flanges were riveted together with an _ ordinary pneumatic hammer. If a compression or bull riveting machine had _ been available, about 75 per cent of the bolting up could have been eliminated, but as the bulkheads were non-water- tight and the key bolts were quickly set up, the method proved satisfactory. Though this is the first actual ap- plication of channel construction to - lake freighters, plans have been pre- pared for tank tops and side tanks. To the right on this page there is shown a cross section of a_ stand- ard Great Lakes bulk freighter, with a length of 604 feet, a beam of 60 feet and a molded depth of 32 feet, and having the side tanks and tank top, laid out for a patented channel steel system of construction, which has been approved by the American Bureau of Shipping. An analysis of the strength of the channel side tanks and tank top, and the present plate construction in the above mentioned ship has been made, and it shows that the permissible load per square foot for the channel con- struction is 3100 pounds per square foot while for the present plate con- struction the safe load per square foot is 2100 pounds. The permissible load of the plate side tank is about 600 pounds per square foot and that of the channel about 700 pounds per square foot. oP Or 988s VINE Sess “O-, Sar osmces ee ee TTT Water-tight Floor Construction — | Forex Ast — Spaced 720° Alternative Method of 20" Q0UBLING PLATE, \—— Brackets rer vp ard riveted, offer tert tep (3'/v place. Angle bor ur Hanged piole of varying . Wdths riveted To ernts of channels 2 G1 5f"s 11.7 * Angle headers aie avd cavlhed. é. <—— Athrert Shps S) 4p shear in side flanks Tank Fp i010 0.0 040 0 90 30.9 "Ship Channels; Butts strapped Under: side Jark Tepe Channels Ofter Sectiavs are riveted together; Age : Web but fstraps to come over Moors B, er Geo 0 8ly*, 2 94's 72. SP 60 oo e200 ee : ae ave pike: bs Lo _9_al a \ Dy ad 7 ° Diagram vf ‘tating (S* Bracket plate Tole /*- /-O° § é 2 8 é 3 & g A — efor fA ; - 6% Ib U7" Angie header efectrically G i - y> es All measurements taken from center of keelson and worked ovtboard. Allow .03° overrun per sear 5 Ole 13° A. chi en oi plawgoe sak gf? -- = Sf's at all high and intermediate floers. 7 05h 4 13° L Clips ip tor paper , D —~ Sie Tark Bulkheot Detail fre f= [SPT OY didi ta tae ' 1 Veale ("= 1-0" ” 4°P itch — fore # APH ——__—> Seam rivers S g 5 S S ~ iy ~ Ww G = = x SG fe Bottom Longitudinal Charneks S S 2 ay S = oS Q e Ss ~ x = RS by Q ty Angle bar 5°15 +162" Angle or 20" Flanged plofe for sach seam. (sex Bracke? Connection design) \ Tank or Mopper of (2° 25% Wrvctural Channels. allow 03" overrun Brechat LYd7a han NW1E/+VOa fremesr The channel tank top is therefore approximately 50 per cent stronger than the present plate tank top, and 12 2E Ar pees 32 MARINE REVIEW—June, 1927