STRUCTURAL STEEL STANDARDIZED CARGO VESSELS. 107 



be mathematically developed. Such plates and shapes were developed full size on the 

 mold-loft floor, reproduced on template paper, having all rivet holes punched in them 

 on proper gauge lines and for a matter of record carefully measured up and detailed 

 to dimension on individual drawings. Even with complete drawings it was difficult 

 for the fabricating shops to reproduce the plates on account of the edges and gauge 

 lines being curved. These lines could only be located by dimensioning a series of 

 points on the curves. 



As we could not count upon two men springing a batten and getting the same 

 shape between points, we overcame this phase of the problem by sending templates 

 of the shell plates in the molded sections to the fabricating companies. These tem- 

 plates, made on template paper approximately 1/32 inch thick, were direct copies of 

 the original template developed on the mold-loft floor'. A difficulty was experienced in 

 the shrinkage and expansion of these templates and, to insure the change of shape 

 of the templates causing no misfits, each template was marked before being sent out 

 with certain dimensions. To begin with, the paper used is fairly heavy fabroid ma- 

 terial, which has a rather low coefficient of expansion. It was then marked and cut 

 in accordance with the development on the scrive board, and rivet holes, etc., were 

 laid out upon the paper, spaced and dimensioned with great accuracy. 



The correct dimension for the length of the template, also the correct dimension 

 for width at each end, was painted on with arrows indicating exactly where these di- 

 mensions were taken. In addition to this, a straight line was scratched the full length 

 of the template approximately at the center line. The shop receiving this template 

 was requested, in all cases before using it, to measure it and make certain that the 

 template, as they used it, was correct to the check dimensions given. They were also 

 requested to test the straight line scratched on the template with a straight edge. 

 When, as was very frequently the case, they found that the dimensions did not 

 check or that the line was not straight, they were required to bring it to shape either 

 by dampening it or drying it as the case might be. There still remained, of course, 

 the possibility that when a template had been expanded by dampening and stretch- 

 ing, the expansion might have taken place all at one section of the plate rather than 

 throughout its length. As it was possible for this to happen, neither checking the di- 

 mensions on the template nor checking the straight line would detect the error. To 

 overcome this we insisted that the fabricator check their templates against the de- 

 tailed drawings which were furnished them. Inasmuch as the local steel tapes 

 determined the measure of this variation, it was of prime importance that every 

 tape at each and all of the outside works should be uniform. 



A single tape was selected for the Newark Bay shipyard where the original 

 templates and drawings were laid down on the mold-loft floor, and with this master 

 tape every other tape to be used was compared and carefully calibrated, and a co- 

 efficient, plus or minus, prescribed in each case. In this way it has been entirely prac- 

 ticable to insure dimensional agreement not only within the different departments of 

 the Newark Bay shipyard, but similarly within the different departments of every 

 outlying contributive establishment. 



