METHOD OF CONSTRUCTION OF CONCRETE SHIPS. 



INSIDE FORMS. 



With one exception all the contractors prefabricated the inside forms in sections 

 ready to set into position without requiring any carpenter work to be done within 

 the hull. The lines for the inside forms were obtained from the mold loft floor or 

 from templets taken from the floor. These forms had to be constructed with great 

 exactness, for in many cases there was only ^-inch clearance from the steel on all 

 sides. To show the accuracy with which such forms can be made, it is of interest 

 to know that in the case of one ship none of these prefabricated forms had to be 

 removed for adjustment after being set in place. 



There perhaps is no phase of the concrete ship construction work which is 

 more complicated than the construction of the inside forms. A description of the 

 exact method followed at one of the yards in obtaining the shape and dimensions of 

 the various sections will be of interest. 



The frame drawings gave the thickness of the shell and the depth and width 

 of the frame, as in Fig. 30, Plate 9. The problem was to obtain the width of the 

 frame forms A''^ W, and the panel form P, and also their relations to the mold loft 

 line which passes through the point ML in Fig. 30 (c). The bevels across the 

 frames at the critical places were first obtained. These critical places were at the 

 bottom of the bilge L, top of the bilge U, and at the main deck. The method of ob- 

 taining the bevels was to measure the distance a in Fig. 30 (a) between half frames 

 on the mold loft. This divided by the frame interval 51 inches gave the bevel across 

 that particular frame between the two half frames. These bevels were taken in a 

 plane perpendicular to the shell. 



The next step was to obtain the dimensions A, B, and C of Fig. 30 (c) which 

 were all functions of the frame bevels. As a great number of these had to be com- 

 puted, graphical charts were made for convenience. 



It will be noticed in Fig. 30 (c) that the diagonal distance A is given to the 

 outside line of the shiplap form produced. This was done in order that a right- 

 angled, beveled chamfer strip could be used at the intersection of the frame form 

 and panel form as shown. The panel forms were so cut that their edges were in 

 the same plane as the side of the frame. 



Following is the form in which the information was given the mold loft car- 

 penter : — 



As the mold loft lines were straight, i. e., not the conventional ship curves, 

 forms for the sides N and W could be made up to approximate size beforehand. 

 These would be brought in to the floor in pairs and laid down adjacent to the frame 



