76 • AN ANALYSIS OF THE ISHERWOOD SYSTEM 



to an average greater height of 12 feet for the transversely framed vessel than would 

 be necessary for the Isherwood ship, a difference of 12,000 foot-tons. That this mat- 

 ter did not receive attention in the comments of shipbuilders is probably due to the 

 circumstance that the power costs are customarily charged to overhead and not to 

 the ship directly, thus obscuring this part of the information. 



CONCLUSION. 



While the particular ship here used for purposes of analysis and comparison is 

 not above criticism, it should be evident from the above that the Isherwood system 

 of longitudinal framing offers many and important advantages, while the disadvan- 

 tages seem to be relatively slight. Whether further development in shipbuilding 

 will be along the lines of longitudinal or transverse framing, or a compromise be- 

 tween the two, is a question that the future alone can answer. 



DISCUSSION. 



The President : — ^The paper which has just been presented to you, "An Analysis of 

 the Isherwood System of Ship Construction," is now open for discussion. 



Mr. F. M. Hiatt, Member: — Mr. Flodin, in his opening paragraph, implied that the . 

 engineering profession engaged in the art of shipbuilding has l>een perhaps ukra-conservative. 



The problem before the naval architect, however, is not to demonstrate his own daring 

 hut to design ships which will enlist the financial support of the investing public. I recently 

 asked a banker to state for me those qualities of any paper which are most essential to insure 

 its successful flotation. His answer was : — "There is only one such quality and that is the 

 security of the invested principal." 



The bridge designer can demonstrate the efficacy of his design, including such innova- 

 tions as he may desire to embody therein, by a test load upon the completed structure. The 

 naval architect, however, cannot at will produce a standard wave for the test of his wares. 

 He must depend upon the test of time. Until that test is passed, the burden of proof is placed 

 upon the designer, not by his conservative colleagues but by the investing public. Nor can 

 this requirement of the investor be unduly criticized. It may be remembered that financially 

 the Great Eastern instanced in the paper was a failure. 



It seems to me that the claim of superior longitudinal strength of ships framed on the 

 Isherwood system has not yet been demionstrated. Section moduli and computed stresses 

 in ship work are of value only as a means of comparison. If the premises upon which we 

 base the calculations are not similar, the comparison fails. 



In computing the section moduli of ships framed on the transverse system, we are accus- 

 tomed to neglect intercostal longitudinals. If, however, the longitudinal framing of an 

 Isherwood ship be neglected because it is intercostal between bulkheads, we penalize that 



