152 CHANGE OF SHAPE OF RECENT COLLIERS. 



be the maximum permissible. It is, perhaps, generally known that the lake freighters have 

 draught marks amidships as well as at each end. I think any information of that kind would 

 be valuable, as to the maximutn, amount which has been observed in any case and its effect 

 on the ship. 



Mr. Smith : — We had a very serious case during the last season, where the ship, when 

 loaded, had the same draught aft and midships, and drew a foot less forward, and it had 

 quite a destructive effect on the hull of the ship and loosened up a great many rivets. 

 Usually, we do not calculate to get more than two or three inches sag in the middle. 



Mr. Francis T. Bowles, Past President:— I would suggest that the practical value of 

 this paper would be much enhanced if either the author or Mr. Tawresey would add to their 

 remarks an exact description of the most accurate method of laying off the draught marks 

 on a vessel, and of correcting it when the vessel is loaded. I am aware that there are some 

 tricks in both of these businesses. (Laughter.) 



Naval Constructor T. G. Roberts, Member (Communicated) : — I am glad the author 

 of this paper has introduced the curves showing conditions on the Nereus, which were pre- 

 pared under my direction at Newport News. I may also add that similar curves were previ- 

 ously prepared by me in the case of the collier Proteus, the results of which were quite similar 

 to those shown for the Nereus. The Proteus being the first of these two vessels to be com- 

 pleted, I prepared these curves without any knowledge that similar data were being, or 

 had been, taken in the case of the Sparrows Point colliers ; and the purpose I had in view 

 was to be able to account for an anticipated difference between the weights taken of the dif- 

 ferent parts prior to incorporation into the vessel, and the displacement as determined from 

 the draught marks at completion. It struck me that the condition of bending actually found 

 would be reasonable to expect, which the subsequent observations confirmed. I forget now 

 how much the displacement was affected by the observed difference between the loaded con- 

 dition under sag and the designed condition with keel flat as in dock, but I think it was some- 

 thing like 180 tons. Anyhow, it was an appreciable difference to account for when the 

 weights and the displacement are being compared, or when the conditions at the trials are 

 being met. Since the contract for the vessels required the work to be according to the best 

 merchant practice, there was no provision for expenses to the Newport News Shipbuilding 

 and Dry Dock Company and to Mr. William Gatewood for volunteering to supply the nec- 

 essary facilities to enable this work to be conducted by the force of my office. 



Admiral Richard M. Watt, Vice-President: — Merely as a matter of interest, I would 

 ask attention to an experience of my own many years ago, when I was assistant to Admiral 

 Bowles, at the Navy Yard, New York. He assigned me the task of hauling out seven tor- 

 pedo-boats. They were small in size, and the longest, as I remember, was 160 feet. The 

 vessels were hauled out on improvised ways, and I noted with some consternation on arriving 

 at the yard one morning that the shores set up on the previous afternoon under the over- 

 hang forward on several of the vessels had dropped out during the night. This was very 

 alarming, but, of course, the only thing to which this could be ascribed was temperature 

 changes. 



