144 DATA ON HOG AND SAG OF MERCHANT VESSELS. 



was to measure the deflection under different conditions of load, then make the customary 

 strength calculations, knowing the lines and the character of the loads, and see how they 

 actually tallied with the computed deflections. 



Before starting the work it seemed that there might be a question of temperature affect- 

 ing the problem, especially as our attention had been drawn to that fact by an earlier paper, 

 which called attention to the noticeable change in form, due to variations in temperature, 

 in torpedo boats. It was decided to investigate that first. The manner in which the inves- 

 tigation was carried out was to take the vessel afloat, and to take continuous readings of 

 deflection throughout the day, measuring the temperature of the water, the temperature of the 

 deck, and measuring the deflections, in much the same manner as indicated by Mr. Corn- 

 brooks. 



The boat on which we made these experiments was the Atlantic, and her dimensions 

 were 388 feet between perpendiculars, beams 54 feet 4 inches, and mean draught 24 feet. 

 She had a depth of 31 feet 3 inches. The general character of the boat you are perhaps 

 familiar with. I will make a crude sketch of it here on the blackboard. 



g^ »8 «7 #6 *s #4 *3 »3 *2 «i Transit 



^. tzr— -rrrr— izj — -j 



T3 



rzr 



Sketch showing Line of Sight + Stations. 



The machinery was aft (indicating on blackboard), having a large open space for cargo 

 throughout the central part of the vessel; we had a transit set up on the forecastle and 

 sighted to eight stations down through the entire hull structure. The transit was guarded 

 to make sure we could recover our original position, and deflections were noted in this way. 



Experiments were made on two days and they were started very early in the morning. 

 The work was in conjimction with some thesis work of Messrs. Bortner, Gordon and Ram- 

 sey, who carried out the actual observations. They arrived shortly after three o'clock in 

 the morning and took continuous observations for deflection throughout the entire day, at 

 about half-hour intervals. The temperature of the water and temperature of the deck were 

 obtained by means of small thermometers plastered on the deck and hung into the water 

 alongside. I do not think we are interested in any other part than the maximum deflection, 

 which occurred shortly aft of midships. 



If you will permit me to make this brief table, it will clearly show what occurred. 



