Would She Be Crushed by the Sea? 



How the Navy finds out if submarines may 

 be submerged with safety to great depths 



Bv Robert G. Skerrett 



IT has recently been said that many of 

 Germany's submarines have been car- 

 ried to the bottom by reason of in- 

 herent weaknesses — structural faults, in 

 brief. This means that the hastily built 

 U-boats have sprung a leak and foundered 

 simply because the defects were not dis- 

 covered before sending the craft out upon 

 active service. 



The Italians shrewdly anticipated the 

 results of wartime pressure in turning out 

 in haste a large number of under-water 

 torpedo boats; and Major Cesare Lau- 

 renti cleverly designed a testing dock 

 which would make it possible to subject a 

 submarine to the physical stresses of sub- 

 mergence at any practicable depth without 

 risking the boat the while in deep water. 

 That is to say, the submersible could be 

 tested in harbor, right at the building 

 yard, where her constructors could make 

 sure that she was absolutely sound in hull. 

 The United States Navy also uses the 

 Laurenti dock to determine thp fitness of 

 its submarines for sea. 



How can this be done ? The hulls of these 

 vessels must be sturdy enough and tight 

 enough to withstand the searching pressure 

 of the sea -iOO feet down below the surace. 

 Laurenti's novel dock consists mainly of a 

 long steel tube which is capable of resisting 

 a pressure from 

 within corre- 

 sponding to a 

 crushing force 

 at any prescrib- 

 ed submergence; 

 only the dock 

 always remains 

 at the surface. 

 One end of this 

 tube is perma- 

 nently sealed, 

 and the other 

 can be closed by 

 a great, gloi)ular 

 caisson or gate. 

 By swinging when the submarine 



this gate aside, {jreat globular door 



when the dock is in proper condition, a 

 submarine can be floated into the tube, 

 settled upon keel blocks and otherwise 

 held from shifting when the gate is sealed. 

 The cylinder is completely filled with 

 water. The submarine is then subjected 

 to external pressure just as she would be 

 if lowered deep into the sea. But there 

 is this difference; her crew are inside of 

 her and stationed where they can watch 

 for leaks and observe certain instruments 

 that show how much the hull yields to 

 the exterior water pressure, and whether 

 or not the structure returns to its original 

 lines when this pressure is relieved. The 

 testing pressure is gradually raised by 

 means of powerful pumps on the dock. 

 They try to force more water into the 

 already filled cylinder, and thus the sub- 

 marine is subjected to a crushing force 

 which can be raised to correspond with 

 that at any assumed depth. 



During the test, the observers in the 

 submarine are in telephonic communica- 

 tion with the people in charge of the 

 pumping plant, and should anything go 

 wrong or a grave leak develop, the pres- 

 sure can be lowered instantly and the 

 great tube drained in a few minutes. 

 Thus, while imitating the conditions of a 

 deep submergence there are none of the 



dangers that 

 might be met 

 if the boat were 

 out at sea. 



In the last 

 few years, un- 

 der- water 

 tori)edo boats 

 have bern modi- 

 fied in order to 

 meet changing 

 military needs. 

 The Laurenti 

 dock makes it 

 possible to try 

 them out be- 

 is well inside, the ^O^e gomg into 



is tightly closed actual servlce. 



.S4'2 



