124 SUBMARINE SIGNALING AND A PROPOSED 



ing article by Captain Armistead Rust, U. S. N., on the subject of "Safety at 

 Sea." He proposed in effect steamer lanes which must be adhered to in fogs, extra 

 slow speed where such lanes cross, and a code signal of six letters or numbers to in- 

 dicate latitude, longitude, course and speed. 



There is no doubt that a close adherence to steamer lanes in fogs would re- 

 duce the chances of collision. 



None of the above systems would, however, be sufficient in the opinion of the 

 author to meet satisfactorily the urgent demand for safety and fill the requirements 

 of the practical mariner. 



The ideal conditions would be met if the elements necessary in handling the 

 vessel when both are clearly visible were equally available in a fog. The following 

 proposed method is submitted as a solution of the problem. 



Before proceeding to its description, although perhaps scarcely necessary, it 

 may make the system clearer to briefly review the customary method of handling 

 two vessels in sight of each other as prescribed by the "Rules of the Road." 



The officer of the watch while still distant takes a bearing of the other vessel, 

 and observes closely whether the bearing changes. If the bearing does not change 

 the vessels would arrive at the point of crossing at the same instant and collision 

 would occur. If the bearing changes the vessel hauling ahead will arrive at the 

 crossing first and the other hauling aft will pass astern. 



In this case the element of relative bearing is known accurately, and the dis- 

 tance is not accurately known, but must be ample to permit of successive bearings 

 being taken with sea room remaining to maneuver if necessary. An experienced 

 seaman is usually able to estimate the latter. 



A satisfactory system of fog navigation would require: — 



(a) The presence of another vessel to be ascertained at least as far as the 

 steamer lights are visible, namely, 5 miles. 



(b) A knowledge of the course and speed of the other vessel. 



(c) Information as to whether or not the bearing of the other vessel is chang- 

 ing, without changing the speed and course of either vessel. 



(d) Ample sea room to change course in case such maneuver is found 

 necessary. 



(e) Simple means and apparatus involving no calculations or estimates to be 

 made so that an intelligent enlisted man can carry out the method. 



In order to accomplish the above the method proposed contemplates the use 

 of the simplest form of wireless with any efficient form of submarine wireless. 



In case of fog, simultaneous signals are sent from a vessel, and instead of the 

 six characters mentioned above only a single letter or number in the Morse code is 

 necessary to be sent. The 26 letters and 10 numbers each represent 10 degrees of 

 the compass, so that any course is signaled to the nearest 5 degrees, with an aver- 

 age error of less than one-quarter of a point. The observer, using an ordinary 

 double head-piece receiver on another vessel, receives the wireless signal and sub- 

 marine wireless signal, but not simultaneously, as the former is instantaneous while 

 the latter, at 5 miles' distance, for example, arrives more than six seconds later. 



