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COMMUNICATIONS, as A\oplied to the Merchant Marine transfer of ideas from one per- son to another, regardless of the location of the two parties in- volved, or the means by which the transfer is effected. Since prehistoric times, ships have utilized the seas for the same purposes as we do today, but until the advent of the twentieth century the only means of communi- cation between ship and ship or be- tween ship and shore, was obtained when within visual touch using the voice, smoke, whistles, flares, rock- ets, flags, or hoisted shapes. Other- wise, every vessel was cut off from the rest of the world by an apparent- ly unbridgeable extent of space, pre- venting the exchange of ideas, or communication, which we find so in- dispensable now. Ctranster ot icea is defined as a Rapid Development of Radio The desirability of effecting a means of communicating with ships at sea was so obvious that after the first stages of radio development were successful, the new system was im- mediately and wholly utilized for maritime communication purposes. Although recognized as a magnificent achievement, few visualized, during those first few years of radio, how rapid would be its future develop- ment; how many useful applications would be discovered; how radio com- munication would become an integral part of the world’s routine life. Although radio progress has re- sulted in the formation of a distinct and quite complicated technical proc- ess, neither the general public nor the seafarer looks upon radio any longer as a mystical novelty. They see it now only as a commonplace established service, and are rapidly forgetting the days when maritime communication was considered a fantastic dream. The value of radio communication is peculiarly realized by the seaman, since it furnishes him with the de- sired link to man’s habitat and base, the shore. It also assists him in navigating the seas and in bringing assistance when in distress. Today, there is no scientific reason for any merchant ship, large or small, in any part of the world, to be denied the invaluable contact with the land af- *The author, Capt: S: CC: Hooper, U. S. N., is director, naval commu- nications, United States navy. This article is being published in two parts. The second part will appear in the September issue. HE safety of life and property at sea often depends directly on the skilful use of established methods of communication. In this interesting article the author discusses their possibilities and limitations. |t is the duty. of every deck officer to acquire a thorough knowledge of all means of communication and to perfect himself in their effective practical application under the most difficult conditions. Only in this way can full advantage be taken of the extraordinary advances of modern science in aids to navigation. forded so conveniently by radio. Naturally, the first radio installa- tions were crude affairs and could be relied upon only over short dis- tances, but it was soon discovered that better equipment was possible and that the propagation character- istic of the various radio waves or frequencies on which signals were transmitted were decidedly different. The latter discovery was of far- reaching consequence, resulting in the first reliable long distance radio communication on what is now known as low frequency—between 10 and 100 kilocyeles (30,000 and 3000 meters). Transmitting ranges were also greatly increased on other fre- quencies, now known as medium fre- quencies, but it was not until com- paratively recent years that effective transmission was accomplished on frequencies above 4000 kilocycles, which, with suitable power and choice of frequency, can effect reliable com- munication to almost any point on the surface of the earth. Value of Radio Communications It is superfluous to say that radio is with us as a permanent fixture. Though technical methods and appli- cations may vary, the process of ex- changing ideas between one location and another, using means involving no actual physical connection by wires or other man-made conveyors, affords mankind one of its greatest boons. It is also obvious that the personnel of our merchant marine MARINE REvieEw—August, 1934 BY CAPI, S. ©. COVER is well aware of the value of radio communication and will be thrown in contact with it more and more as developments progress. This fact ealls for a certain amount of knowl- edge of radio communications on the part of merchant marine officers in order to fulfill their duties in an ac- ceptable manner. It therefore ap- pears desirable to explore further the applications of radio to the neces- sities of the merchant marine. Applications of Marine Radio The indispensable aid which radio offers to ships at sea may be divided into the following components or phases: (1) Distress Communications. (2) Navigational Aids. (3) Commercial Communications. Even if the radio could be used only in connection with distress communi- cations, it would be of inestimable value. The addition of the other two components has afforded advantages to world-wide shipping which, twenty years ago, were never visioned. An outline of each of the services men- tioned above will show exactly how radio assists our sea-borne com- merce and citizens who travel by water. Distress Communications This, the first of the components or phases of communications above, may be divided into the following parts: (a) Distress Signals. (b) Rescue Communications. Distress Signals Nowadays, few persons would con- sider a sea voyage on a ship not equipped with radio transmitting and receiving apparatus. The number of lives which radio has saved at sea is not accurately known, but the aver- age person throughout the world realizes fully what radio has done and is capable of doing for the mariner and traveler. International agreement provides for the form, power, and frequency upon which a distress signal may be sent wlienever a vessel finds herself with disaster imminent. Every ship equipped with radio and certain designated shore radio sta- tions all over the world are required to stand a watch on the prescribed distress frequency of 500 kilocycles (600 meters), either continuously or for definite periods during every hour of the day. All vessels or sta- 15