The different types of apparatus used will produce corresponding variances of pitch and tone, thus giving your ear a chance to compare the sound of a station with its description in Light Lists. The types of apparatus and the sounds produced are as follows: Diaphones create sound by means of slotted reciprocating pistons actuated by compressed air. The resulting sound consists of two tones of different pitch, the first part of the blast being high-pitched, the remainder low. Diaphragm horns are sounded by a disk diaphragm that is vibrated by compressed air, steam, or electricity. Duplex or triplex horn units of differing pitch give a time signal. Reed horns emit sound through a steel reed that is vibrated by compressed air. Sirens produce sound by either a disk or a cupshaped rotor. They are actuated by compressed air, steam, or electricity. Whistles make sound by compressed air or steam admitted through a slot into a cylindrical chamber. Bells are sounded by gas or electricity, or possibly by a hand-hammer; on buoys, wave action is used. RULES OF THE ROAD LEARNING OBJECTIVES: Identify and explain the differences between International and Inland Rules of the Road. As a Signalman, you must become acquainted with basic Rules of the Road. Rules of the Road are published by the Coast Guard in a booklet entitled Navigation Rules, International—Inland, COMDTINST M16672.2B. You should use it to become more familiar with the different Rules of the Road. International Rules are specific rules for all vessels upon the high seas and on connecting waters navigable by seagoing vessels. Inland Rules apply to all vessels upon the inland waters of the United States and to vessels of the United States on the Canadian waters of the Great Lakes to the extent that there is no conflict with Canadian law. International Rules were formalized at the Convention on the International Regulations for Preventing Collisions at Sea, 1972. These rules are commonly called 72 COLREGS. The Inland Navigational Rules discussed in this chapter replace the old Inland Rules, the Western Rivers Rules, the Great Lakes Rules, their respective pilot rules, and parts of the Motorboat Act of 1940. The new rules went into effect on all United States inland waters except the Great Lakes on 24 December 1981. The Inland Rules became effective on the Great Lakes on 1 March 1983. The International/Inland Rules contain the 38 rules that comprise the main body of the rules, and five annexes, which are regulations. The International/ Inland Rules are broken down into five parts as follows: Part A—General Part B—Steering and Sailing Rules Part C—Light and Shapes Part D—Sound and Light Signals Part E—Exemptions STEERING AND SAILING RULES You must understand the Steering and Sailing Rules and be able to apply them to various traffic situations. Although all Rules of the Roads are important, the steering and sailing are the most essential to know to avoid collision. The risk of collision can be considered to exist if the bearing of an approaching vessel does not change within reason. In International Rules, whistle signals are signals of actions; and in Inland Rules, they are signals of intention.  The following is a list of International and Inland whistle signals. SIGNALS INTERNATIONAL    INLAND RULES RULES One short blast I am altering my    I intend to leave you course to starboard on my port side Two short blasts I am altering my I intend to leave you course to port on my starboard side Three short blasts I am operating astern (Same as propulsion International) Five or more short Danger signal (Same as blasts International) One prolonged blast   Will be sounded by a  (Same as vessel when nearing  International) a blind bend around which vision is obscured 9-20