Bridge Terminology

Communications Equipment

• Secure/Unsecure Radiotelephone (R/T) Handsets and RHMS Controls. Provide secure voice communications between various units of the fleet. Unsecured provides voice or teletype communications between various units through UHF, VHF and HF transceivers.
• Sound-powered Phones and Growlers. Primary source of shipboard communications since they require no external power for operation.
• Ship's Whistle. Used primarily for warning other ships of your own ship's intentions or executions. Two blasts for port turn and one blast for starboard turn, five or more blasts for an emergency.
• 1MC General Announcing System. Central amplified announcing system designed to furnish amplified voice communications and alarm signals to the various speaker systems over the entire ship. Master control that provides the microphone and switches for the various receiving groups is located on bridge, quarterdeck, and AA (Anti-Aircraft) stations.
• 21MC. CO's command circuit which provides communications with various command stations such as CIC, main control, etc.
• X1J Sound Power Phone System. Auxiliary ship administration circuit.
• Voice Tubes. Used as a means of communication between secondary conn and the bridge. On smaller ships, it is used for communications between the bridge and CO's cabin.
• Pneumatic Tubes. Provide for communication between radio, CIC, bridge, and other strategic locations by means of written messages placed in shuttles that move through tubes by using vacuum. They are used since there is no possibility of message interception.
• Call Bell/"E" Call System. Various circuits for notification of communications.
• Ship's Service Telephone. Basic hard wired dial telephone system used throughout the ship via a telephone switchboard.  
• Underwater Telephone (Gertrude). Use primarily during EMCON (no electronic emission) conditions for communications between various units, with a range of 3 to 4 miles.