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At random: On August 17, 1958, the USS SKATE circumnavigated the globe in about fifty minutes. The SKATE was at a radius of about two miles from the North Pole at the time, and the distance traveled in the circumnavigation was about twelve miles.
The 1MC
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Corabelle
Posted 2007-10-13 8:24 AM (#8160)


COMSUBBBS

Posts: 2561

Location: Rapid City, SD
Subject: The 1MC

I'm guessing that this is some type of loud speaker system on the boat. Is this (initials & system) the same on skimmers? What do the initials stand for?

Cora


Roy Ator
Posted 2007-10-13 9:10 AM (#8161 - in reply to #8160)


Great Sage of the Sea

Posts: 892

Location: Palo Pinto County, Texas
Subject: RE: The 1MC

U.S. Navy vessels use both powered and non-powered circuits for interior communications. There is an enlisted rating called an Interior Communications Electrician [IC] that maintains these systems. The non-powered is called sound powered phones. They are manned with head sets when at battle stations. At other times they use a handset that may be called with a hand cranked growler system. The powered systems all have an alphanumeric designator (1MC, 5MC, 7MC, 21MC, etc.). Most are two way communication circuits. However the 1MC is a general announcing and alarm system that broadcasts to all normally occupied compartments and topside. For the most part these circuit designators are common to all Navy ships and submarines.
Thomas Courtien
Posted 2007-10-13 9:18 AM (#8162 - in reply to #8160)
Master and Commander

Posts: 1890

Location: Patterson, New York
Subject: RE: The 1MC

The memory is fuzzy but I think the 1MC on the 640 Class could only be used from the Control Room/Conn and The Main Engine Room control station.

Anyone remember this detail?
RCK
Posted 2007-10-13 10:50 AM (#8166 - in reply to #8160)
Master and Commander

Posts: 1431

Subject: RE: The 1MC

MC stands for "main circuit"
Donald L. Johnson
Posted 2007-10-14 9:17 PM (#8195 - in reply to #8166)


Great Sage of the Sea

Posts: 602

Location: Visalia, Ca.
Subject: RE: The 1MC

RCK - 2007-10-13 8:50 AM

MC stands for "main circuit"


I was an IC Electrician before Rickover took away my telephone and made me an Electrician's Mate in 1983. "Main Circuit" is not the way I remember it, because most of the MC circuits are not "main", but auxilliary or limited use circuits, confined to a particular set of spaces or uses, such as the 27MC "squack-box" for sonar/radio/ECM control, the 31MC for Submarine Escape Trunks, or the 4MC Emergency Reporting circuit.

My recollection is that the "MC" designation stands for "Mass Communications", but I can't find it defined in either my 1973 or 2002 Blue Jackets' Manuals, or my 1980's-vintage IC3 and IC2 Rate Training Manuals.



Donald L. Johnson
Posted 2007-10-14 9:26 PM (#8196 - in reply to #8162)


Great Sage of the Sea

Posts: 602

Location: Visalia, Ca.
Subject: RE: The 1MC

Thomas Courtien - 2007-10-13 7:18 AM

The memory is fuzzy but I think the 1MC on the 640 Class could only be used from the Control Room/Conn and The Main Engine Room control station.

Anyone remember this detail?


My recollection is that the 1MC microphones were on the Conn and the Bridge suitcase.
Manuevering had 2MC for the Engineering Spaces and 7MC for talking to the Conn/Bridge/Wardroom.

"The following is a test of the 1MC from Topside, Manuevering acknowledge on the 7MC."


SOB490
Posted 2007-10-15 2:34 PM (#8217 - in reply to #8196)


Old Salt

Posts: 489

Location: San Freakcisco CA area
Subject: RE: The 1MC

I've seen an official NavShips document that designates the IC circuits according to function - and like a lot of the JAN/MilSpec type stuff, the letters used in the designations have no literal meaning - their value is in consistency of use.

However, I've seen distinctions made between externally powered IC circuits and self-powered circuits, i.e. 1MC, 7MC, 21MC, etc and JA, XJA, JV, XJV, etc. but again, I've never seen anything that says "MC" has a literal meaning such as "main circuit" or "JV" as "just voice," whatever.

If someone has access to a NavShips Technical Manual (or the "real" bible - BSTM for BuShips Technical Manual) I'm sure you'll find it there. Someone posted a listing of IC circuit designators on Roundtini's BBS a few years back ... Whalen? Wuzzat you?

Edited by SOB490 2007-10-15 2:35 PM
whalen
Posted 2007-10-15 6:37 PM (#8223 - in reply to #8217)


Great Sage of the Sea

Posts: 606

Location: Citrus County FL
Subject: The rest of the MC circuits

SYSTEM CIRCUIT SYSTEM 
1MC General 
2MC Propulsion plant 
3MC Aviators 
4MC Damage control 
5MC Flight deck 
6MC Intership 
7MC Submarine control 
8MC Troop administration and control 
9MC Underwater troop communication 
18MC Bridge 
19MC Aviation Control 
21MC Captain’s command 
22MC Electronic control 
23MC Electrical control 
24MC Flag command
26MC Machinery control 
27MC Sonar and radar control 
29MC Sonar control and information 
30MC Special weapons 
31MC Escape truck 
32MC Weapons control 
35MC Launcher captains’ 
39MC Cargo handling 
40MC Flag administration 
42MC CIC coordinating
43MC Unassigned 
44MC Instrumentation space 
45MC Research operations
46MC Aviation ordnance and missile handling 
47MC Torpedo control 
49MC Unassigned 
50MC Integrated operational intelligence center 
51MC Aircraft maintenance and handling control 
52MC Unassigned 
53MC Ship administration 
54MC Repair officer’s control 
55MC Sonar service 
56MC Unassigned 
57MC Unassigned 
58MC Hangar deck damage control
59MC SAMID alert 
Chew
Posted 2007-10-16 6:13 AM (#8227 - in reply to #8160)


Mess cooking

Posts: 48

Location: No. CA
Subject: RE: The 1MC

Not that I would stake my life on it, but the 1MC could be used from Manuvering (619, 608). The actual use of it should be well thought out.

bob
RCK
Posted 2007-10-16 7:47 AM (#8232 - in reply to #8160)
Master and Commander

Posts: 1431

Subject: RE: The 1MC

This is a list of communication systems found aboard U.S.Subs. It doesent say what "MC" stands for but that was one of the questions that I was asked during my qualifcaton walk through with the Engineering officer and I got it right. "MC' stands for main communication circuit. That's my story and I'm sticking to it.

All ships including submarines have internal communications systems. In general they can be broken down into these categories:
Alarm system
The alarm system is integrated into the 1MC System. It consists of four signal generator modules, each one producing a specific sound.
General Alarm - A gong sound, used for emergencies and battle stations.
Duration: As long as necessary, about 6 seconds.
Diving Alarm - A klaxon sound (See below for Diesel boats) - Used for diving and surfacing. Duration: Diving, sound two times then quit. Surfacing, sound three times then quit.
Collision Alarm - A pulsing siren sound - Used for eminent collision warning.
Duration: As long as necessary, about 7-10 seconds.
Reactor or Power Plant Alarm - A pair of alternating high and low tones, similar to a European siren. Only on nuclear submarines. Duration: As long as necessary, about 7-10 seconds.
The Diesel submarines had electric, motor driven, klaxons dispersed throughout the boat. The modern signal is an approximate simulation. The general and collision alarms were generated by electronic modules.
You can sample four of the alarms below:
Click here for a General Alarm. (2.6 seconds)
Click here for a modern klaxon Diving Alarm. (Sounds 2 times, 3.6 seconds)
Click here for a mechanical klaxon Surface Alarm. (Sounds 3 times, 6.3 seconds)
Click here for a Collision Alarm. (7.8 seconds)
Click here for a Reactor or Power Plant Alarm (4.0 seconds). *It still sounds the same.


Klaxon Class H MC Speaker


Announcing systems

1MC General Announcing - Used only as authorized by the O.O.D..

Submarine General Announcing Groups:
All - Ship wide
Weather Deck Forward (Diesel boats)
Weather Deck Aft (Diesel boats)
Engine Rooms (Diesel boats)
Upper & Main Deck Passages, Mess, Lounges, Galley (Diesel boats)
Lower Deck Passageways, Shaft Alley, Steering Gear Room (Diesel boats)
2MC Engineering Announcing - Propulsion Plant Engineering machinery spaces only

4MC Damage Control 2-way Emergency Reporting Announcing used with the XJA system.
Various sound powered phone hand sets throughout the ship have 4MC selectors.
When 4MC is selected the sound powered phone user can broadcast on the 4MC.
Intercom systems

7MC General Announcing 2-way - Ship Control or Maneuvering Announcing

21MC Captain's Command 2-way - Bridge, Conn & other stations

22MC Radio Room / Electronic Control 2-way

27MC Sonar Control 2-way - Sonar Supervisor

31MC Escape Hatch Announcing 2-way

47 MC Weapons - Fire Control & Torpedo Room

On Diesel boats:

The general announcing system is comprised of two voice communications circuits, one-way (1MC) and two-way (7MC). The same amplifier equipment is used for both circuits. Generally, one channel is used for the 1MC and one for the 7MC, but in an emergency both circuits may be operated through either of the two individual amplifier channels.
Telephone systems

JA, XJA - Sound Powered Phone System (SPT) Circuits

The sound powered phone system is a telephone system in which the power comes from the sound of the voice. Vibrations from the voice cause a diaphragm to vibrate. Attached to the diaphragm is a delicate needle, or armature, that is surrounded by a fine wire coil held in place by a magnet. The movement of the armature inside the coil induces current which is transmitted through the line to a receiver. The receiver is constructed exactly like the transmitter. The current from the transmitter passes through the coil on the receiver and causes the diaphragm to vibrate and reproduce the speaker's voice. The system is divided into two circuits, the XJA (handset) used for routine ship's service communication, and the JA (headset) used on all battle control stations.
E - Telephone Call Annunciator System (between SPTs) "Growler" multi-station Intercom

3EM - Telephone Call Annunciator System - Engineering (between SPTs) "Growler" multi-
station Intercom
The telephone call annunciator system consists of hand cranked signal generators located in each compartment and require no supply voltage. Often referred to as "growlers" each unit consists of a selector rotary switch used to select the compartment desired and a small speaker that "growls" on the receiver unit to notify the compartment of an incoming call. It is a separate complete circuit and is not connected to the phone systems.
"White Rat" - Speaker system in maneuvering that monitors all engineering spaces
sound powered phones.

Dial X - Internal Dial telephone System (nuke boats only, replaced with non-mechanical on new boats)

Indicator systems

The rest of the IC systems are too numerous to mention. Some examples are; Gyrocompass and repeaters, Engine Order Telegraph, Digital Depth Gauge, Bilge alarms, Underwater log, Atmosphere Monitors, Ship's Entertainment systems, Planes and Rudder Angle indicators and, Salinity Cells.

Sources:

USS Pampanito museum http://www.maritime.org/radiocat.htm

Battleship New Jersey Amateur Radio Station http://www.qsl.net/bb62/

Jerry Uffelman IC1(SS)

*Power Plant Alarm sound verified at T.T.F. Kingsland, GA 7/05





Runner485
Posted 2007-10-16 3:33 PM (#8240 - in reply to #8160)


COMSUBBBS

Posts: 2672

Location: New Jersey
Subject: RE: The 1MC

Corabelle - 2007-10-13 8:24 AM

I'm guessing that this is some type of loud speaker system on the boat. Is this (initials & system) the same on skimmers? What do the initials stand for?

Cora




1MC
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