U.S. Coast Guard Radio Procedures
Posted: Sat Jul 13, 2024 11:17 am
On Saturday July 13, 2024, there was a lot of USCG radio communication activity in my area, related (I presume) to the "Boyne Thunder" poker run, which is an annual event up here in northern Lake Michigan and Grand Traverse Bay, and this year has about 100 boats participating. By listening to VHF Marine Radio on Channels 15, 16, 21A, and 22A, I am hearing a lot of traffic between "sector" (which is USCG Sector Northern Great Lakes radio) and various on-the-water and in-the-air assets.
Listening to the radio chatter has been interesting, and I observed a new radio procedure: in giving information by voice some of the radio operators were using the spoken word "tack" to indicate a hyphen. I investigated the use of the spoken word "tack" to indicate a hyphen, and found that it apparently stems from the spoken interpretation of flag signals. Here is an excerpt from a chapter in a naval training manual called "ALLIED FLAGHOIST PROCEDURE":
Another interesting bit of jargon: some assets were transmitting their "GAR score." After a bit of research I discovered that the "GAR score" is a numerical representation of the outcome of a risk assessment by the asset using the GAR model as in GAR means "general assessment of risk", and is used by the surface assets to report their status to higher levels in the operation of the evolution or event. The GAR scores reported were indicative of minimal risk for the event or evolution in which the assets were participating.
The weather was perfect for the event, sunny, warm, blue sky, and just enough wind to disturb the water surface which helps these high-speed boats run faster. I saw several of the big boys coming in at what was probably 70-MPH and their ride was steady, no bow movement noticed at all, just screaming on plane with trim almost perfectly level with the water.
Listening to the radio chatter has been interesting, and I observed a new radio procedure: in giving information by voice some of the radio operators were using the spoken word "tack" to indicate a hyphen. I investigated the use of the spoken word "tack" to indicate a hyphen, and found that it apparently stems from the spoken interpretation of flag signals. Here is an excerpt from a chapter in a naval training manual called "ALLIED FLAGHOIST PROCEDURE":
- In addition to the 68 flags in the bag, you have a tackline. A tackline is a length of halyard approximately 6 feet long; the exact length depends upon the size of flags in use. The tackline is transmitted and spoken as tack and is written as a dash (hyphen) "-". It is used to avoid ambiguity. It separates signals or groups of numerals that, if not separated, could convey a different meaning from that intended.
Example:
If the signal SL2 means “Prepare to receive personnel casualties,” TACK would be inserted between the digit 2 and the given number of casualties: SL2 TACK 27.
TACK also is used to separate range and bearing figures. If C3 means “Investigate possible sighting,” the signal might be C3 TACK 345 TACK 20, indicating the sighting at a bearing of 345 and a distance of 20 miles.
Another interesting bit of jargon: some assets were transmitting their "GAR score." After a bit of research I discovered that the "GAR score" is a numerical representation of the outcome of a risk assessment by the asset using the GAR model as in GAR means "general assessment of risk", and is used by the surface assets to report their status to higher levels in the operation of the evolution or event. The GAR scores reported were indicative of minimal risk for the event or evolution in which the assets were participating.
The weather was perfect for the event, sunny, warm, blue sky, and just enough wind to disturb the water surface which helps these high-speed boats run faster. I saw several of the big boys coming in at what was probably 70-MPH and their ride was steady, no bow movement noticed at all, just screaming on plane with trim almost perfectly level with the water.