Range of USCG RESCUE21 System

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
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Range of USCG RESCUE21 System

Postby Tesoro » Wed Sep 29, 2021 10:43 am

With the new U.S. Coast Guard Rescue 21 system a 1-Watt handheld radio with antenna 6-feet above the water gives you a guaranteed 30-Mile range [Moderator's note: this is not correct; see comments below] offshore anywhere on east and west coast to talk to the Coast Guard.

[Moderator's note: separated from a now deleted discussion and reduced to only the comment about RESCUE 21.]

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Location: Michigan, Lower Peninsula

Re: Range of USCG RESCUE21 System

Postby jimh » Sun Oct 03, 2021 9:25 am

I believe that the actual specification that the USCG RESCUE 21 coastal radio system is designed to meet is to detect a transmission from a 1-Watt radio with antenna at 2-meters (about 6.5-feet) above the water made for a duration of 1-second that is 20-Nautical-Miles offshore--about 23 statute miles--not "30-miles" (in either nautical miles or statute miles). The notion that a range of 30-miles is "guaranteed" is not correct.

There can certainly be locations in which the RESCUE 21 system provides coverage to farther than 20-nautical-miles offshorebut that range is not to be expected or relied upon. The range from the actual land station location to the ship station can be greater than 20-nautical-miles, as the specification requires the coverage to be 20-nautical-miles to seaward. While most RESCUE 21 stations are located near the coastline, many are located inland to take advantage of high elevation sites available. The higher antenna site improves the coverage range and compensates for the station being inland from the coast.

Also the RESCUE 21 system covers many areas other than the east and west ocean coasts of the United States. The entire Great Lakes are covered, other than the Canadian portions, as well are Alaska, Purto Rico, Guam, and some inland waterways. For example, there are 28 RESCUE 21 stations in Michigan alone covering the several thousand-mile-long coastline of Michigan for 20-miles to seaward. There are more RESCUE 21 installation in Michigan than in any other state.

The RESCUE 21 system is described in several other articles. See

RESCUE 21 Radio Stations
https://www.continuouswave.com/whaler/r ... tions.html
This is long and illustrated article that describes in detail the RESCUE 21 stations

RESCUE 21 Maintenance Contract

RESCUE 21 Sites in the Great Lakes

A Long Story of an AIS Hunt

Regarding the "new" aspect of RESCUE 21, the last installation was completed in 2017. The process was begun in 1995, and took more than 20-years to be completed. Some further history is given at

https://www.dcms.uscg.mil/Our-Organizat ... 21_103117/

The initial operating capacity stage was reached in December 2005, about 16 years ago. Whether a 16-year-old operational system is still considered to be "new" is speculative.