Digital Marine Radio Service

Marine radios on boats use the VHF Marine band and are vital for safety, navigation, and emergency communication. They let vessels contact each other and shore stations, receive weather updates, and send distress calls. However, their biggest limitation is line of sight: both antennas must be able to “see” each other for the signal to work well. At sea, the main obstacle is not buildings or mountains but the Earth’s curvature, which shortens the horizon and limits range. Although radio waves travel about 10% beyond the visible horizon, most power boats can communicate only about 14 miles boat to boat—too short to reach from Los Angeles to Catalina Island. This range depends largely on antenna height above the water. Sailboats usually perform better because their antennas are mounted atop tall masts, giving them a range of about 28 miles between sailboats. To overcome these limits, organizations such as the Coast Guard, Marine Exchange, and Vessel Assist place base stations on high land elevations, increasing line of sight and greatly extending communication range.

Over the years, we have developed radio systems to overcome the line-of-sight limits of terrestrial mobile and portable radios caused by mountains, buildings, and the earth’s curvature. To do this, we built a network of interconnected mountaintop sites that extends coverage into the Pacific Ocean. Many of these sites now reach about 70 miles offshore and span roughly 300 miles, from north of Morro Bay to south of the Mexican border. We do not recommend use south of the Mexican border, as we are not licensed to operate in Mexican waters.

In addition to these advantages, our networked radios provide:
1. The capability to communicate on land, unlike marine radios, which are restricted to specific marine entities. Call home or office.
2. Extended communication range into the ocean, beyond the scope of cell phone coverage.
3. Access to private channels, offering a clear line without the need to filter through unrelated stations or handle interference. Set up channels for an event, a club, or any group you like.
4. Encrypted conversations to ensure privacy and prevent unauthorized monitoring.
5. GPS tracking for both marine- and land-based stations.
6. A tailored emergency alert function.
7. The capacity to manage commercial or personal communications without monopolizing a marine frequency.

Signal Level Map

Mobile and Portable Coverage Map

Google Earth Maps

The maps below can be viewed in Google Earth. These maps contain greater detail than those above.

Signal Level Map

Mobile Coverage

Handheld Coverage

Portable/Mobile

VHF Marine Frequencies
New Channel Number	Old Channel Number	Ship Transmit MHz	Ship Receive MHz	Use
1001	01A	156.050	156.050	Port Operations and Commercial, VTS. Available only in New Orleans / Lower Mississippi area.
1005	05A	156.250	156.250	Port Operations or VTS in the Houston, New Orleans and Seattle areas.
06	06	156.300	156.300	Inter ship Safety
1007	07A	156.350	156.350	Commercial. VDSMS
08	08	156.400	156.400	Commercial (Intership only). VDSMS
09	09	156.450	156.450	Boater Calling. Commercial and Non-Commercial. VDSMS
10	10	156.500	156.500	Commercial. VDSMS
11	11	156.550	156.550	Commercial. VTS in selected areas. VDSMS
12	12	156.600	156.600	Port Operations. VTS in selected areas.
13	13	156.650	156.650	Intership Navigation Safety (Bridge-to-bridge). Ships >20m length maintain a listening watch on this channel in US waters.
14	14	156.700	156.700	Port Operations. VTS in selected areas.
15	15	—	156.750	Environmental (Receive only). Used by Class C EPIRBs.
16	16	156.800	156.800	International Distress, Safety and Calling. Ships required to carry radio, USCG, and most coast stations maintain a listening watch on this channel.
17	17	156.850	156.850	State & local govt maritime control
1018	18A	156.900	156.900	Commercial. VDSMS
1019	19A	156.950	156.950	Commercial. VDSMS
20	20	157.000	161.600	Port Operations (duplex)
1020	20A	157.000	157.000	Port Operations
1021	21A	157.050	157.050	U.S. Coast Guard only
1022	22A	157.100	157.100	Coast Guard Liaison and Maritime Safety Information Broadcasts. Broadcasts announced on channel 16.
1023	23A	157.150	157.150	U.S. Coast Guard only
24	24	157.200	161.800	Public Correspondence (Marine Operator). VDSMS
25	25	157.250	161.850	Public Correspondence (Marine Operator). VDSMS
26	26	157.300	161.900	Public Correspondence (Marine Operator). VDSMS
27	27	157.350	161.950	Public Correspondence (Marine Operator). VDSMS. Radio test feature coming soon.
28	28	157.400	162.000	Public Correspondence (Marine Operator). VDSMS
1063	63A	156.175	156.175	Port Operations and Commercial, VTS. Available only in New Orleans / Lower Mississippi area.
1065	65A	156.275	156.275	Port Operations
1066	66A	156.325	156.325	Port Operations
67	67	156.375	156.375	Commercial. Used for Bridge-to-bridge communications in lower Mississippi River. Inter ship only.
68	68	156.425	156.425	Non-Commercial. VDSMS
69	69	156.475	156.475	Non-Commercial. VDSMS
70	70	156.525	156.525	Digital Selective Calling (voice communications not allowed)
71	71	156.575	156.575	Non-Commercial. VDSMS
72	72	156.625	156.625	Non-Commercial (Inter ship only). VDSMS
73	73	156.675	156.675	Port Operations
74	74	156.725	156.725	Port Operations
77	77	156.875	156.875	Port Operations (Inter ship only)
1078	78A	156.925	156.925	Non-Commercial. VDSMS
1079	79A	156.975	156.975	Commercial. Non-Commercial in Great Lakes only. VDSMS
1080	80A	157.025	157.025	Commercial. Non-Commercial in Great Lakes only. VDSMS
1081	81A	157.075	157.075	U.S. Government only – Environmental protection operations.
1082	82A	157.125	157.125	U.S. Government only
1083	83A	157.175	157.175	U.S. Coast Guard only
84	84	157.225	161.825	Public Correspondence (Marine Operator). VDSMS
85	85	157.275	161.875	Public Correspondence (Marine Operator). VDSMS
86	86	157.325	161.925	Public Correspondence (Marine Operator). VDSMS
87	87	157.375	157.375	Public Correspondence (Marine Operator). VDSMS
88	88	157.425	157.425	Commercial, Intership only. VDSMS
AIS 1	AIS 1	161.975	161.975	Automatic Identification System (AIS)
AIS 2	AIS 2	162.025	162.025	Automatic Identification System (AIS)