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ContinuousWave: Small Boat Electrical
VHF Marine Band Hand Held Radio
|Author||Topic: VHF Marine Band Hand Held Radio|
posted 12-02-2012 10:00 AM ET (US)
Recently there has been a tidal wave of television real-life documentary shows about the United States Coast Guard appearing on cable television. The other day one channel was showing hours and hours of episodes of USCG rescues, many involving helicopters. Of course, having not seen any of these when they originally aired as a weekly serial program, I had to watch them.
I noticed that in several cases the USCG helicopter would arrive on the scene of a vessel in distress but be unable to establish radio contact with the vessel. The helicopter would then lower a hand held VHF marine band radio preset to their working channel to the vessel. In most cases it looked like the vessel should have had a radio onboard. I have to presume--it was never explained in the television docu-drama--that these vessels had lost their radio communication. The most likely cause for that would be loss of battery power, perhaps due to flooding of the batteries. All of these incidents were talking place in saltwater.
I don't know if a 12-Volt storage battery goes dead immediately when immersed in saltwater. If the battery is an open-vent battery the ingress of seawater might be a problem. A sealed battery might hold up for quite a while. Pure freshwater is not a good conductor, and I think a sealed battery immersed in freshwater might hold up for a long time.
Or, perhap something else happened to all the radios on these boats in distress. Maybe their antennas broke off--but even a radio with no antenna ought to be able to talk 50-feet to a helicopter overhead.
In any case, all these boaters were without a radio and they were on boats that were in distress--not a good situation.
Also, this summer, while we were boating with a group of friends, we got into some rough water. One of the boats lost its main radio. (I think something in the power wiring came loose in the rough seas.) However, this boat crew had a hand held radio onboard, and they switched to that for communication. This was really very important, because we were not in visual contact with them, and if they had not replied to our radio call we would have been very worried. We would have had to go look for them, and in the seas we were in that would not have been easy or pleasant. That they had a secondary radio onboard was very helpful, both for them and for us.
A VHF Marine Band Radio is really a very important asset to have on a small boat. As demonstrated in the above examples, a working VHF Marine Band radio is so important that it is not really excessive to have two of them on a boat, even on a small boat.
A hand held radio is totally independent of the main radio. It has its own battery, its own antenna, its own microphone and speaker. Even if you have two fixed-mount radios on a boat, they probably share a common battery for power. A hand held radio is truly independent of the boat.
posted 12-02-2012 12:42 PM ET (US)
Jim I totally agree with you.
As you know I travel pretty heavy when it comes to VHF radios.
I am considering purchasing a new Standard Horizon DSC/GPS hand held. I think a hand held with a built in GPS and DSC capabilities would be a great emergency radio. The coast of these units is down to about $200.
posted 02-08-2013 09:14 PM ET (US)
There has been some recent changes to the global plan for assignment of marine mobile service identities (MMSI). The changes are described in an International Telecommunications Union (ITU) document:
In Annex II, Section 1 of the recommendation, there is a specific plan laid out for assignment of an MMSI for handheld DSC radios with global navigation satellite system (GNSS) receivers. (For boaters in North America the GNSS receiver would typically be a U.S. Air Force GPS receiver.)
Let me explain the plan by using my own MMSI as an example. From the FCC, I obtained an MMSI: 367501930. In all existing MMSI numbers, the first three numbers are known as the Marine Identification Digits or MID. The MID represents the code for the administration having jurisdiction over the the ship station that is identified in the MMSI. (The first digit of the MID also appears to identify the continent of the administration with jurisdiction. A "3" means North American, Caribbean, or Central America. The "367" means USA.)
The next portion of the MMSI is the "ship station number," and in my case that is 501930. It is very common for the ship station number to have one or more trailing zero. Apparently there is some historical reason for padding out the MMSI with a trailing zero in order to make the MMSI reach a total of nine digits in length. (I suspect there are some good reason for this. It may have been done to help backward compatibility with legacy systems. Let's ignore that for the moment.)
The new ITU recommendation M.585-6 provides for a very convenient scheme to identify handheld radios that are associated with a particular vessel by using the MMSI of the vessel to generate a new MMSI for the handheld radio. I believe there is a presumption that a handheld radio associated with a particular vessel would retain that vessel's MMSI, but delete the trailing zero and append a leading "8." For example, in the case of my boat, my radios would be identified as follows:
Main vessel radio MMSI = 367501930
The notion that a handheld radio ought to have a special form of MMSI is based on permitting recognition of transmissions from the radio to be of limited range and limited battery life. The leading "8" in the MMSI identifies the radio as being a handheld and being associated with a vessel. This is intended to convey additional information about the source of a transmission in an emergency situation.
This recommendation is from the International Telecommunications Union. I suspect it will be up to the FCC in the USA to adopt this policy and authorize its use. I don't know what the status of this recommendation is for radios in the USA.
It does not take a extraordinarily detailed look at the MMSI situation to see that there are already some problems. Not every nine-digit MMSI ends in a zero. For example, the MMSI's issued by BoatUS in their registration program can apparently end in any digit. I have a BoatUS registry MMSI. It is nine-digits long and ends in a "9." This is new MMSI number plan for handheld radios is clearly not going to work for the BoatUS registered MMSI vessels.
For more on this topic:
List of MID codes for registering authorities:
Good reference on MMSI in general:
Excerpt from the recommendation cited above:
posted 02-08-2013 09:31 PM ET (US)
The recommendation says:
If going by past practices, I suspect that in the USA the FCC will probably want to be involved in the process.
posted 02-10-2013 08:44 AM ET (US)
There are at least three hand held radios on the market at present that offer a GNSS receiver and DSC capabilities:
The DSC capabilities of these radios may not meet the Class-D requirement. This is understandable. One of the requirements of Class-D is to have a separate receiver dedicated to monitoring Channel 70 for DSC calls. The hand held radios tend to meet the older and less stringent requirements of Radio Technical Committee for Maritine, Special Committee 101 (often referred to as just RTCM SC-101). This type of DSC radio was only recognized in the USA, and radios, like these handhelds, which are only qualified to RTCM SC-101 may not be used in Europe for DSC radios.
posted 02-14-2013 08:35 AM ET (US)
SIMRAD have announced a new VHF Marine Band hand-held radio model HH-36 with GNSS receiver and DSC to CLASS-D. This is quite a jump in hand-held radio and DSC, being certified to CLASS-D rating. The details are available at
Lowrance may be introducing their version of this radio as the LINK-2, but have not yet revealed any literature.
The HH-36 floats and is rated waterproof to JIS-7. The LCD display is also said to be larger than any other similar radio.
posted 02-14-2013 08:40 AM ET (US)
West Marine already have the soon-to-be-announced Lowrance LINK-2 hand-held VHF Marine Band radio with GNSS and DSC on their website.
posted 02-14-2013 09:07 AM ET (US)
Here is the feature list of the LINK-2:
VHF/DSC features and functionality
GPS features and functionality
Navigation functions (setting waypoints and creating GOTO route)
General features and functionality
UPDATE: this same information has now been posted to Lowrance's website.
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