The humble yet capable marine VHF

Ocean Navigator|July/August 2020

The humble yet capable marine VHF
Although marine VHF radio has been around for a while, it has not only remained useful but is also still a vital part of any vessel’s safety equipment. In fact, VHF units are so capable that many cruisers may not even be aware of all the things they can do. And even with the advent of cellphones, VHFs are still important to any vessel’s communications system.

VHF-based communication came on to the boating scene around the same time FM receivers began showing in up cars back in the ‘60s. This makes sense, as they are both FM radios that have a clearer signal with less static and noise. The drawback to FM radios is that they have a limited range compared to that of the older AM radios. The limited range, however, is more than compensated for by a clear and easily understood signal that is critical in emergency communications.

The USCG does not recommend trying to use a cellphone in place of a VHF radio. In an emergency, a properly installed VHF will not only have a stronger signal but will reach more listeners as well. Being able to broadcast to many listeners at one time will result in faster response in an emergency; a cellphone simply cannot do that.

Like many of the electronic devices we use, VHF radios have improved over the years. Although their basic function remains the same, there have been many added safety features such as digital selective calling (DSC) and automatic identification system (AIS), as well as built-in GPS and the ability to communicate with other onboard electronics. All these new features add a new level of safety and automation to the humble VHF radio.

DSC is a standard for transmitting predefined digital messages and is a core part of the Global Maritime Distress Safety System (GMDSS). This is perhaps the most important safety improvement to VHF radio. What this means is that a VHF radio can now send a digital message to other VHFs and shore stations in an emergency. All new VHFs and many older units have a distress button to use in an emergency. When this button is pressed and held for five seconds, it will send a distress signal to the USCG and other vessels nearby, giving the transmitting vessel’s identification and position. Doing this allows the vessel operator to focus on dealing with whatever emergency is happening, freeing them from having to remain at the radio waiting for a response from potential rescuers. Additionally, it relieves them from having to relay position information, and helps avoid problems with inaccurate or misunderstood information. This is particularly important in the event of a fire or flooding — push the button and get to work saving the boat!

Setup is important

Emergency DSC is great, but it only works if it is properly set up. Many boaters fail to make sure their radios are prepared to take advantage of this system. The first thing that needs to be done when installing a VHF with emergency DSC is to make sure the MMSI number is programed into the memory. A Maritime Mobile Service Identity (MMSI) number is a nine-digit number unique to the vessel, not to the radio. This number is obtained from the FCC, but several organizations such as the U.S. Power Squadrons, Sea Tow and BoatUS have websites to help with the application process. If you plan to operate in international waters outside the U.S., you must get your MMSI number through the FCC. The USCG or other emergency services use this number to identify the vessel and its operators. This will help verify the distress call and speed rescue operations.

If you purchase a used boat, the number will have to be transferred into the new owner’s name. If purchasing a used radio, a new number will have to be programmed; however, most radios only allow the number to be changed once. If more changes are required, the radio may have to be taken to a dealer for reprogramming. If you are considering purchasing a used radio, be sure a new number can be programmed.


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July/August 2020