Article by Capt. Steve Katz
Can you hear me now?
While there are many options for communicating while on the water, the fixed mount VHF radio is the best way to communicate with others on land or water. Many boaters bring along cell phones, sat phones, Wi-Fi, inReach and EPIRB’s on their voyage, these are good devices for many purposes but they should not replace marine VHF. Whether to find the best fishing spots, get a tow back to shore or help with a medical emergency, most maritime communication is conducted over the VHF radio.
There are many different varieties of VHF maritime radios, beginning at around $100 for either a stationary radio (fixed mount) or a hand held VHF. Additional features, such as AIS and removable or remote microphones can bring up the costs to over $500.
VHF performance and use
A maritime VHF radio transmits at a government regulated maximum of 25 watts, for an average range of about 25 miles between boats. A VHF radio signal transmits to the receiver radio by line-of sight, so the taller the antenna at each location, the farther the range. As many of you know the US Coast Guard has very tall VHF antenna’s and operates with more power and special technology to send and receive communications over much larger distances than the average boater’s VHF radio. There are 49 VHF channels authorized by the USCG and 7 weather channels used by NOAA Weather Radio. Each channel is assigned a unique frequency between 156 and 162 MHz.
In order for your VHF to send and receive properly, the radio needs to have a good source of power and a good antenna system. While a radio may function on a voltage lower than required, the transmit power output will be reduced and therefore the transmitting range will be reduced also. For example, the popular ICOM M506’s rated output is at a supply voltage of 13.8 volts.
The type, length and connections of the coax cable connecting the radio to the antenna can adversely affect the performance of your VHF radio. There are different types of coax available; generally upgraded coax cable is used for longer runs due to less signal loss.
As an example, high performance RG-8X coax has about a 20% less loss in dB (decibels) that RG-58. The connections in the VHF coax wire can dramatically reduce the power getting to your antenna. A single in-line connection in your coax run can reduce your performance by .5dB, so try to avoid any splices, and if needed, only one splice between the radio and the antenna.
The higher the VHF antenna is mounted above the water, the longer the range of your transmission and reception. Since VHF radio waves travel in a mostly straight line, if your antenna can “see” the other antenna then the radios should be able to send and receive with each other.
Many antennas advertise a “gain” in dB, or apparent increase in output power resulting from efficiency and directivity of the radio waves. An antenna can’t make more power than the VHF radio output, but it can focus the radio waves like a magnifying glass, into a narrow directional beam, effectively increasing the power in that narrow beam. This is great if that narrow beam points to the intended distant VHF radio. But if that narrow beam points up to the moon or down to the water when the boat is rocking on the waves, neighboring boats may not be able to communicate with you since there won’t be much power output in their direction.
Testing
There are a few performance tests a boater or technician can conduct. The first and easiest test is to use your VHF radio to call and talk to a friend on their VHF radio using a proper channel for ship-to-ship communications, but not on Channel 16. The other radio should be a meaningful distance away and known to be in good working order.
You should ask the other party how they hear you and you should listen to see if their signal is loud and clear on your radio. This tests both your send and receive functions along with your microphone and speaker.
You can use the NOAA weather transmission as a reception test too. In this area we get a few weather broadcasts on the VHF weather channels.
Be sure you can receive at least one weather station and you may need to compare your VHF radio reception with another nearby boaters VHF reception at the same time to get a worthy comparison. If you have poor reception and other boaters can hear the broadcast clearly, it could mean you have a radio or antenna problem and will need to look into the situation further.
If you even think you have a VHF problem, you should contact a professional technician who can test your VHF radio and antenna system with specialized equipment, and at a minimum, determine the output power of your radio in watts and check your antenna system loss by calculating the VSWR.
Once you are sure you have a good working VHF radio, there are a few guidelines, rules and laws that you may need to be aware of.
The USCG states ”In general, any vessel equipped with a VHF marine radio-telephone (whether voluntarily or required to) must maintain a watch on Channel 16 (156.800 MHz) whenever the radio-telephone is not being used to communicate.” This is one of the reasons many boaters have two VHF radios. They can leave one VHF tuned to Channel 16 and the other can be used for recreational broadcasts.
An FCC ship station radio license is no longer required for any vessel traveling in United States waters that uses a VHF marine radio, radar or EPIRB, and is not required to carry radio equipment. If your vessel travels outside the USA to a foreign port (including Bahamas, Mexico, etc) or is over 20 meters in length or falls into a few other classifications, you are required to obtain a “ship station license” from the FCC, using FCC Forms 159 and 605.
While there is more VHF information we will discuss in future articles, the information above is a good way to check and test your VHF radio to be sure it is performing at it’s best, allowing you to contact your fishing buddies or communicate with rescue authorities.
Captain Steve Katz is the owner of Steve’s Marine Service and holds NMEA, AMEI and NMEA2000 certificates along with ABYC Master Technician certification and factory training from many manufacturers. To reach Steve, call (631) 264-1600.
