Vhf Marine Communication Equipment | Electronics and Navigation Hinelson
Welcome to the page of our e-commerce dedicated to the online sale of nautical VHF radios. As is well known, the VHF radio is compulsory for all recreational vessels qualified for navigation beyond 6 miles from the coast: the regulations, in this sense, do not make any difference between portable or fixed VHF, but those who have nautical experience know well that, for safety, it would be definitely the case to have both types of equipment on board one's boat. It must be underlined that, as foreseen by art. 29 of Legislative Decree 18/07/2005 n.171,...

Welcome to the page of our e-commerce dedicated to the online sale of nautical VHF radios. As is well known, the VHF radio is compulsory for all recreational vessels qualified for navigation beyond 6 miles from the coast: the regulations, in this sense, do not make any difference between portable or fixed VHF, but those who have nautical experience know well that, for safety, it would be definitely the case to have both types of equipment on board one's boat. It must be underlined that, as foreseen by art. 29 of Legislative Decree 18/07/2005 n.171, in order to use this particular transceiver for boats, an RTF operating licence is necessary (and not only, as we will see later).

VHF: what is it?

Nautical VHF is a radio transmitter used for communications at sea: its peculiarity is that it works on very high frequencies. And it is precisely this peculiarity that makes the VHF system perfect for recreational units that sail far from the coast, as these high frequencies allow for clear distance communication that is less influenced by atmospheric agents or other signals that cross the airwaves.

Specifically, the VHF (or Very High Frequency) radio waves of radio transmitters for boats are waves between 156 and 174 MHz. Looking instead at the wavelength, we are talking in principle about 3 metres - whereas, to make a comparison, the medium frequency radio waves of AM radio transmissions work on wavelengths greater than 100 metres.

Marine VHF: mandatory documentation

There is a great deal of confusion regarding the documents necessary to use a VHF device on one's boat. As anticipated, this radio transmitter, fixed or mobile, is mandatory for all pleasure craft that can navigate beyond 6 miles. In many cases, however, these devices have been extremely useful also in the case of boats that navigate much closer to the coast, and for this reason the advice is always to equip one's own boat with a marine VHF to be used in case of need, whatever the distance from the coast.

In all cases, however, it is necessary to accompany one's VHF with the RTF Limited Certificate, which can be obtained without any course and without any examination: it is sufficient to submit a special application to the Ministry of Economic Development (which has taken over from the old Ministry of Communications). This certificate is the same for any type of VHF radio for boats and never expires.

The RTF Limited Certificate is, however, only the first of the mandatory documents for the use of a VHF radio. In fact, it must also be accompanied by the License to operate VHF equipment, which, in spite of the fact that some people still think the contrary, is also absolutely necessary for the use of the portable VHF. Unlike the Certificate mentioned above, in this case it must be underlined that the Licence varies according to the type of vehicle on which the VHF radio is installed: this means that there are different licences for VHF equipment on simple vessels and on real boats. Each Licence, therefore, is indissolubly linked to a specific unit. Also in this case, on the other hand, no course or examination is necessary: it will be sufficient to make an express request for the Licence at the Ministry of Economic Development. The document, however, has a duration of only 10 years, and must be replaced both in case of transfer of the boat and in case of sale of the VHF radio. It should also be underlined that, in order to be in order, the licence to operate VHF equipment must be updated also in case of change of residence (if this is established in a different region).

There are many people who wonder about the real need for these documents. Why is it necessary to have a licence in order to use a VHF on a boat? What is the point of requesting a licence, without, moreover, there being an exam to take? In reality, the answer is quite simple, if one only puts oneself in the perspective of the legislator. The radio transmitter on board is in fact a real radio station, capable therefore of transmitting its message on several devices. As such, each VHF device is distinguished by a precise International Call Sign, that is, a long sequence of numbers opened by the letters 'IZ' or 'IY'. IN .

What is the maximum distance to communicate with a VHF radio?

In many cases one tends to think that the range of a VHF radio is an absolute value. In fact, the result depends largely on the height at which the transmitter and receiver antennas are placed. An example? It is possible to communicate between a boat and a coastal station 60 miles away; the same boat, with the same VHF radio, will not be able to do the same with another boat. The same vessel, with the same VHF radio, will not be able to communicate with another vessel for more than 15 or 10 miles.

In fact, there are two factors to take into consideration: on one hand, there is the power of the nautical VHF equipment; on the other hand, there is the curvature of the earth. In fact, VHF waves propagate in a straight line and manage to connect all visible points, that is, those that are not cut off by the horizon line. If two antennas 'see each other', then communication is possible. If not, every connection is destined to fail. From this, we understand that the range of VHF radios increases together with the height at which the antenna is positioned: sailing boats, in this case, are advantaged, since they can install the antennae on the masthead. Motor boats, on the other hand, can use the flying bridge.

Let's take a look at some concrete values, as an example. On average, a fixed VHF boasts a range of about 15 miles, while a portable VHF lowers this range to about 10 miles. In any case, as anticipated, these values can vary according to antenna height, atmospheric agents and geographical position.

Looking at the actual power of VHF radios we find that portable models usually boast a power of 4, 5 or 6 Watts, while the fixed type boasts 25 Watts. Such a deployment of power, however, is in most cases useless, disturbing and counter-productive. For this reason, when the communication to be made is short-range, it is possible to lower the power to 1 Watt through the special button, present in both types of model. What are the advantages of this operation? Very simple: in this way, less energy is used, to the benefit of the battery; communications remain more confidential, reaching fewer receivers; interference is not created unnecessarily, which can even seriously disturb other nautical VHFs.

VHF for boats: guide for use

But how is a nautical VHF used in practice? Well, in portable models as in fixed ones, there is a more or less high series of buttons. In practice, however, the fundamental buttons are 4-5. First of all, obviously, the on/off button. Another essential button is the one for the transmission, that is to say that you can speak and send your message into the ether. There is then the channel selector, to communicate within a given frequency, and the noise filter, that is the command to adjust.

Finally, there is the possibility to communicate in a unidirectional or bidirectional way, thus setting the simplex or duplex mode. What does this mean? In simplex mode, the frequency used will be only one: this means that transmission and reception will take place on the same line, and therefore it will not be possible to do the two things at the same time, with the need to leave the line free to receive messages from outside. In this case, at the end of your message - to make the other operator understand that you have finished your message - you generally use the word 'pass', so as to make them understand that the line is free. To confirm the reception you use the word 'received', and to close the communication you use the classic formula 'over and out'.

Less complicated and simpler is the duplex communication mode: in this case, in fact, the two operators can transmit simultaneously without any type of problem. The VHF radio, in this mode, works in every way like a normal telephone.

Which channels to use?

When talking about marine VHF, we are talking about channels and not frequencies because, as a direct consequence of international agreements regarding nautical communications, it was decided to divide the various frequencies into specific channels to be used. To give an example, channel 16 will in all cases have a frequency of 156.8 mHz. But which channels should be used? Each use has a different answer.

For optimal use of the VHF equipment, the radio should always be turned on and tuned to channel 16, which is dedicated to emergency situations only - this means that to make a distress call you must use this specific channel. In a normal situation, therefore, a VHF radio should be tuned to channel 16 in listening mode. And if this is an option to be taken into high consideration in the open sea, it becomes a real necessity when entering and leaving a port, where every communication becomes precious.

Channel 16, by the way, also carries all the crucial navigational warnings and weather reports. But that's not all: as a rule, during the first few minutes of every half hour it is necessary to maintain total radio silence on this channel, because it is precisely in that period that any emergency or safety signals are concentrated.

Channel 16, therefore, is certainly the channel not to be forgotten when talking about communications at a nautical level. Channels 6, 8, 72 and 77 are generally used for normal communication between one boat and another, while certain other channels are reserved. Channel 9, for example, is assigned to Port Authorities, while channel 70 is reserved for DSC. But what is DSC in the world of VHF boats?

What is DSC, and how is it used?

DSC is an acronym, and stands for Digital Selective Calling. This button - sometimes also called Distress, typically red - is present on many of the modern VHF radios on sale, and allows you to immediately and automatically forward a distress message. Pressing this button sets in motion a digital mechanism to communicate not only the distress call, but also the coordinates of our position.

As anticipated, DSC works on channel 70: here no other type of communication can exist, and therefore interference is reduced, even more than with the above mentioned channel 16. First of all, the communication of the emergency situation, and therefore the request for help and the sending of coordinates, are instantaneous, without wasting even one second too many for sailors in difficulty; moreover, the message in digital form has a greater coverage.

But what does DSC transmit? What information is actually being sent? In extreme synthesis, among the data sent by pressing the Distress key there is the position of the ship, which is provided by the GPS interfaced to the device (otherwise it must be typed manually); the MMSI of the boat, that is an identification code that allows to recognize the type of boat; the moment in which the position of the boat was updated.

To date, DSC is not required by law. And that's not all: in many cases, sailors equipped with this function do not know that, in order to actually use this service, it is necessary to enter the MMSI code, which, however, must be expressly requested from the Ministry of Economic Development. Not having it - and not knowing it - means finding oneself wanting to use DSC in case of emergency only to be asked - by one's own VHF radio - to insert the code.

We have shed some light on some of the main questions that are common to those who want to purchase a VHF radio for their boat: fixed or portable, with or without Distress, on this page you can purchase the VHF that best meets your needs!

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