| Types of VHF sets: | | | | station. |
| Non-DSC sets | | | | When talking from yacht to yacht expect a range |
| Non-DSC VHF sets on yachts and motorboats will | | | | of 10 to l5 miles with aerials fitted at the tops of |
| still continue to work, will still be legal to use and | | | | the masts. Those commonly fitted to yachts are |
| certificate holders do not need to do a conversion | | | | known as 'unity gain' aerials. They are made of |
| course until they choose to upgrade. After 2005 | | | | thin wire and often have wind instruments |
| Coastguards will cease to monitor Channel 16 in | | | | attached. They are recommended because, |
| the way that they do now, that is with a | | | | although the range is not as good as the taller |
| dedicated officer on headset watch 24 hours a | | | | rigid aerials used on motorboats, they cope better |
| day, but they will continue to have a loudspeaker | | | | with the heeling effect often experienced on |
| watch on channel 16 in the operations room. | | | | yachts! The better range of a 'high gain' motor |
| Increasingly the boat without VHF DSC radio will | | | | cruiser aerial is only achieved if it is mounted |
| be at a disadvantage. | | | | vertically. |
| A transportable set is an invaluable second radio | | | | It should be possible to talk to a Coastguard |
| for use in an emergency when it can be taken | | | | station from 30 to 40 miles offshore because of |
| into a life raft or used on deck to communicate in | | | | the height of their aerial. |
| a rescue situation. It is useful for safety reasons | | | | Transmitting range is also affected by the |
| in a tender when going ashore or in a safety boat | | | | transmitting power of the set. The maximum |
| when organising dinghy sailing events. A portable | | | | power allowed is 25 watts. There is also a low |
| set is a good buy for non-boat owners who | | | | power setting, which reduces the transmitting |
| charter or who go afloat occasionally. They have | | | | power to 1 watt. This should be used for all short |
| a limited range but do require licensing and | | | | range routine communications. You might think |
| certification. Portable sets with a very limited DSC | | | | that it is always a good idea to broadcast your |
| facility are available. They are intended as an | | | | signal as far as possible. This it not so. Remember |
| addition to a full VHF DSC set, not as a substitute. | | | | that each channel can only be used for one |
| Note that the portable set covered by a ship's | | | | transmission at a time. Powerful signals cause |
| radio licence can only be used on the vessel | | | | more inference to other radio users. If you are |
| covered by the licence or by its tender(s). It is | | | | calling another craft nearby or a marina, use low |
| illegal to use the portable ashore. | | | | power. Try to use low power for all routine |
| VHF DSC radio sets | | | | communications. The use of low power does not |
| From 2001 all new non-portable radios sold must | | | | change the receiving range of the set. |
| be VHF-DSC or be capable of being converted to | | | | A portable VHF set has yet another type of |
| DSC by the addition of an extra 'black box'. | | | | aerial. This is flexible and will operate at a wider |
| These are called DSC Controllers. It will provide | | | | range of angles. The low aerial height and a |
| the digital selective calling (DSC) facility which is | | | | maximum power output of 5 watts reduces the |
| the special feature of the new type of set. What | | | | range of transmission of these sets. Between |
| this does is to send, on channel 70, a burst of | | | | portable radios the range can be up to 5 miles, |
| digital signals in a code to 'call up' another DSC set. | | | | increasing to 10 miles to a Coastguard station, if |
| This call can be directed at an individual, using their | | | | there is no land in the way! Remember, with |
| MMSI, a group of boats or 'all stations' in an | | | | portable radios there is always the risk that the |
| emergency. Once the link has been established by | | | | battery will go flat. |
| the digital 'call', normal voice transmission will be | | | | The information about ranges of transmissions is |
| used. The DSC is essentially a new method of | | | | for average conditions and good circumstances. |
| establishing communications, more reliably than | | | | Ranges can be influenced by:o Atmospheric |
| was possible before. The digital signals are of high | | | | conditions, especially high pressure, can increase |
| radio quality and rapid, the alert taking just 0.5 | | | | the range and cause interference from distant |
| seconds. It can be used in both routine and | | | | stations.o Land. Boats operating near land may |
| distress situations. | | | | have poor reception with signals being blocked by |
| There are different classes of controller with | | | | hills or buildings.o Incorrect installation of the aerial, |
| varying levels of capability for use in different | | | | or damage to the coaxial cable connecting the |
| types of vessel. | | | | aerial to the set, can give poor reception.o The |
| The Class D controller is the one designed for use | | | | proximity of other electronic equipment can cause |
| with VHF on yachts and motorboats who make | | | | interference. |
| passages within VHF range of the coast. Fitting | | | | For these reasons it is best to have the fitting |
| one of these is not compulsory on private boats. | | | | done, or at least checked, by a professional |
| On small boats used at sea commercially, sea | | | | electronics engineer. |
| school boats for example, it may become a | | | | A portable radio has a range of 5 miles to |
| requirement. This will be to the great advantage | | | | another portable, 10 miles to a Coastguard |
| of their students who will be able to see the sets | | | | Station. |
| in use and appreciate their advantages. | | | | All distress calls should be transmitted on high |
| Other controllers for VHF DSC are available to | | | | power. |
| meet the requirements of ships. These include | | | | Many yachts carry emergency VHF aerials in case |
| Class A and B Controllers, which have enhanced | | | | of dismasting, which is a very good idea, but |
| capabilities. | | | | failure of the electrical supply is a more frequent |
| What is the range of the set? | | | | problem! The emergency aerial has a plug |
| Those sailing across an ocean, or even the Bay of | | | | attached to connect it to the back of the set. For |
| Biscay, need radios that transmit over vast | | | | maximum range, situate the aerial as high as |
| distances. Licensing arrangements are different | | | | possible, but realistically expect a greatly reduced |
| too. | | | | range. When the mast is lost, many people are |
| The range of transmission of VHF radio | | | | surprised to hear the radio apparently still working. |
| telephones is limited by a number of factors. The | | | | This is because the co-axial cable is acting as an |
| height of the aerial is very significant as the | | | | aerial over a short range, but transmitting without |
| propagation of the radio waves is only slightly | | | | an aerial will damage the set permanently. |
| more than 'line of sight'. This includes the aerial | | | | A portable radio could be useful under these |
| height of both the transmitting and the receiving | | | | circumstances! |