Ormskirk Sub~Aqua Club

BSAC Branch 879

Dive Safe!!!

Why have a radio to keep in contact with land?

Coastguard VHF Radio operator at Liverpool Coastguard Station at Crosby.

 

Some boat users go out with just a mobile, but no radio.  This is very life threatening when out at sea.  No matter how far out.   Today's boaters are faced with many choices for ship-to-ship and ship-to-shore communications. VHFs, cell phones, Family Radio Service radios, CB radios, Single Sidebands, and satellite communications are among the myriad of choices available.  So why get VHF?

VHF Radio has been the principal form of ship to ship and ship to shore communication for many years and still is one of the most used systems at sea by small boats.   They are essential for emergency situations, and are monitored 24 hours a day by the Coast Guard in coastal and inland waters.  

On a phone you do not get the information that is sent over the radio.  If you need to contact land or another ship, you just have a phone...  do you  know the number?  That is if the ship has one that is! Coverage of the phone network is not designed for the sea.  VHF Radio is and masts have been erected all around the coast to pick you up!

Why not get a CB Radios?     Don't like water as they are not designed for boats.  Channel noise and station traffic are sometimes heavy, and the Coast Guard doesn't monitor the emergency channel and illegal in some countries and give out information.

Satellite Communications?  Coast Guard doesn't monitor and give out information. 

Family Radios (License Free Radios)?  Coast Guard doesn't monitor and very short range.   Channels can be overloaded and have kids playing on them.

So, Modern Marine VHF transceivers?  Well they are well constructed communications devices that are an indispensable aid to safety and navigation.   Reliance on a cell phone to replace a VHF radio is not a good idea!  Other forms also have big down falls.  If going out to sea ALWAYS have a VHF RADIO! 

Most important thing is, if you are going out to sea, learn how to use the VHF Radio and get a license. Do not for get to do a radio check, but be warned, only operate under the Maritime Radio Laws, again do a VHF Marine Radio course to learn them.

Facts about VHF Radio!

VHF (Very High Frequency), refers to the frequency spectrum, defined as the part of the electromagnetic spectrum, which includes any radiation with a wavelength between 1 and 10 metres and a frequency between 30 and 300 megahertz. VHF signals are widely employed for television and radio transmissions due to clarity and range. Of transmissions using this form of wave. 

When doing VHF courses they instructor will talk about, short range, Line-Of-Site transitions, this refers to themast and if it can be seen by the other mast you are trying to contact.  As VHF electromagnetic waves, unlike longer electromagnetic waves, are not strongly reflected from the atmosphere.  This is a problem that you must take into account when at sea, as they do not carry beyond the horizon. This limits the range of transmitters to the height of the mast transmitting and receiving the waves. 

What are the operational range Maritime VHF equipments?  Maritime VHF equipments operate in the 156 - 174 MHz range. 

So why use VHF? It’s clarity, range improving as the technology progressed. VHF waves are especially suited to maritime, air communications, TV etc. because their reception is not impaired by random electromagnetic noise ("static") of longer wavelengths. Because of their limited transmission range, transmitters several hundred miles can use VHF signals of the same frequency apart without interfering with one another. 

What are DSC and GDSS? Now major advances in Radio technology have created the Digital Selective Calling system (DSC), part of the Global Maritime Distress and Safety System (GMDSS).  GMDSS requirements specify channels and that shall be used for specific purposes such as Distress calling, intership and Digital Selective Calling (DSC). It was first produced for the world's Merchant Shipping fleets. The DSC system is intended to make distress calling faster and more accurate and allow the user to call up individual ships and coast stations. As with most new technology, initial systems were costly and large, with two units needed to handle the VHF and DSC functions. Now the systems have been made smaller and this is now becoming the practical for operation on small vessels. This system will have a considerable impact on the way safety at sea is co-ordinated in the future. 

What is VHF channel 16 (156.800 TX/RX)?  It is the international distress and calling frequency.

Distress Calls? If in a distress situation, when in grave or imminent danger, use the distress call Mayday on Channel 16.  If in an urgency situation, when no imminent danger to life exists (eg if broken down and drifting), use the urgency call Pan Pan on VHF channel 16. For non-urgent safety messages call the Coastguard on VHF channel 67, often referred to as Six Seven. 

What is a Working Channel? A working channel is one that communications are diverted to, like 67, to free up other channels for more important traffic.