How do marine vhf radios work

Channel 06 - Ship-to-ship safety messages, and communication with search and rescue and Coast Guard vessels and aircraft. Channel 13 - Ship to bridge or lock master, ship to tender calls. Commercial vessel use primarily. One watt of power, used for close in communicating. Channel 22 - Used to speak with Coast Guard after initial contact on Channel Coast Guard also makes safety broadcasts on this channel.

Channel 70 - Digital Selective Calling. Those vessels with DSC radios should use this channel for distress and calling channel instead of Channel 68, 69, 71, and 72 - Used solely for communications between vessels.

Handy Tips At the start of a trip, always power on your radio and begin with a radio check. Radio checks are allowed on channel To perform a radio check, say "radio check" and your location. For example: "Radio check, Newport Harbor. All fixed-mount marine radios can transmit at either 25 watts or 1 watt. The maximum power from a handheld is typically 5 watts or 1 watt.

With either type, if your radio contact is nearby, set the power setting to low 1 watt to reduce the distance the signal carries beyond your target. Show others on-board how to use the radio. In an emergency, if something happens to you make sure they know how to make a call. Watch your language. Not only is profanity over the air against the law, it will be particularly offensive to other boaters with children aboard.

To adjust the radio's speaker volume , turn on the radio and untune the squelch by turning the dial until static is heard over the speaker. Adjust the volume. Then re-tune Squelch just enough to make the static stop for most sensitive reception. Always monitor channel 16 , an international standard for distress and hailing. All mariners are required to monitor this channel whenever their boat is in motion.

If you are monitoring a second channel, you can use the scan button to toggle between channel 16 and the other channel. The monitor function will automatically switch to whichever channel transmission is heard. Don't tie up a channel. A radio conversation ties up the channel you are using. No one else within a 25 to 30 mile radius can use it until you sign off. There are only five channels available for pleasure boat-to-boat communication.

Please be considerate. The five channels designated for non-commercial ship-to-ship communications are 68, 69, 71, 72, and 78A. Channel 9 used to be in this group but has been re-designated as an alternate calling but not distress channel. You may hail another vessel on channel 16 and then ask them to switch to another channel. However, sometimes when you switch to a working channel, you find it occupied. In that case, check the other four to find an empty one, then go back to 16 and say, "Your name, their name, channel.

For example: "Cowboy. This is Tambourine. Seven one. Channel 13 is for navigational use between vessels. Large vessels in close proximity announce their intentions to one another on this channel. This is also the primary channel used at bridges and locks. Use this channel to announce your arrival to a bridge or lock tender, or to communicate with a nearby ship or other large vessel.

You do not need to call on Channel 16 first. This is a good channel to listen to in periods of poor visibility so that you can communicate with ferries, freighters, and other large vessels.

You must use the low power on your radio when broadcasting on Channel Although you may have many other channels on your radio, each of them is restricted to specific uses. How do I use it? The standard procedure for a non-emergency call such as calling another vessel, marina, or restaurant to ask where to tie up for dinner, is as follows: Call the vessel, marina or restaurant on Channel 9 in the following manner.

Name of station being called, spoken three times. Name of your vessel spoken once. The word " OVER ". Then you wait for the station being called to answer. Their answer should be in the same manner as your call. Once answered you should suggest a specific working channel to carry on your conversation. Wait for reply or confirmation from the station being called, switch to the working channel and repeat the process. When done speaking and leaving a specific channel use the word " OUT " at the end.

What about in an emergency situation like mayday? Transmit in this order: Tune your radio to Channel Name of vessel in distress spoken three times.

Give position of vessel by latitude or longitude or by bearing true or magnetic, state which and distance to a well-known landmark such as a navigational aid or small island, or in any terms which will assist a responding station in locating the vessel in distress.

Include any information on vessel movement such as course, speed and destination. Provide nature of distress sinking, fire etc. If you hear a distress call What to do if no one responds to your distress call Tune your HF radiotelephone to an HF channel guarded by the Coast Guard, and repeat your mayday call. A ship or shore unit wishing to call a boater would do so on channel 9, and anyone boaters included wishing to call a commercial ship or shore activity would continue to do so on channel Recreational boaters would continue to call the Coast Guard and any commercial facility on channel The purpose of the FCC regulation was to relieve congestion on VHF channel 16, the distress, safety and calling frequency.

FCC regulations require boaters having VHF radios to maintain a watch on either VHF channel 9 or channel 16, whenever the radio is turned on and not communicating with another station.

Since the Coast Guard generally does not have the capability of announcing an urgent marine information broadcast or weather warning on channel 9, use of channel 9 is optional. We recommend boaters normally keep tuned to and use channel 16 in those waters unless otherwise notified by the Coast Guard. Procedure for Calling A Ship by Radio You may use channel 16 to call a ship or shore station, but if you do so, you must, must be brief!

No other uses are permitted. Many vessels are now equipped with DSC capability and are using channel 70 for this purpose. It is essential that this channel be protected. Storm Warnings? I will offer up only 2 that should provide you with a reasonable guide of what theoretical range you can expect from your particular installation. The fact is that the differences in the answers derived from either method are so small that it is unlikely to make much difference in the scheme of things.

For the conservatives among us this first formula does not take into account any bending of the radio waves and equates to the distance to the visible horizon. Where D is the distance to the horizon in NM; r o is the mean radius of the earth If you are looking to solve the distance in statute miles or kilometers you can use these formulas:.

The radio horizon is probably a truer representation of the maximum range of your VHF radio. But wait a minute, I talk regularly with other vessels at much longer distances than 10 NM, how is that? You have to keep in mind whenever you are communicating with another station; you must factor in their antenna height as well and add this to your vhf radio range.

You will then have the distance that you can expect to be able to initiate communications. Their radio range would calculate out to 8. Combine this with yours and you would likely be able to establish communications at almost So, what does all of this mean?