Marine Radios & Antennas
VHF Radios & Types
A VHF radio's communication range with another unit will depend primarily on their antennas but is generally between 5 miles to as much as 25 miles or more, depending on the antennas' line of sight propagation.
Close-distance communications between boaters and the ability to radio for assistance when necessary are essential elements of enjoying safe boating, many of us rely primarily on our VHF radios to accomplish both.
There are two types of VHF radios: Handheld and fixed-mount.
Most boaters install fixed mount units unless the boat is small, usually less than 16 feet, or the boat is a tender to a larger vessel. Very large vessels and those with multiple tenders often carry several handheld VHF radios. Handhelds allow the crew to talk to the mothership from a tender, to communicate with each other and can serve as a backup radio if the fixed-mount unit fails.
Lowrance "Link-5" Marine RadioA highly functional VHF
The new Link-5 Lowrance - It is waterproof and robust, and incorporates the last functions a VHF of Class D global use.
Lowrance launches the Link-5, a fixed VHF with DSC. Now you can noted for its value for money.
The Link-5 Marine Radio It incorporates the latest features of a VHF, is a Class D for global use, and offers high performance level.
Your microphone has six hotkeys to more easily handle and built-in speaker, clear sound even with the typical background noise associated navigation. Designed for simple use of DSC Class D, rotary knob of the new Link-5 It changes the channel surfing the menus and adjust settings clear and intuitive.
The latitude and longitude GPS are presented on a screen LCD 2.6 x 4.6 cm with adjustable backlight. All international channels, the system It offers quick access to the DSC functions. It incorporates an extra key great for Channel 16, buttons specific volume and squelch.
The housing is waterproof and robust, and has been designed to complement the color and style new screens © HDS Gen2.
Equipped with memory retention, this VHF radio stores up to 10 calls DSC distress calls and 20 individual Dual.
Control keys DSC include 16/9 (priority) 3CH / + / - to quickly change channels, CALL, EXIT, SCAN and MENU.
Other Control services offered are rotary volume with on / off, all channels and priority scan.
Channel 20 names MMS1 user programmable channels meteorology tone alert 1050 Hz and a second receiver for channel 70.
Power 25/1 transmission watts , the Link-5 It includes a flush mounting kit, cables for external speakers 4 watts and an optional bracket steel / nylon steel antenna Fiberglass 2.4 m and 1 m.
Besides the two-year statutory warranty, extension offers many years of coverage by Advantage Program.
Learn more: Lowrance VHF - http://www.lowrance.com/en-US/Products/VHF-AIS/Link-5-DSC-VHF-en-us.aspx
Fixed-Mount VHF Radios
Fixed-mount radio units can be either bracket or flush mounted. On photo above: Simrad VHF Radio - RS35 (simrad-yachting.com)
Advantages and Disadvantages
The radio can run off the ship's battery bank. An external antenna, mounted as high as possible, will give you greater range. But If you have more than one helm or a cockpit and navigation station, you may want two or more radios.
Handheld VHF Radios - Advantages and Disadvantages
This New Cobra® (on photo below) is the VHF radio for your on-the-water lifestyle You can select between 1-, 3- and 6-watt output power and seceives all weather(NOAA) channels.
These are independent of the boat's electrical system Handhelds are portable; they can be used away from the mothership, be taken home for safekeeping or used at a second helm station or cockpit Can be used in smaller boats that have no "house" battery bank.
But limited range of 3 to 5 miles and lower transmit power. Battery life is limited and requires charging.
VHF Radio Features
Audio Output Power Rating
When reviewing the manufacturer's specifications, note that a higher power rating, or audio output rating, does not mean longer transmission range. A high power rating creates a stronger, clearer signal, which may allow you to be heard from longer distances but has no bearing on how well you receive transmissions. Most fixed-mount VHF radios have both a 25 watt and One watt power rating. The lower power is used for nearby radio communications. Handheld units have a maximum 5 watt high power rating and some will also have a low power rating of 1 watt.
A scan mode allows you to monitor radio traffic, and some manufacturers offer a variety of modes. The radio will scan the channels and stop on an active channel, moving on to the next channel when conversation stops on the last channel.
There are several different scan modes:
All-channel scan does just exactly that listens to every active channel in succession.
Programmable/Tag scanning allows you to select the channels you want to scan. This scan mode functions just like your car radio; select the channel you want to monitor, press the "memory" key and the channel is stored in memory. To deselect the channel from memory, simply press the memory key again. You can do this with as many channels as you want and change them at any time.
Seek also functions just like your car radio, it stops on an active channel for only a few seconds then moves on to the next.
Priority scanning overrides all other channels returning to Channel 16 when 16 is active. If there's a lot of hailing traffic on 16 your radio will remain on 16 most of the time.
Dual Watch scanning allows you to monitor both Channel 16 and one other channel that you select. If another boat hails you on 16, you won't miss the call if you're listening to traffic on another channel.
Tri Watch scanning monitors Channel 16, the USCG emergency channel, and two other channels of your choice.
There are currently two methods of selecting channels on VHF radios: rotary knob and keypad. All radios have a "Channel 16" button that, when pressed, takes you immediately to Channel 16. Some fixed-mount models have an additional channel selection function on the microphone.
To change channels with a rotary knob, a dial is turned until you
reach the desired channel, this method for changing channels is
Keypads have one "up" and one "down" key. Pressing either one gets you to the channel you want.
With this feature, the radio detects a unique signal from NOAA (National Oceanographic and Atmospheric Administration), then alerts you with a particular tone to important weather notices. Some radios will automatically tune to the weather channel issuing the broadcast, while other radios require you to manually tune the radio to the weather channel after the alert tone has been received.
Digital Selective Calling (DSC)
The FCC requires that all new fixed-mount VHF radios be equipped with DSC, part of the Global Marine Distress Signaling System (GMDSS). DSC-enabled radios send an encoded distress signal that's picked up by nearby vessels when the DSC function is activated. DSC transmissions are sent and received on Channel 70 (156.525MHz) which is reserved for digital transmissions. Ownership of a DSC VHF radio requires that you obtain a Maritime Mobile Service Identity (MMSI) number. The FCCD does not require
DSC on handheld VHFs, although some manufacturers are including the feature.
There are several classes of DSC but Classes D and E are currently classified for vessels not required by law to conform to GMDSS standards, such as recreational vessels.
Class D has the least DSC capability for recreational VHF marine radios.
DSC Class D capabilities include distress call, all-ships call, individual station call, use of distress (urgency, safety and routine priorities), nature of distress, distress coordinates, time for last position, type of subsequent communications, radio VHF channel, display, receive distress relay and distress acknowledgment calls, and alarm.
Class E has the least DSC capability for recreational MF/HF marine radios. The minimum capabilities are the same as for Class D, except radio VHF channel reads radio channel or frequency.
A distress call will include the MMSI number and a specified voice channel to be used when the call is acknowledged and includes the nature of the distress. The lat/lon coordinates of a distressed vessel, can be manually entered or automatically supplied by interfacing a GPS or Loran to the VHF, so rescuers can pinpoint a distress vessel's location and know where to begin the search.
The Coast Guard currently monitors both MF/HF marine radio frequency 2182 kHz as well as VHF channel 16 for emergencies.
Some radios are equipped with public address (PA marine and offshore system), hailers, listen-back and foghorn capabilities, all of which require an external weatherproof speaker.
The PA and hailer functions allow you to communicate with crewmembers on the foredeck, line handlers on the dock, lock tenders or other boats. The primary difference between the two is the output power. The PA is usually less than 10 watts and the hailer is 10 watts or more. Listen-back amplifies sound by turning your external speaker into a microphone. The foghorn feature allows you to automatically or manually broadcast a legally required signal for operating in reduced visibility.
to buy Radio
If you plan to buy, purchase a handheld radio with long-life batteries,
at least 8 hours on standby.
Whether you buy a fixed-mount or handheld radio or both, select a radio that is easy or intuitive to use, accompanied by a manual that is easy to read and understand.
If you purchase a radio that is scramble-enabled to keep other boaters from eavesdropping on your conversations, other radios that you communicate with must also be scramble-enabled.
All users must know the scramble code that's in use. If you have difficulty hearing or operate in a noisy environment such as from an open fishing boat, choose a radio with larger speakers for greater clarity, or add speaker extensions to bring the transmitted sound closer to your ears.
A waterproof radio should be considered if it will be mounted in an exposed location. Know what the manufacturer's specifications are regarding the unit's ability to withstand UV exposure and what it's high and low temperature ratings are. If the unit is to be mounted in an enclosed cabin, a weather-resistant radio is fine.
CB Radio Antennas
CB antennas are more frequently found on cars and trucks, but CB'ers will also want to operate from their boats. This 11 meter band (27 MHz) is a very popular method of communication with land-based repeater stations being found in most cities.
The authorized frequency ranges for CB radio are from 26.965 to 27.405 MHz and operates within these frequencies with over 40 channels. When selecting an antenna, choose one that has an SWR of 1.5:1 or less in the mid-range of these 40 channels, either 19 or 20.
Since most CB radio jacks are intended for a 50 Ohm load, your antenna should have no more than 50 Ohm antenna impedance and a 50 Ohm coaxial cable attached to it. The point is to match your radio's intended load to your antenna's impedance, otherwise maximum power is not realized by your unit. Match your radio's RF output power to the antenna's maximum input power and provide for a 90-95% efficiency rate.
In other words, if your radio's RF output power is 50 watts, purchase an antenna with a maximum input rating of 100 watts to avoid a loss of power through the antenna.
Most marine CB antennas will have a gain rating of zero, also referred to in some manufacturer specifications as "unity". This is good for sailboat owners but if you own a power boat, you might want to consider a longer antenna with a higher dB gain. Your CB antenna should also have a DC ground. A good one - the Professional Mobile CB Radio come from Uniden.
AM/FM Radio Antennas
Having a good antenna to receive your favorite stations when you want news or music is a necessity.
AM radio waves travel both on the ground and through the air, and as a result are prone to interference by other radio stations, lightning storms, and nightfall. While radio waves travel in straight lines, during the day an outlying AM station's signal can reflect off the ionosphere and skip over areas that usually receive the signal.
The best FM reception will be an unobstructed, line-of-sight path to a transmitting antenna. The farther the signal reaches, the weaker it gets, especially when out of line-of-sight. When there are reflecting surfaces such as tall buildings or mountains near your receiving antenna, FM radio waves are subject to a disturbance known as multi-path which can cancel out the original broadcast signal at select points. A longer, higher antenna produces better reception and antenna length can range from 1-8'.
Sailboat owners have an advantage over powerboat owners because they're able to mount the AM/FM antenna high on the top of the mast. Powerboats ususally have longer antennas for adequately receiving AM/FM station signals.
This Shakespeare 3' fiberglass AM/FM Marine antenna (on photo below) is designed with a 1"-14 thread nylon ferrule for use with standard marine mounts.
An AM/FM antenna should cover the frequencies of 550-1600 KHz for the AM bands and 88-108 MHz for the FM bands. With the majority of these antennas, the coaxial cable is connected inside the antenna by the manufacturer or screws to the ferrule (base). A male plug should also be provided at the other end of the cable for connecting into the back of the radio. Since these connections are, for the most part, made by the manufacturer there are few options or considerations to be made when buying and AM/FM antenna.