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ContinuousWave: Small Boat Electrical
VHF Marine Band Radio for Connecting to Chart Plotter
|Author||Topic: VHF Marine Band Radio for Connecting to Chart Plotter|
posted 01-26-2015 07:32 PM ET (US)
Which VHF radio would be the easiest to connect to my Garmin 431s GPS? I'm not planning any long runs offshore but want something reliable. I'm considering either Standard Horizon Eclipse GX1200 VHF, Standard Horizon GX1600 Explorer VHF or an Icom M412. Is one unit better then the other? Or at that price point, are they much the same?
posted 01-27-2015 09:48 AM ET (US)
When connecting a VHF Marine Band radio and a chart plotter, there are typically two connections:
--CHART PLOTTER to RADIO: this connection sends position data to the radio from the chart plotter, which typically has a GNSS receiver, and
--RADIO to CHART PLOTTER: this connection sends DSC data received by the radio to the chart plotter, which will typically display that information in some manner on the chart plotter
There are two general methods for making these interconnections:
--using NMEA-0183 port-to-port wired connections, or
--using NMEA-2000 networked connections.
If both the chart plotter and the radio have NMEA-2000 networking, interconnecting them with that method is the easiest. The network connection transports data in both directions between the devices.
If NMEA-2000 is not used, one must interconnect the devices with NMEA-0183. This can often be a challenge for boaters, but, with a few minutes of study and with a understanding of the concept, it can be done. With NMEA-0183 the connections are not bi-directional. A connection must be established in each direction between radio and chart plotter. Also, with NMEA-0183 the electrical signals are usually just provided on loose wires, without connectors, so some sort of connection arrangement must be invented by the user and provided to make the actual connections.
Most lower-price-tier VHF Marine Band radios do not have NMEA-2000 network connections. Many chart plotters, but not all, have NMEA-2000 connections. Just about every radio and every chart plotter will have NMEA-0183 connections.
If you want to use NMEA-2000, the best radio choice in terms of price will be the Lowrance LINK-8. If you want the least hassle, get a VHF Marine Band radio with its own GNSS receiver; no interconnection is needed for the position data to the radio. You can still connect the radio to the chart plotter for display of DSC targets if desired.
posted 01-27-2015 10:07 AM ET (US)
In terms of the two brands, ICOM and STANDARD-HORIZON, as choices for a VHF Marine Band radio, they are both good brands, and I would generally prefer them to other brands on the basis that those two companies specialize in communication radios.
On my own boat I have a Standard-Horizon radio. I tend to prefer Standard-Horizon radios on the following basis:
--the user interface of the Standard-Horizon radio is generally well organized in an hierarchical manner, and the operator can usually intuit the layout and organization without having to resort to reference to a manual; in other words, they are easy to operate;
--Standard-Horizon seems to be very interested in making sure their radios are completely qualified to digital selective calling standards and comply with them fully. Historically they have been the first manufacturer to offer certain features, and they tend to implement those features very well;
--Standard-Horizon provides very good technical support, with friendly people, that are easy to reach via email or telephone, and they actually participate in many on-line forums to help their users. You will see them answering questions about their products in boating forums all the time. I never see this from other companies making radios.
--Standard-Horizon radios are seen in use on government boats when the radio is specified as a commercial-off-the-shelf or COTS radio. That is a good endorsement, although those radios are usually the top-tier models, not the under-$200 models;
--Standard-Horizon has a nice repair policy with a flat rate repair charge; they can actually fix your radio instead of making you discard it and buy a new one. (Of course, for the least-expensive radios this may not be a consideration. Maybe it would be more cost effective to just replace a broken inexpensive radio with a new one.)
--Standard-Horizon radios tend to have very good transmitter modulation quality, at least based on what I hear in-use on the VHF Marine Band, and
--Standard-Horizon radios provide their NMEA-0183 interface with the standard, recommended, ballanced RS-422-type electrical interface, making them very easy to interface; other brands often use single-ended non-standard interfaces which cause difficulties and problems in interfacing.
At the moment, the only drawback to a Standard-Horizon radio is their lack of NMEA-2000 interface. ICOM does have a radio with NMEA-2000, but it is a rather expensive model.
posted 01-27-2015 11:08 AM ET (US)
Regarding having NMEA-2000 in a VHF Marine Band radio, it is a nice feature, but the lack of it does not mean the radio is useless or obsolete. On a boat, particularly on a small boat, the VHF Marine Band radio is really going to interface electronically with one other device, the chart plotter. It is unlikely that the radio needs data from or could send data to any other devices that might be found on a small boat. The radio and the chart plotter can interconnect with NMEA-0183 wiring.
Perhaps the biggest obstacle for NMEA-0183 interfacing occurs if the boat operator wants the radio to be removed from the boat after every use. A connector will be required for the NMEA-0183 cables. Most radios provide the NMEA-0183 wiring as a loose pigtail of conductors at the end of a short cable. The installer has to invent some sort of connector arrangement, if the radio must be easily removed from the boat. Because NMEA-2000 wiring is usually pre-wired with connectors, that gives it an advantage.
If the lack of a connector can be overcome, the NMEA-0183 interface wiring is not particularly difficult to accomplish. Once the interface has been correctly wired, and the connection is made via a connector, there is no more fuss with NMEA-0183 than with NMEA-2000.
I do expect that more radios will appear on the market with NMEA-2000 interfaces, and I would hope that the inclusion of NMEA-2000 will not be limited to only the most-expensive models. The Lowrance LINK-8 is a very good example of a moderately priced radio with NMEA-2000. It should be possible for others, like ICOM and STANDARD-HORIZON, to follow that lead--at least I hope they will. Unless you need to buy the radio today, it might be prudent to wait for at least a month or two in order to see what new products might show up at the Miami International Boat Show for 2105.
posted 01-28-2015 09:27 AM ET (US)
The ICOM 506 model is both NMEA-0183 [and NMEA-2000] compliant. I have a one installed on my 210 Ventura. The ICOM 506 works great and was picked up by my Garmin 741 and Garmin 840 via [NMEA-2000] without problems.
In this picture you can see the [NMEA-2000] connection from the radio to the N2k backbone.
Once connected to the [NMEA-2000] backbone you get these displays on my Garmins.
posted 01-28-2015 10:50 AM ET (US)
For more information about the ICOM IC-M506, see
The price of the ICOM IC-M506 is around $600 MSRP. It is a nice radio, but that is a lot of cost to pay for the convenience of NMEA-2000. In contrast, the LINK-8 is about half the price and includes an AIS receiver. You can get an AIS receiver on the ICOM IC-M605, but it adds more to the price.
As long as we have shifted focus to radios with NMEA-2000, also consider the new RAYMARINE radios with that feature. See
You can get NMEA-2000 in the low-cost RAY50 model, and it sells for a very modest $250.
posted 01-28-2015 10:52 AM ET (US)
If your boat does not already have a NMEA-2000 network installed and powered, you will have to also consider the cost of adding the network. I'd use $100 as a reasonable figure for the cost of the network with self-installation by the boat owner. Of course, you might already have a network installed. If so, the cost of adding one new device is rather low, perhaps not more than the cost of a Network-T connector or a drop cable.
posted 01-29-2015 11:59 AM ET (US)
If you want the least expensive VHF Marine Band fixed-mount radio with NMEA-2000, choose the SIMRAD RS-12. It is only $200.
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