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ContinuousWave: Small Boat Electrical
GPS, Fishfinder, and VHF
|Author||Topic: GPS, Fishfinder, and VHF|
posted 03-20-2006 12:02 PM ET (US)
I have a Garmin 76 GPS and Hummingbird Matrix 17 depth finder. Based on
what I read in the West Marine catalog, they can be linked with the
purchase of a GPS connection cable. I need to purchase a VHF marine
radio. Based other material that I read in the West Marine catalog you
can link a GPS to a VHF, which can send out a DSC distress signal with
the boats coordinate position.
My question is; can all 3 be connected by one cable to each other?
Cabela's Marine catalog has a GPS Connection Cable, which is referred
to as a Y cable. Would that be a 3-way cable that would link all three?
In reviewing my Matrix 17 Operations Manual, I was only able to locate limited information regarding attaching the GPS to the Matrix. I called the
Can anyone out in the Whaler World enlighten me?
posted 03-20-2006 02:20 PM ET (US)
You can run one NMEA output to multiple (up to about four)
NMEA inputs, but each input can only be connected to to one
The fishfinder has only NMEA out.
So who can do what with the other guy'd data?
The GPS can record depth with waypoints and maybe in the track
The radio can take position data from the GPS. The radio may
But I don't think your GPS 76 can display it. So here's what
Fishfinder NMEA out (can't find the color code) to GPS NMEA in
GPS NMEA out (brown) to radio NMEA in (don't know color because
All three grounds together. Keep the ground and signal
posted 03-20-2006 02:22 PM ET (US)
As an explanation of my first paragraph:
If you have three people standaround talking, if one talks,
posted 03-20-2006 05:56 PM ET (US)
What sort of NMEA-0183 protocol data does the SONAR provide to the Chartplotter/GPS?
What sort of NMEA-0183 protocol data does the Chartplotter/GPS provide to the SONAR?
posted 03-20-2006 07:28 PM ET (US)
The fishfinder provides what it knows to the GPS: depth, speed,
water temp etc. What the GPS can exploit is another question.
The GPS can't provide anything to the fishfinder because the
posted 03-20-2006 10:16 PM ET (US)
As best as I can make out, the problem at hand is this:
The SONAR, a Humminbird Matrix 17, can accept input from a GPS in order to allow the SONAR to display some of the data on its large screen. This is a very simple connection:
GPS NMEA-output to SONAR MNEA-input.
Also, it is desired to interconnect the GPS to the VHF RADIO. The radio can accept inputs from a NMEA source. This is also a simple connection:
GPS NMEA-output to RADIO NMEA-input.
Solution: Investigate the GPS to see if it has multiple outputs. If yes, configure the outputs to send the proper NEMA data sentences to the device connected to each output. If the GPS has only a single output, connect it to both the SONAR input and the RADIO input. Configure all the necessary sentences to be sent on the single output.
The owner's manuals of all the devices will provide the details about what pins on what connector to use. The GPS will have to be configured to transmit the proper data sentences.
posted 03-21-2006 12:51 AM ET (US)
Jim: FOR THE THIRD TIME: The sonar has no NMEA IN. It can't
accept data from ANYTHING. It does have NMEA OUT that can
be used to send depth, speed over water, water temp, etc.
to some interested instrument.
But if it did, you wouldn't need multiple outputs. You can
posted 03-21-2006 04:52 PM ET (US)
Chuck & Jim
The following is from the West Marine web page Product Advise / West Advisor:
The latest on Digital Calling Service (DSC)
Before you can use DSC you must obtain a Maritime Mobile Service Identity (MMSI) number. When you apply for your MMSI you will submit information about you and your boat, which is then stored in the US Coast Guard's national distress database to be used in the event of a rescue situation. Until recently the only way to get a MMSI number was to apply for a ship radio station license from the FCC at a cost of about $90. Recently, the FCC has entered into agreements with MariTEL and BoatUS to issue MMSIs to "exempt " recreational vessels. Exempt vessels are classified as under 20 meters (65 ft.), not carrying a single side band radio or satellite communications equipment, and not using a VHF radiotelephone in foreign waters. To get free MMSI registration call MariTEL at 888-627-4835 (888-MARITEL).
posted 03-21-2006 07:00 PM ET (US)
Junie, there's no surprises there for either jimh or myself.
Boat US is one of several organizations handing out MMSIs.
That said: The Humminbird Matrix 17 Manual only speaks of
It also says it outputs the GGA NMEA sentence, which comes
posted 03-22-2006 08:52 AM ET (US)
I have connected to NNEA receiving devices to a GPS with no problem. I used a 4 position terminal block and crimped ring connectors on to the wires within the cable, and then attached those to the terminal block. The data-out on the Gps goes to the Data-In on the two other devices. Data-In on the GPS goes to Data-Out on the two other devices. Grounds tie together. The electronics used to drive the signal levels will typically handle two devices without a problem. When you start getting more than that, you need some kind of splitter, hub, or repeater.
posted 03-22-2006 08:53 AM ET (US)
Phat Phingers this morning. The first sentence above should read "I have connected TWO NMEA devices together without problem".
posted 04-07-2006 06:24 AM ET (US)
i have icom FP 561 sounder cum GPS. i want to connect this unit to PC and wants to transfer lat/long position with deapth of that particular point to Computer is it can be possible
posted 09-15-2007 09:44 AM ET (US)
Can the Garmin eTrex Legend GPS be connected to VHF radios with DSC capability?
posted 09-15-2007 11:33 AM ET (US)
All VHF Marine Band radios use NMEA-0183 serial data inputs (except for the newly announced Lowrance radio which is the first to use NMEA-2000 connections), so any GPS device which can output NMEA-0183 data can be connected to any VHF Marine Band radio which accepts NMEA-0183 data.
To discover if a particular GPS device provides NMEA-0183 serial data input or output I recommend you consult the manufacturer's literature. For GARMIN devices I believe they have a rather elaborate website which provides data about their products, and this ought to be able to give you information on a particular device's NEMA-0183 capabilities.
posted 09-16-2007 11:10 AM ET (US)
It is also important to check capabilities of the NMEA-0183 "sentence" structures for each device. Connecting them does not insure that the data is usable.
To use expand upon Chuck's talking analogy, if one device is speaking in French but the other can only understand English then there will be no usable communication even though they can hear each other.
posted 09-17-2007 01:18 PM ET (US)
bsmotril, If I interpret your posts correctly, you have connected two devices to your gps, so you have a total of three devices linked together?
I currently have a Garmin gps (76 hand held) linked to a Garmin fish finder. The two talk nicely to each other. I can configure the fish finder to display data from the gps such as speed, time, bearing, ETA, etc, and I can also send way points, depth, and temperature to the gps. If I am understanding correctly, I could also simultaneously connect a DSC radio to the gps?
By the way, for Garmin GPS users, you can get connector plugs from http://www.pfranc.com/ . I bought (made a pledge) a couple male plugs from this guy and made my own interface cables.
posted 09-17-2007 03:19 PM ET (US)
Newt, you can have the GPS send position to the radio,
(two listeners (radio and fishfinder) on one talker (GPS)
posted 09-17-2007 04:28 PM ET (US)
Thanks Chuck. I guess there is no reason for the radio and fish finder to talk to each other...or is there?
posted 09-19-2007 08:14 PM ET (US)
The http://www.pfranc.com/ guys have been offering Do-It-Yourself Garmin plugs for pledges since I bought my Garmin 45XL (back when they were brand new '94-'96). They're an excelent resource for the Garmin plugs.
Purchase our Licensed Version- which adds many more features!
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