Moderated Discussion Areas
ContinuousWave: Small Boat Electrical
Separate GPSr and SONAR In Lieu of Combo Unit; UNIDEN Oceanus VHF
|Author||Topic: Separate GPSr and SONAR In Lieu of Combo Unit; UNIDEN Oceanus VHF|
posted 04-14-2008 10:22 PM ET (US)
I have been looking at combo units (GPSr, chartplotter, and SONAR). I am an admitted newbie. This will go on a Whaler Montauk. Shopping around I noticed the Garmin 172c and 250c FF would be about the same price and give me a larger viewing area. I guess with charts there would be some additional safety should one die? So why not go with two units? The dash space will be tight but this is for catching fish not looking pretty.
will the 172c connect to an Oceanus VHF?
posted 04-15-2008 09:04 PM ET (US)
The advantage of two units is more pixels, faster display
(processor only needs to do one thing, not two), and some
degree of redundancy (I can get home by following the 100'
contour if it's really foggy and the GPS dies.).
Down side is when you run over some fish with the depth finder
Garmin 172c will probably connect to an Oceanus VHF, HOWEVER,
posted 04-15-2008 09:47 PM ET (US)
Here you go .... page 5 & 54 of the Oceanus owner's manual. The Oceanus can only receive NMEA data from from the Garmin 172.
posted 04-15-2008 09:51 PM ET (US)
There are two models of the Oceanus one is DSC capable and the other is not.
1. Oceanus DSC (DSC capable)
2. Oceanus (not DSC capable)
posted 04-16-2008 12:17 AM ET (US)
I raised this same topic in a prior discussion. See
Display Size of Combination Electronic Chart Display and SONAR
I have come to believe that we are now at a point in the market price of these devices where a large premium is paid to get a large display, and the cost of two smaller displays which provide as much (or more) screen space may actually be less than one large display.
The points made regarding faster operation due to dedicated electronics and regarding greater redundancy are also cogent.
posted 04-16-2008 12:39 AM ET (US)
I have the DSC capable model of the Oceanus. Now I am a complete Newbie to boating. Why can one not hit the way point when you see the fish? Is the [SONAR] cone so wide that you might mark a spot a significant distance from the fish?
How are these two units?
posted 04-16-2008 09:10 AM ET (US)
The width of the SONAR transducer sensitivity is measured in degrees to some (unspecified) reduction in signal level, probably about -6dB, so the distance offset from the boat's position of a target producing an echo depends on the depth of water. If the transducer is a 20-degree device, and you are in 500 feet of water then the target producing an echo might be
500 x SIN(20) = 170 feet
offset from the keel centerline.
posted 04-16-2008 09:15 AM ET (US)
Regarding interconnecting a VHF Marine Band radio and a GPS receiver, this is done almost universally by using a serial data connection which conforms to the NMEA-0183 specifications. Check to see if the devices you want to interconnect both have NMEA-0183 serial ports. Typically the VHF Marine Band radio will want to receive the NMEA datagram for current vessel position such as GGA, GGL, RMC, or similar. Most GPS receivers can produce that datagram.
posted 04-16-2008 09:24 AM ET (US)
Regarding the Digital Selective Calling (DSC) features of a VHF Marine Band radio, there are several levels or classes of these features. For a while radios which were sold in the United States conformed only to a limited sub-set of the available DSC features, and these radios were denoted as being RTCM SC-101 compliant. This category of radios is still being produced at the low end of the market, but the United States Coast Guard recommends that you use a radio with better compliance, one that meets the DSC Class-D rating.
For more information about Digital Selective Calling and the specifications for it, please see
Digital Selective Calling: Class–D
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.