C-80 problem

El and Bill · Posted: Sun Feb 26, 2006 10:35 pm Post subject:

When you buy the new CR-21-EC mount a Garmin! -- sorry, couldn't resist!

Sea Skipper · Posted: Sun Feb 26, 2006 11:59 pm Post subject:

Ideally the C-80 should be connected to the GPS by SeaTalk which has a much higher bit rate rather than NMEA. The C-80 will convert the SeaTalk data to NMEA which can be connected to the Navman. Also for each NMEA port, it is best if you only have one NMEA talker & listener connected to each other. Both NMEA & Seatalk are digital signals so it is unlikely that a weak signal would result in a different speed reading. Perhaps one instrument is reading in MPH and the other in Knots? Or if you have the Raymarine depth~speed sender, you may be looking at speed over water (SOW) on the C-80 and speed over ground (SOG) on the Navman?

Hank Brooks
Sea Skipper

tpbrady · Posted: Mon Feb 27, 2006 12:32 am Post subject:

David,

I don't think its serial power issue since NMEA normally will "power" at least two devices. I have three powered by a single output on my Lowrance. I think it is an issue of how each device is interpreting the messages. The question is which device is recording the true speed. It's kind of like having two watches.

I would think a more classic installation would have the Navman taking speed over ground from the C-80 NMEA output and not from the GPS receiver itself if the C-80 has an output.

The GPS125 receiver is outputing in NMEA 2.3 format and the particular sentence the NAVMAN is looking is the GPRMC. There might be an issue with the NAVMAN looking for NMEA 2.2 or earlier output in which case the NAVMAN may not be decoding the RMC sentence correctly.

Only a guess, but it might be a factor.

flapbreaker · Posted: Mon Feb 27, 2006 1:45 am Post subject:

I vote for this...

Byrdman · Posted: Mon Feb 27, 2006 9:24 am Post subject:

I may be wrong here.... but it seems that in one of the menus on the C70 Raymarine, you could even calibrate the speed. I think it has to be in the sonar mode, then a couple/few button pushes.... I no longer have the system, or the books... But, when my brother Mike's grandson was "adjusting the screens" on one of their outings..... he did manage to re-set the speed calibration some how... Shocked

But at the same time... Mike had a brilliant idea.... no child goes forward without a roll of paper towels and windex. That worked great...and I could care less what the speed indicated.....I could SEE !!! CoolSmile

I recall post on a different thread about the speed being changed or calibrated in the sonar menu.

Yep, I had to grin with Bill on Halcyon....about the new purchases. Raymarine is real good stuff..... if.... you read a lot and push a lot of buttons. David, I have all the confidence in the world you will have this fixed too in no time at all. I use to keep my Garmin 76S sitting between my two Raymarine C70s on FreeByrd... because I was simply use to the flow of the button pushes.... and nothing like a bit of back up if all DC power goes away. There was a day when all three instuments agreed on the rate of speed....

gljjr · Posted: Tue Feb 28, 2006 12:50 am Post subject:

Is there a diagnostic screen on the C-80 that will let you view the raw NMEA data sentence? If so you could look to see what it is saying and compare that to what it shows.

Alyssa Jean · Posted: Tue Feb 28, 2006 9:24 am Post subject:

Gary, there is under Menu a window for the GPS and it shows the same speed as the Navman, however the window on the main screen shows the lesser number. That really confuses me.

I have the Icom VHF connect for Lat and Long but I think that is a separate wire for that signal. I think the speed signal is carried on different wires.

gljjr · Posted: Tue Feb 28, 2006 11:58 am Post subject:

David,

Since you are seeing two different numbers on the C-80 it seems you have a speed correction spot on the C-80 that is set wrong. It seems to me that you may want to find a lake with little to no current and tweak the speed to agree with SOG from the GPS. Then tweak the Navman to have the same readings. I'm sure it will differ from the raw data coming from the speed sensor but that would be OK.

My IRA · Posted: Tue Feb 28, 2006 10:53 pm Post subject:

David,

I think that there are two speed inputs, one from your triducer and one from the Raystar 125. You can calibrate the triducer reading to somewhat match the Raystar but they will seldom display an exact match due to the difference in the update speeds.

Jerry