I have a GARMIN 178 Chartplotter and Sounder. There is a faired fitting under the hull which incorporates the sounder and through the front half of which is the hole for the paddle wheel for the speed log.

When I launched Exodus (235/51) I put the blanking plate in to prevent damaging the paddle wheel. I then sailed off and hey presto, the speed log works as usual!

This makes sense as satellites will detect the unit moving just as they do in a car - after all, we don't trail a little wheel behind us to make the satnav work in the car.

So why have I got a hole through the bottom of the boat if the speed log wheel is redundant? Answers welcome please!

Stephen Godber

235/51 "Exodus"

A paddle wheel will give you a speed through the water....

Maybe there is a setting to give you speed options if the wheel is fitted ????

Hope that helps.....!

Paul Burton.

Parker 21 Papillon.

I would agree with Paul, GPS gives speed over ground, the log gives speed through water.

If the GPS goes down for any reason you have a backup system to calculate your position.

Also, the difference between each should give you the amount of tide running. All useful information.

Regards

Graham Ebb

235/25 Blue Jazz

Thanks Guys - assumed there was something like that as an answer, same as in flying there is groundspeed and airspeed (which itself divides into true airspeed and indicated airspeed!).

Wouldn't want to not use the log wheel what with all the fun of the water fountain effect enjoyed whilst installing it!!

Stephen Godber

235/51 "Exodus"

I have a Garmin 178 along with a Cobra DSC/VHF,however i cannot get the GPS an the DSC to talk to each other

I have followed the wiring in the manual to connect the nmea on the DSC to the GPS, the DSC is red and black, and if memory serves the GPS wires are white and green

Am i doing something wrong ??

Any suggestions

Cheers

Peter Lowry "Cleo" (seal 26)

I have a hand held Garmin GPS that I wired in to my DSC VHF. The problem I had was that the Garmin products are set as default to output in the Garmin format. This needs changing in the settings to output in NMEA format.

Not sure if this is your problem, but it is worth checking.

Regards

Graham Ebb

235/25 Blue Jazz

Peter - I have exactly the same kit (178 and Cobra), and I had the same problem, despite it all being new from Parkers!

(See my post re.VHF / DSC April 2007)

I spent a very long afternoon last year trying every single combination and eventually succeeded - I think a blue wire is involved....

When I next go down to the boat I'll tell you the right wiring - it maybe today but otherwise it will be next week.

Stephen Godber

235/51 "Exodus"

Peter - rowed out to Exodus today and can confirm the following:

Mine was originally wired Black Cobra to Black Garmin and Red Cobra to Green Garmin - this is WRONG!

Correct is BLACK COBRA TO BLACK GARMIN - this maintains the earth.

The RED COBRA CONNECTS TO THE BLUE GARMIN.

You may also have to click on the tabs on the left of the Garmin screen (press Menu twice to get these up) and select the "COMMS" tab. This gives a sub-menu of "Garmin" or "NMEA" - select "NMEA".

Trust this helps, good luck!

Stephen Godber

235/51 "Exodus"

Will be on board at the weekend and will let you know if sucessful

cheers

Peter lowry

I can confirm the GPSMAP178 has 2 ports, http://www8.garmin.com/manuals/...Sounder_OwnersManual.pdf 

Port 1 NMEA out is the blue wire and this should be connected to the NMEA IN on the VHF.

The NMEA -ve is common and should be connected to the VHF NMEA -ve.

As mentioned earlier by others check and change the "communications" setting on the Garmin port 1 and set them to NMEA, 9600 baud.

Mike Edwards

Seal 28 "Aztec"

have been on Cleo today and have rewired the nmea SUCESS

many thanks to all

Peter