Getting lost trying to figure out GPS

[OK Toon]

I'm hoping you all can help me. I have a Humminbird Matrix 15 Fish Finder which is GPS Ready. I know I can add the Humminbird AS-GR16 GPS Antenna. But I think this will just give me information on my LAT/LON of where I am. I want to see where I am in relation to the channel in the lake. I saw where I can attach an external GPS, but I have a Garmin 205w that doesn't appear is compatible with the Humminbird Matrix 15.

So what do I need in order to see the location of the channel and where I am in relation to the channel -- using the Humminbird Matrix 15 unit?

Thank you for your help.
Steve

[MH Hawker]

Contact Humminbird and ask its their unit.

[Texoma Toon]

From the Matrix 15 Manual
GPS Connection Cable: adds GPS capability to the Matrix unit by connecting a handheld or other NMEA* GPS-compatible device. GPS capability instantly turns your Matrix into a Combo-Trackplotter to show position, breadcrumb trail and waypoints on the big, easy-to-read screen, all with big, easy-to-use buttons that handhelds do not offer. In addition, you can store up to 750 waypoints and 10 tracks inside the Matrix unit!

Looks like you need the correct GPS optional cable to connect to a NMEA compatible External GPS device. No antenna should be required. The external GPS should have the lake maps built in or you should be able to download them.

[oldmn19]

Don't know about Humming Bird, I have a Lowrance unit that has GPS and water depth, fish finder. I find I use the water depth reading far more than the GPS. The GPS would be important on a new lake, but again water depth is far more important to me! Remember the bottom changes from storms and water level fluctuations that the GPS won't show. Just my 2 cents.

[OK Toon]

The Humminbird shows the depth. The problem is when I'm running in 26' deep in the channel and then I drop to 2' when I wander out of the channel. Then I start roaming back real slowly trying to find the channel again. The GPS and plotter would just allow me to see which way I should be looking for the channel and where I am in relation to the channel.

[Texoma Toon]

Ok Toon, I am not sure a low end GPS is really going to help you that much. They can be off by 7 to 20 ft or more depending on the signal strength and how many satellites they are triangulating.
That being said I am surprised there are not any channel markers or buoys to show the safe boating lane. If this is a heavily traveled channel then I would think whoever patrols Eufalla would get tied of pulling boats that draw more than 2 ft off the edges of the channel.
I don't know how long the channel is but you may be better off taking some time to cruise slowly down the channel and when you have to make a turn look for a permanent landmark on shore and memorize the route. In 26ft of water I would think you could spot where the bottom starts coming up quickly and make your turn back to the main channel.