Ronnie, what you are looking for are units that support the same "NMEA"
output / input. Some (most?) Lowrance units have this ability -- you
need a Lowrance NMEA/DGPS Adapter Cable (possible part number.....NDC-1
51-92) But check your dealer or manual to be sure.

NMEA is a standard that lets GPS to be connected to autopilots, VHF
radios, and other marine gear.

What I don't know is if the set up will let you go two ways -- ie:
input a waypoint on the master and the slave -- put it is possible.

Keep in mind, GPS (with WAAS enabled) is accurate to 7 meters (a boat
length) most of the time .... some studies site less than 3 meters (A
boat beam) 95% of the time.

In RGarri7470 wrote:
My new boat has a Lowrance depthfinder/gps on the console and a good
depthfinder on the front. Each has its own tranducer.

I had a thought last week - I know, a rarity for me - while fishing.
I was fishing a brush pile and had not put out a marker so I was
having a tough time staying on it. I wished my front depthfinder was
paired with the one on the console so it would show the waypoint icon
for the brush pile.

Would you buy a pair of depthfinders/gps that worked together? One
could be a slave to the other, or both could work off a central unit
under the console, maybe. Seems you would only need one tranducer and
one antenna for the pair.

I woulder how hard it would be to do this - how much more it would
cost. I can turn my console unit so I can see it while on the
trolling motor, but it would be nice to have both work together and to
be able to put in waypoints from either.

I think I will send this to Lowrance. What do you think?

Ronnie

http://fishing.about.com