I am not authoritative on the matter but I tried running a second FF (it was the original that came with my first boat) along with my upgraded sonar years ago. I had the transducer of my dash mounted sonar on the transom and made the older sonar "portable" by setting it up on a removable plank on the stern and attached its transducer to a small piece of wood clamped onto the opposite side of the transom. When I ran both...both displays became unreadable. I asked questions about this on a few different boards and was told that doing what I did causes interference on both transducers and that the transducers need to be more seperated (like guys who put on td on a bow mounted FF and one on the stern that goes to the dask FF). Not sure I believe this to be true. I think another option MAY be to use FF from same manufacturer and PERHAPS share the transducer if that is possible.
I have to admit, I would LOVE to have a fish finder back by my downriggers. Especially when going deep for lakers when we try to keep the DR balls only a few feet from bottom. We usually put a guy on the DRs to bring each up quickly if bottom comes up....that guy is always asking "how are we doing on depth" and relies on the guy in the drivers seat to be constantly watching depth and being proactive in reporting when its time to bring DRs up a few feet. At least one of the guys on my crew is not good about driving and reporting bottom problems. It would be nice to have a second set of eyes on depth at times like these.
i run 2 different xducers for 2 different units, one port, one starboard. no interference issues.
Thanks for the replies. I thought the same thing about linking the two together but the helix 7 is not compatible with the 787, guess it's too old. I know a lot of bass fisherman use a second sonar up by the bow but have read mixed reviews on putting both pucks on the transom. Some seem to think if it runs on a different frequency it will work. I guess I'll try it out before drilling any holes and permanently attaching the transducer incase I need to move it to the bow. I think I'll shoot hummingbird an email and see what they recommend. I wanted to put it on last year but once the boat was in the water I didn't take it out until the season closed.
I run a sidescan transducer and two others, the only thing I had to worry about was that the sidescan was lower than the others. One of the others goes into the Lowrance with the sidescan, and the 3rd is a redundant on a Raymarine. No issues with either, run them together all the time.
I emailed hummingbird and they gave me a vague/indecisive answer... basically that it may or may not work, being they are both hummingbird products they operate on a similar frequency. They suggested to try switching the frequencies around or to shut the sonar off of one when using the other. They said if that don't work to try moving the ducer' to the bow.