Fishfinder Interference

[croaker stroker]

I have been trying to solve the problem of "fish" appearing on my fishfinder when I accelerate.  I read a post from Fishing Eagle about transducer position, so I carefully changed the position of my transducer like he suggested. I am still having the problem.  I have had similar problems on other boats caused by electrical interference from the ignition system.  Those boats had V8 engines and I was able to purchase resistor spark plugs and a resistor for the coil wire, which eliminated my problem back then. I have found no such products available for my little 50hp Yammi.

I now have a Humminbird 717 finder, which works pretty good.  I have a Humminbird 788ci that will arrive on Thursday, so I want to figure out this problem before the new finder arrives.

I spent a good part of the day yesterday re-routing my Transducer cable to the port side of the boat, away from any electrical cables.  I had to drive a ways to locate a 10' extension cable because I had to rout the cable all the way around the bow. (open bow boat)
I'll post up after fishing on Tuesday.  If this doesnt work, I think I'll try the transducer inside the hull.

Any other suggestions??

Does increasing the upper limit on the sounder do anything to avoid reading bubbles from the hull??

[StreamFixer]

Perhaps there is a species of fish in your warm waters that moves so swiftly you can only pick it up on your fish finder when you are accelerating and moving swiftly?     And that my friend, is the absolute limit of my knowledge in this area.

However, I am pretty sure you needed at least that basic observation.  Maybe that will help eliminate one possibility   :whistle:

StreamFixer

[croaker stroker]

All that time studying Fluvial Geomorphology has apparently finally paid off. Thank you for your valued observation.  

                                                             

[fishing eagle]

Croaker you may not have the same interference or fish symbols on your new Humminbird. Different units can very well perform differently. Have you gone to the Humminbird website and registered your 717 unit and then checked for software updates. Humminbird has a decent support for registered owners and it will list any available updates and firmware for you fishfinder. The problem you described was fixed on a previous humminbird unit I owned with new firmware. Not all units can be upgraded as it depends on what they are. Usually all GPS units can be upgraded because you use a memory card to upload the software to your Humminbird after downloading it to the card with you computer.The 788ci can positively be updated! You may even find that there is one or two firmware upgrades available at Humminbird as this is normal.

[croaker stroker]

That might be the problem.  To download the upgrade for the 717, I needed to buy a cord to connect to the computer. (no card slot)  I didn't want to buy one since I was going to buy a new fishfinder anyway.