Downrigger Question

[Fishassassin]

Out on my buddy's boat and his fishfinder shuts off or resets every time we dropped the downriggers in the water. He has a nice humminbird fishfinder and electric cannon downriggers. The downriggers have their own battery with nothing else connected. Any advice as to why they are causing the fishfinder to shut off?
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[Fly_Flicker]

Seperate batteries - but a common ground. Make sure all ground connections are tight and that there is no corrosion. I am guessing there is some kind of spike going on. Put a DVM on the fishfinder (power and ground)and watch what happens to the fishfinder voltage as the downrigger is enabled.
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[wiperhunter2]

Does it reset or just lock on the ball as it is going down?
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[Fishassassin]

it resets
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