depth finder shuts off when nav. lights are turned on

[Never Enough Time to Fish]

I have a 2000 Lund 1650V Rebel with a Humminbird 100sx depth finder. The depth finder power wires are connected to the back of the fuse/switch panel at the nav/anchor lights fuse. The fuse for the lights is 5apms. The manual for the depth finder says to use a 1 amp inline fuse. I looked, but did not find one. Is there a way to keep the depth finder power wires connected to the fuse panel or do I need to run those wires directly to the battery and install a 1amp inline fuse? Thank you for any advice you may have.

Never.........

[JIM PAYNE]

I am not sure how it all works but if you have a 5amp circuit and you want to put a 1amp system on it you can just put a 1amp fuse on the wire between the 5amp and the unit you are hooking up.

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JIM PAYNE

[Surface Tension]

Get the 1 amp fuse.
As for your depth finder turning off theres a few possibilities. Most likely you have a bad connection somewhere between the battery and the fuse panel. Improper gauge wire to your fuse panel or dirty contacts on your nav lights. Your depth finder has a range of voltages it can run on and when you turn the lights on the voltage fir an instant drops below that range and the d/f shuts off. I'm willing to bet you can start the d/f backup with the nav lights on.
Clean the battery connections, if that doesn't solve the problem wire the d/f directly to the battery and as Jim suggested with an inline 1 amp fuse.

[Enids Hubby]

I also have a humminbird 100sx on my boat. I have all my electronics hooked up to the one deep cycle battery , the 25hp elect start motor, the depth finder, the elect trolling motor, nav lights and bilge pump , I do have a one amp fuse inline for the depth finder . my depth finder will go blank when the battery is very low and I turn the elect trolling motor to the high speed . never have a problem with a charged battery . I have a bunch of skinny wires hooked to fat wires some soldered some crimped . I would check for large current draw in nav light cuircut.