Officer_B, you should be able to flip switches and see if they do not appear to activate anything. If you find one that was an acc switch and not utilized, you can look at the back of it under the helm and note the colors of the wires. From there follow the wires and if there's a harness at the end of them that's a dead-end, you can tap into that to power the depth finder. The other option would be to tap into the main coming from a main switch (if you have a master) and put an in-line fuse to the depth finder and it will come on whenever the master is flipped on.