The sounder is for the Avon dinghy. It's an older dinghy, very basic wiring. There is electric start and engine shifting controls at the bow helm. I have not looked at the wiring coming to the tach, yet, I guess that's from the the engine control panel, because I did not notice any wiring off the battery other than the main wires to the engine. I can run a separate wire to the battery, just much, much simpler to tap right off the tach, use a fuse there. The tach is right beside the depth sounder I mounted, much simpler than running an entire new line. Don't want to destroy the accuracy of the tach, though. Really appreciate all the suggestions and assistance.