I am about to install a fish finder/depth gauge on my boat that is going to used by myself and my three teen age sons. My question is, Where should I get the power source from?, one of the gauges, then the fish finder would be turned off automatically when the boat is turned off. Or on the anchor light. This would require someone to make sure they turn it off when they are through.<br />Or does it make any difference? <br /><br />Thanks in advance<br />Greg