[dgax65]

It may cost and weigh a little more, but using two seperate batteries / circuits can eliminate some problems. Having the bait pump on a seperate battery pretty much eliminates any chance of electrical interference affecting your fish finder or GPS. The pump will generally draw more current than all other loads combined. With a seperate battery for the pump you don't have to worry about killing all of your loads by running the pump too long. This could be important for those who use a combination fish finder/GPS for navigation.