To make the most accurate and user-friendly Insight Genesis maps, make sure your GPS receiver is aligned properly with your transducer. If your transducer is transom-mounted and your Lowrance unit is console-mounted or bow-mounted, your mapping results won’t be as accurate as they could be. To make the best custom contour maps possible, install a thru-hull transducer below your console, or install a stand-alone GPS antenna “puck” in the stern of your boat, above your transom-mounted transducer.
Your boat’s GPS receiver is built into your Lowrance unit. Mounting your unit at the console and connecting to a transom-mount transducer creates a gap of five feet or more between your GPS position and the portion of the water column that your transducer is sounding (and displaying a representation of on your screen). This can be especially problematic when mapping an area with up-and-back/shore-to-shore horizontal passes, as such a set-up can cause the location of mapped depths to be five feet off (or more) in one direction and another five feet off (or more) in the other direction.
A tell-tale sign that your transducer is located too far from your boat’s GPS source is “crinkly” looking contour lines on your map (see yellow circle in Figure 3).