Custom Shaded Danger Zones
A pioneer in user-optimization was Raymarine, which several years ago began presenting software in its e-series chart plotters, allowing users to change depth shading on Navionics' platinum charts. While 60 feet is the National Oceanic and Atmospheric Administration danger line (that depth and shallower is shaded a darker blue on government charts), most recreational boaters worry only about water less than 20 feet deep. Recently, Furuno partnered with C-Map, and Garmin tweaked its BlueChart g2, to allow adjustable danger zones too — and let you shade them in bright orange or red, if you choose. Lowrance and Simrad offer similar optimization.