A fishfinder, or depth finder, identifies fish and other objects below the surface of the water that are usually hidden from your eyes. Another feature of the fishfinder is something known as shading, which uses different colors or shades of colors to identify different objects. Changing the shading can help you see things more clearly.
Safety shading on fishfinders shows you the areas of the water that can lead to serious problems such as shallow water. Green colors on the map show dry areas, and blue shading indicates that you're traveling into deeper waters. The blue shades change as you travel into different water depths. If you see dark blue areas, you should be aware of possible dangers such as extremely deep water.
Selecting a Contour
When you use a fishfinder, you'll need to select a safety contour. This indicates the depth of water at which you're most comfortable, based on the size and weight of your boat. For example, if you have a heavy boat and typically spend time in waters 20 feet deep, you can set your safety contour at 20 feet. When you travel into deeper areas of the water, the fishfinder indicates this on the chart.
Changing the Contour
To change the shading on your fishfinder, choose the cartography setup button from the main menu and then select the safety contour option. Then use the directional pad to scroll through the safety contour options such as 20 feet, 50 feet or 100 feet. The map of the water then shows any areas where the water is deeper than this level and the safe areas for your boat.
Changing the Shading
Change the shading by selecting the cartography setup menu and picking the extra detailed feature. This feature lets you choose different colors and the shades of each color used for different items. For example, you may want to show fish in a bright red shape, which contrasts against the blue of the water. Try using shades that contrast against each other so you can easily identify the object on the screen.