Why Does the Depth Shading Extend Further Than I Have it Set?

The Navionics® Nautical Chart database is built with "depth areas". These depth areas are going to be a range of depths based on how the chart database is set up. For example, if there is a depth area of <17ft and a depth layer of 17ft - 33ft, this means that when you set your depth shading to 20, it shades the 17ft - 33ft layer. The reason for this is because 20ft is within that range.

Within the SonarChart™ layer, depth areas are set to 1 foot intervals. SonarChart is available within the Navionics Boating app during the initial trial period and during an active subscription, as well as with a Navionics GPS plotter card.