did you know that if you have Navionics Platinum you can take advantage of the 3D view? Check this out
3D View allows you to customize your chart to highlight key features for a better awareness of your surroundings.
Some of the key features are:
Pan & Zoom
Enjoy a broad overview, easily pan around the map and zoom in to any area you are interested in.
Exaggerate chart features
Increase exaggeration to Intensify and highlight subtle changes in bottom contours while following a channel or looking for good spots to fish!
Adjust pitch and rotate
Adjust pitch to change your vantage point from direct top down overview to a nearly horizontal view. Rotate the chart to any orientation to get a more direct heading view.