I recently purchased a new boat that included a Raymarine C70 Chartplotter and Pathfinder radar. I am having some problems interpreting the images on the radar screen. Does anyone know of a book or video that would help me figure out what is going on and how to use this piece of equipment properly? I have read the manual, but that doesn't say too much other than how to work the controls. At this point, I am getting frustrated and would appreciate any advice from the readers.Thanks