thanks Mike...that's the info I was looking for. I am probably going to move on the Premium Navionics chip as soon as I can scrape the coin together.
I was a little mislead by the marking on the "US Basemap" version of the HDS that I have. The demo unit running basemap at BPS showed contour lines and the salesman said "that is standard for US Basemap and winni would be covered" and the documentation that comes with the unit shows every shot of a chart having contour lines BUT all I have is "blue" for water and "yellow" for land and my track line. I might be missing a setting but Lowrance and BPS certainly do everything to lead you to believe you get a quality chart with US Basemap with bottom contour (Bathymetry).
Mike,
I run the Navionics platinum chip on my Humminbird 997 and love it. I don't use the 3D feature a lot but those 1 foot contours are spot on and help me stay out of trouble on my trolling passes. I was amazed at how accurate the contours are on Winni, Sebago, etc... I think you'll be very pleased with the platinum chip if that's the route you go.
