I used mine for the first time last weekend, also had to use a negative 15' to get the depths right. Yes it would of been nice to know this. I know with the lake this low, I have seen trees that I haven't seen in years. Also idled through a spot in wrights that I usually run through, smacked a pretty good size one. I really like the idea of being able to highlight shallow water and the highlight a certain depth, will be useful when trolling. I hope they map Ozarks and Twain one of these days, good bye Navionics!!!!
Ted
Neither snow nor rain nor heat nor gloom of night will keep me from crappie fishing!
2010 Lake of the Ozarks Super Slab Champion