I'm still looking for the condos i sank over 20 days ago it still does not show up on my graph, Now, i'm gonna go and take some 10' joints of pvc, screw them together and try to locate them the old gps i have gets me within maybe 18-20 feet on a good day, but thats 18-20 feet in any direction, so i'm guessing it should be within a 40' circle. thats a lot of error to be off if you can't see the darn thang to start with. its sitting in 30' of water, about 9' tall and 8' wide, with a length of about 18'. I didn't think of putting anything in there for a positive sonar reflection, but when i do find it, if i do :D there will be something added for sure, like a willow tree about 20' tall. boy this is a lot of fun, scubas next.