Back in the early 90's I was fishing in my first boat called the Sea Nymph "Fishing Machine". It was an early morning trip and the water was as flat as I'd ever seen it. Belews Lake is known for its clear water and that morning as I was trolling along the shoreline I looked down and seen what looked like a building that was still standing. About 10 - 12 feet down I could see the roof of a building. When I installed my Humminbird 997c SI NVB on my boat I decided to make this my first trip to see if the building was still standing. When I went over the building the first couple of times I didn't think it was still standing but I really couldn't tell for sure. When I updated my unit with the new bottom scan I made another trip to see how it would appear. The new bottom scan confirmed that the building was no longer standing.
P.S. Many thanks to Humminbird for allowing me to just go online and download updates for my 997c SI at no additional charge.