Theoretically, would a professional grade sea-floor sonar unit (the kind used to map the sea floor) be capable of visually detecting an object like a sunken structure or submerged boat? Thanks in advance for any responses!
Well, sonar gives the shape of the floor, so I would say it's possible to find a ship given it's not buried too deep. Depending on the shape, a structure is possible too, but it might blend in with the floor, making it look like a giant rock or something. About 20 years ago, some divers found an underwater pyramid off the coast of Japan. Given it's shape and the various life growing on it, it would be hard to detect with sonar. So, my advice is to make the structure not resemble something which could be found underwater.
Yes, easily. Current technology can produce pretty distinct images of the bottom, to include the outline of sunken wrecks. Sidescan sonar is especially effective and can be purchased in units that work on even the smallest boats. I had two such units on my last bassboat. Look at these images: http://stellwagen.noaa.gov/maritime/palmercrary.html http://www.wrecksite.eu/wreck.aspx?474 http://www.jpl.nasa.gov/history/innovations/1983_sunken_ship.htm http://oceanexplorer.noaa.gov/explorations/04gmss/media/robertelee_bridge_sonar.html
Those images are from commercial grade (common) units. The military has even more specialized and detailed units that allow submarines to navigate in tight underwater canyons.
