Took the GTI to the beach to run it through its paces. I hunted primarily in coins and jeweley mode since the area is filled with bottlecaps and foil among other things. Seems to be very good in the dry sand. Noticed that pennies come in at a lower tone than dimes and quarters. One issue I ran into was with interference. There are lots of hotels in very close proximity to the beach and I think the GTI was picking up radio waves from the antennas on their roofs. I've experienced this same issue with other machines in the same location. I tried changing the frequency but wasn't sure if I should go up or down on the numbers. Can any other users share their expertise in dealing with this?