Sand has to be the most unstable of environments for coins which means they sink deep. Here is an excellent article by Dankowski regarding his experiences in Florida which is sand city.
http://www.dankowskidetectors.com/loveisdeep.htm
The coin depths he was seeing in a sand environment(I assume because it was in Florida) at one location was
60's coins 8.5"
50's coins 10"
20's coins 11"
1890's coins 12"
It is a good article and I quote him on his last paragraph
"How do you know what you are missing, if you do not know that it even exists! As a coin sinks in the earth, the deeper it goes the slower it will sink because the dirt is more compacted at depth. Once again, the coin will stop sinking when it reaches the level in the soil that is compacted enough to equal the density of the coin; and that’s deep! How many areas do you think you have passed over and missed good targets? I think that you would be startled if I were to tell you that the answer would be just about every time you turn on your detector. When your favorite manufacturer releases a new detector that goes a little deeper, you will have major things to look forward to. "
George
http://www.dankowskidetectors.com/loveisdeep.htm
The coin depths he was seeing in a sand environment(I assume because it was in Florida) at one location was
60's coins 8.5"
50's coins 10"
20's coins 11"
1890's coins 12"
It is a good article and I quote him on his last paragraph
"How do you know what you are missing, if you do not know that it even exists! As a coin sinks in the earth, the deeper it goes the slower it will sink because the dirt is more compacted at depth. Once again, the coin will stop sinking when it reaches the level in the soil that is compacted enough to equal the density of the coin; and that’s deep! How many areas do you think you have passed over and missed good targets? I think that you would be startled if I were to tell you that the answer would be just about every time you turn on your detector. When your favorite manufacturer releases a new detector that goes a little deeper, you will have major things to look forward to. "
George