If you want to use the Prizm 5 on the beach just ground balance it on the beach. If you want to use it in water up to your knees ground balance it in the water. This will help with the water detecting. I love my Beach Hunter 300. It is a fantastic fresh water machine!! I hunt in discriminate mode and dig all the Yellow and Green lights.
While standing in the water 6 inches deep turn the machine on and hold the coil down on the sandy bottom. The automatic ground balance feature will sense a slight difference and keep hunting in the water. Later upgrade when you can to the DFX or VX3 for the quickly adjusting Auto trac.