If you want to search on the beach, then any cheap metal detector is suitable for you. Why any cheap metal detector? There are several reasons for this. You do not need to dig deep (no more than one bayonet shovel), respectively, a large depth is not needed. You do not need high sensitivity (because otherwise the metal detector will react to very small inclusions in the sand, but there will be no target in this place).
What Functions Should a Beach Metal Detector Have?
For a beach metal detector, the ability to discriminate aluminum caps and tongues from beer cans will be useful. There are such types of metal detectors. For example, Golden Mask 1+. It can be detached from the foil. The second option of a cheap metal detector for the beach is ACE-250 (but it will not work to rebuild ICQ from the foil).
To search for the second option, it is best to try underwater detector with a geometric case. For example, Garrett AT PRO. The short-term immersion in water for such a device is not scary. Usually, they are designed for immersion up to 3m. To search for a belt in water, it is best to take an underwater metal detector. As a rule, underwater metal detectors allow diving up to 10m, up to 30m, up to 50m, up to 60m. There are different options for beach metal detecting. As you yourself understand, any of these devices will suit you.
Search on the sea beach may be very difficult for a metal detector. Not every device can handle it. Sensitive devices (for example, Sorex PRO by AKA) will receive false signals about the target. But there will be no goal. This salty sand will give such a signal. But the ACE-250 is quite suitable for such a search. Underwater metal detectors are typically designed to work in salt water. For some devices, the instructions explicitly say that they cannot work on the sea beach. For example: Fisher F11, Fisher F22, Fisher F44.
What Other Instruments Are Needed for the Search?
When searching on the beach, a scuba will be extremely useful, which will sift sand through its holes and leave finds. Depending on the type of search, the handle on the scuba can be very short, medium or long. Often, they lean on scuba with their feet to dig in the target and not bend over.