I use Beach 1 on dry and damp sand and Beach 2 on wet and surf. Why? I found the factory design works.
From the user manual: note the reduced transmit power of Beach 2
In the end, you’ll have to adjust to what best suits your specific conditions.
Just the view from my foxhole...
Beach 1 — Wet / Dry Sand
Beach 1 is most useful for detecting in wet/
dry beach sand and also in shallow water where conductive salt signals are prevalent. It has good sensitivity to coins and small/large jewellery. Beach 1 reduces the salt signal, while maintaining high transmit power, and still being sensitive to desirable targets. Beach 1 Multi-IQ processes a low frequency weighted multi-frequency signal, and uses special algorithms to maximise ground balancing for salt.
Beach 2 — Underwater / Surf
Beach 2 gives the best results when either wading
or shallow diving, with the coil and/or detector fully submerged. In these instances, there is a very strong salt signal present, so Beach 2 has a lower transmit power, which results in much less noise. This profile may also be useful in dry conditions where there are extremely high ground noise levels. Beach 2 Multi- IQ processes a very low weighted multi-frequency combination, using the same algorithms as Beach 1 to maximise ground balancing for salt.