..........I have used my CZ 7A Pro in light rain where water accumulates in that recess for the panel with no damage to the detector.
I've used a dry paintbrush to dust away dry dirt on the panel as I fear wiping it down with a damp cloth could scratch the panel. Alternately, I've frequently LIGHTLY hosed it down to remove beach sand which is sharp and might scratch the panel or abrade the paint resulting in rust. I doubt that Fisher would recommend this procedure as they would be liable for damage should an improperly tightened or crimped seal violate the integrity of the weather-proofing. It would be routine engineering practice to test weather-proofed or submersible detectors at some degree of pressure but that would be proprietary information and not available to us. I conjecture that the CZ 7A/70 design was tested at least to one atmosphere or under 6' of water for a period of time.
That trivia out of the way, I'll once again relate my beach experience with the CZ 7A Pro.
As any avid beach detectorist can tell you, "The question is not IF, but WHEN you will get your detector wet!" Being that I was born and raised by the ocean where I certainly had my share of wet dunkings as a youth, you would think at my senior age I would be a lot wiser and drier. NOT SO!
I had been at the beach only about 20 minutes and observed the wave pattern, noting that the waves washed up no closer than 15-20' below a long cut in the sand about 5' high which I was to explore. I started detecting and turned around when I heard the roar of a huge rogue wave approaching with no means of quick escape. I was knocked down and dragged outward with the receding sand and water that also built up on the face of the detector. Once at home I lightly hosed it down to remove the sand and incurred no damage to the detector. Most other non-submersible detectors, including the CZ 5 and CZ 3, would be history.
The CZ 7A Pro and the CZ 70 may not be classified as submersible .......... but it's proven to be the next best thing.
Chet