Metal detectors make for a good stage prop for a guy to have a reason to be out wandering around unattended! Heck, dont even have to have batteries in it for it to be an effective 'I'm harmless' visual!
A lone old man should not be seen in a totlot or a park or wandering around on a curbstrip with no obvious reason to be there! So yeah, same with the beach! That would just be creepy!...
For one,, If the girls did not want to be seen,, Than they would not dress like that..
I sure don't mind looking at them when I am in the water trying to detect.
It takes my mind off things..