Capt. Kym Ferrell told me moments ago over tasty(?) breakfast burritos that Roy Volker went down to Grand Cayman in the mid-60's and salvaged several wrecks off the Caymans until he was shown the door by the government. He also mentioned that Roy wrote about it in one of his first two books. I can only think of two: "
Treasure under your feet " published in 1974 and
In the wake of the Golden Galleons " (1976). Kym worked for/with Roy back in the 1980's and made that big find of 900 silver coins in 1988.
I haven't talked to her in a few months, but Karen McKee lives on Grand Cayman and her father, Art, salvaged down there as well. If you really, really want to know, she sometimes works as a paid researcher.
<Brief related Captain Kym story - On the way down to Cayman, Roy found a sandbar and ran aground on the west end of Cuba, but managed to refloat and get out of there before the Cuban gunboats found them. We think he was aboard the Virgilona, before he sold it to Mel.>
That's all I know and/or suspect. Good luck.