Hi Seahound!
Your profile says that you are a film/doc. producer. I do a little bit of that myself. I'm sure that you have access to legal advice as to copyright issues, and knowledge from prior works you've done. My wife is my assistant, and she spends several hours per week tracking and paying out royalties, or acquiring rights to various works.
As I'm sure you know, information and ideas cannot be copy written. You cannot copyright knowledge of wreck locations. You can write a book about it, and copyright the book, but not the information in it. But ALWAYS seek legal advise from a professional.
OTOH, this guys financial integrity may be in question, but the integrity of your word may be viewed as well.
Never enter into any form of agreement without putting it in writing.
Just my 1 cent.