Yeah, I'm definitely not diving with him ever again.
If I had stowed my own gear, I would definitely take full responsibility for its loss, as I have done several times before. But since he was basically the skipper of the boat, and asked for my gear, and was the one who placed it there, that I was entitled to ask for replacement.
I'd like to stress also that I did not ask for money to cover this. I didn't want money. All I wanted was a replacement- if he got it from Ebay, Craigslist, used, new, whatever, I wouldn't have cared, as long as it was a working fin just like the one I lost.
It's weird... he's a new diver (but an experienced boater), right out of the gate (I think this was his 2nd post-class dive) and he'd found me and wanted to dive and learn with somebody who was experienced. I didn't really know him, nor was he a friend, before our dive yesterday.
Soo..... divers, beware!