I find this thread fascinating in a train wreck kind of way.
If I had lent this guy my bag and fin to use, and he lost them, I'd expect him to replace them.
But having something fall out of a boat just lies in a different category for me. If the guy who owns the boat had insisted that you put things somewhere you didn't think was safe, and had been a jerk about it, I'd want him to replace stuff when his strategy turned out to be bad. But if I put something down someplace without realizing it's at risk, and it falls, that's just bad luck. If the boat owner had OFFERED to replace the missing stuff, that would have been a gracious gesture of responsibility on his part. But if I'd been in your shoes, I wouldn't have asked or expected it. And if I owned the boat, and had taken you out on it as a nice gesture and a good way to get in a dive, and you got all upset about losing a bag and a fin off my boat, I probably would have agreed to pay for the replacement, but I wouldn't invite you back on my boat again.
If I had lent this guy my bag and fin to use, and he lost them, I'd expect him to replace them.
But having something fall out of a boat just lies in a different category for me. If the guy who owns the boat had insisted that you put things somewhere you didn't think was safe, and had been a jerk about it, I'd want him to replace stuff when his strategy turned out to be bad. But if I put something down someplace without realizing it's at risk, and it falls, that's just bad luck. If the boat owner had OFFERED to replace the missing stuff, that would have been a gracious gesture of responsibility on his part. But if I'd been in your shoes, I wouldn't have asked or expected it. And if I owned the boat, and had taken you out on it as a nice gesture and a good way to get in a dive, and you got all upset about losing a bag and a fin off my boat, I probably would have agreed to pay for the replacement, but I wouldn't invite you back on my boat again.