Sounds like a PR problem that you are handling with a PR solution.
If your question is whether you are safe because the law stopped at the end of the dock, I doubt it.
I ride on jets all the time that have to go out over the ocean or great lake to power up. (Think Orange County... is that John Wayne airport?) I don't think that the noise regulation stops at the beach.
We have a sound law (never enforced) in our town about those dam Ricers and their boom boom systems. A cop can give you a citation if he can hear the noise from farther than 50 feet away.
I bet that if I am on the other side of the county line, with my stereo cranked up, and the cop hears it on his side of the line I have still broken the law.
Your sound may have started in the Marina, but it was when your sound HIT THE WALLS OF THE CONDO that you started waking people up.
My guess is that they have you... and that you are doing the right thing by making nice.