Sounds like she didn't "almost" steal your boat or "try" to steal your boat. She stole your boat. She'd effectively stolen the boat when she exited your slip with it.
Who knows if your DA will prosecute, but if you "almost" rob a bank, but don't get out of the parking lot with the loot, you'll do time for robbing the bank.
Whether she's crazy is another matter, but the boat was stolen IMO (I'm not an attorney, but I've watched a lot of Law and Order).