I've got two.

1. Lake Lewisville Texas at Pier 121 4 or 5 years ago. A lady comes pulling up to the old gas dock in a big Carver, 40+ ft., flying bridge, the works. At about 30 feet from the dock she is coming in hot but at this point it was still a salvageable situation, she's hot but her angle is pretty good. Things then go from squirrelly to scary as she decides to kill the engines. I'd say she crashed into the gas dock at 5 or 6 mph in what must have been a 25,000 pound boat maybe more. The boat was really screwed up, the kids working the gas dock thought their lives were over. Connected to the old gas dock was a walkway flanked by drive in boat slips for the restaurant which is just down from the old gas dock. It's 50/60 or so feet from the gas dock to the restaurant drinks food and all manner of stuff flew off off tables onto the floor. People were literally screaming.

2. Same lake earlier this year sixty feet from my slip. Set up, dude buys a 42' cruiser, part of the deal is that the selling dealership will pay for slippage for 6 mos. The dealer makes the boat delivery on an extremely bad weather day, slips the boat, delivers the keys to the owner's home, and promptly forgets to pay the marina for the slippage. A few days later the owner shows up - unties the boat - gets in - starts it up - feels the elation as the boat moves forward, about four feet and it stops. He gives it some more throttle nothing but noise, more throttle still more noise.
He thinks crap I missed a line so he kills it walks around the deck and sees no lines. He gets back in fires it up and gives it a lot of gas.

This is the point where I hear a lot of motor noise, fiberglass ripping and metal screeching. And the boat rises by the nose and then crashes down and leaps forward.

The marina had put a security cable in front of the boat. The owner, who I now know a little and is a really nice man, just flat out didn't see it. His insurance man said it cost $135K to fix all the damage.