I saw an engine run away in a 63ft Ocean sportfish. I think it was a 12V92TI or it might have been a 16V92TI. The owner was coming into the harbor at wot, when he went to pull back the throttles the port engine would not come down. Now keep in mind he was a novice boater who had just bought the boat, and he was heading into a crowded harbor at 30+ knots, he was about 1 1/2 miles off the at the time. He also tried the emergency shut off's but they didn't work for some reason. Well insted of turning the boat around and heading back out to figure out the problem. He decides to take it out of gear!!!
Now we are talking about a diesel running at 110%, now with no load, my god that thing smoked and made noises diesels shouldn't make! Black smoke was pouring out of the exhuast, the boat looked like it was on fire! I was about 1/2 a mile off it at the time. It seemed like a long time but probably no more than a minute the engine self destructed and went silent. The police etc came out but the Ocean did go in under it's own power. My dads friend is a diesel mechanic, he had just finished majors on this boat the month before. He was called back and basically came to the conclusion the engine was shot, it sucked the turbo in! Rods and valve peices were everywhere he said. What a mess, but nothing $100k couldn't fix. I don't remember what failed a fuel valve of some sort. In hindsight the boat only had a couple hundred gallons of fuel on board he should have pulled the starboard engine back and let the port suck the fuel dry.