Recreationally is a toss up but both on my grandparent's old 1948 46' Chris Craft DCFB. First one was the last time he hauled out at the marina at the head of the river. That moron was supposed to lower the railway trolley down just enough to soak the hull so it had time to let the wood swell. Instead he completely launched us off into the river. Committed at that point, so started the engines and got moving. We steadily went down, made it about halfway home and had to beach it. Tide went out, she was high and dry; tide came back in that evening and she was floating nicely like nothing ever happened. The other time was sitting at a marina on another river because the engines wouldn't start. Two of my uncles (mind you I have four who all consider themselves mechanics and zero actually are) show up. Their grand idea is to keep pouring gas down the carb throats (twin 413's) instead of troubleshooting WHY they weren't getting fuel. One time one of them got lazy and didn't put the flame arrestor back on. That's when it backfired, ignited and we found out that the installed fixed CO2 system actually worked. Singed couch and one uncle with burned feet who went overboard immediately. Then a real mechanic showed up and figured out fairly quickly that the fuel filter seals weren't sealing and sucking air.
Professionally, dozens of shipboard fires, almost getting launched into the water during a towing evolution, smacking a large propeller repeatedly into a coral reef, blowing up a generator, losing power & propulsion and coming dangerously close to running into an aircraft carrier.....nothing catastrophic to life and limb but definitely contributing to bad days.
