Working on a fisheries creel survey, 3 retirement age men with a Lund aluminum boat. Water level is below normal and they are towing with an old station wagon. Backed to the edge of the ramp,boat on sand at water's edge, hook electric winch to the bow eye. I'm about 100' away,watching the boat being winched up onto the roller trailer. 1 guy on each side and one running the winch, I can see the boat get pulled up tight to the winch post. Guy running the winch hasn't moved away and I can see the winch post start to flex, I yelled and started running their way. No one hears me and I watch the boat shoot off the trailer back into shallow water, motor up. The winch pulled the bow eye off and the the post sprung back, lucky no one was behind the boat. I helped them get it back on the trailer, then had to pull their car/trailer up the ramp with the state truck, trying not to laugh the whole time.