I've only had one encounter with hypothermia - last spring. I wanted to get an early start to the kayaking season, so I headed to the put-in on the first 50 degree day in April. The forecast was for sun most of the day, so I took my wetsuit and drytop, but no additional layers. I swam out of my boat after flipping in the first class III rapid. My paddling partners corralled my boat, and I swam to shore with my paddle. The air may have been 50 degrees, but the snowmelt-fed river was still well under 40. I was able to get back into my boat, but was shivering pretty badly. Half an hour later, I flipped and swam in another rapid. At this point, I could barely get the skirt back onto my boat.

I could barely hold on to my paddle, and I could tell I wasn't responding anywhere near as fast as usual. Luckily, my paddling partners convinced me to get off the river. I stopped at the next possible takeout, hiked up to the road, and hitchhiked back to the put-in and my car. My partners made sure I got a ride, and then completed the run.

In hindsight, I was stupid to expect sunny weather, no matter what the forecast said - it rained all day. I was also very underdressed for the conditions. I did choose good paddling partners, who were willing to chase lost gear down for me and convince me to get off the river instead of encouraging me to "tough it out."