We were at Lake Raystown, Pennsylvania. My wife was driving, my 4 year old son Rip and I were observing, and my dad was riding. When my dad's run was over we circled back to pick him up, and stopped with the swim platform a few feet from him. My wife didn't shut the boat off because, at the time, I had a bad plug on my engine coolant temperature sensor which made the motor hard to start when it was hot. I stood up and started pulling in the rope, and Rip went to the swim platform to "help" his grandfather by grabbing his gloves (yeah, he still wears 'em) and board, which Rip likes to do to feel more involved. After standing on the swim platform for about 10 or 15 seconds, Rip dropped to his hands and knees on the platform. I didn't like that with the motor running, so I slid over the sunpad, reached down, grabbed him, and put him down on the sunpad. When I put him down I didn't know anything was wrong, but when I looked at his face I knew something wasn't right. He was pale and looked super, super tired. I spoke to him in a loud voice, but he didn't respond, and his eyes looked dull. I picked him up, carried him to the observers seat, and put him down. Everyone - my wife, my dad, and me - tried to get him to say something, but he wouldn't respond and seemed to grow paler. Also, his breathing seemed to slow down, and his eyes began to close and open, close and open. It was absolutely terrifying. We were about 4 miles or so from the boat launch. My wife drove us there with the throttle pinned while my dad and I did the best we could with Rip. His breathing continued to slow (at least it seemed so to us), so my dad began to do mouth-to-mouth while I spoke to the 911 operator on my cell phone. Rip's breathing seemed to normalize a little, so my dad stopped the mouth-to-mouth, but it was all we could do to keep him awake. The ambulance met us at the boat launch. Rip was started on oxygen and taken to the hospital. The entire way there my wife had to actively keep him awake (I was in our car following the ambulance.) At the hospital, Rip was diagnosed with carbon monoxide poisoning (I forget what his blood level was, but the doctor said it was significant but never life threatening) and was treated with oxygen for about 7 hours. As the doctor predicted, thankfully Rip hasn't had any long term issues because of the exposure.
While we were at the hospital, my wife and I were interviewed by a Pennsylvania Fish and Game officer off and on for several hours. He was actually a really nice guy. He seemed to think that the air quality that morning may have played a role - it was super, super hot and humid, just really dense. Also, I remembered that a wake from a large boat rolled past us in the brief amount of time that Rip was on the platform (indeed, my dad had stopped riding because it was getting too rough) and he seemed to think that maybe the exhaust being lifted out of the water was a contributing factor as well. Since carbon monoxide can accumulate over time in the body, I think that because Rip went back to the swim platform a few times earlier that morning to "help" me and my wife he may have had some build up prior to the tipping point event with my dad.
I've made some changes since that day. If someone is on the swim platform or near the back of the boat, the motor is off, period. Also, I won't chill beside or near any other boats that are running. If conditions are right (or, rather, wrong) carbon monoxide poisoning can set in faster than you'd think, and when it does it is truly horrifying.