In a recent boat accident, a 25-year-old yachting enthusiast fell overboard and survived for 24 hours in 17 degrees C water. Existing survival models are discussed in this case report. There is a discrepancy regarding survival probability amongst the various models. The calculated survival time for the yachtsman ranges from 3 hours to more than 30 hours. A reliable survival-time model is needed to determine the appropriate search duration of rescue services. In this case, the majority of the models underestimated the actual survival time.