Water Intrusion Injuries: Occupant Kinematics and Pressure Exposure during Rearward Falls from a Personal Watercraft

Personal watercraft (PWC) users and other high-speed watersports participants have sustained rectal and vaginal injuries during falls into the water, herein referred to as water intrusion injuries (WIIs). WIIs result from the rapid introduction of water into these lower body cavities causing injury to the soft tissues of the perineum, rectum, and vagina. While case studies of injured water-skiers and PWC users are reported in the literature, there is little information related to passenger kinematics and pressure exposure during a rearward fall from a PWC. The results of an experimental study of passenger falls from two “high-performance” PWC are presented herein. A human passenger was caused to fall rearward as the PWC was accelerated at maximum throttle starting from idle speed (≈3–4 mph) and planing speeds of ≈20–30 mph. The subject passenger fell from the aft seat position and while standing on the rear platform. Aerial and shore-based cameras were used to document passenger kinematics and separation from the PWC. Each PWC was equipped with onboard sensors, and the test subject wore an array of three pressure transducers secured to his perineal region to measure the pressure pulse during water entry. Peak pressures varied from test to test and the maximum pressures measured were on the order of 50 psi for a very short duration. Overall, the pressure pulse duration was on the order of 100 milliseconds. The passenger’s perineal region initially contacted the water approximately 1.4 feet (seated, idle speed) to 4.9 feet (standing, idle speed) aft of the PWC nozzle. When the passenger contacted the water, the PWC had accelerated such that the relative velocities between the passenger and PWC were ≈7–10 mph. The PWC and passenger separated rapidly, having attained 7–16 feet of separation within a quarter of a second after the passenger contacted the water.