Biomechanical Assessment of Small Craft Collisions

Six staged watercraft collisions were performed to assess the corresponding boat dynamics and boat operator kinematics. Each boat was operated remotely through a series of handheld radio transmitters capable of controlling steering, throttle, and a master kill switch. The impact angles varied and the differences in traveling speed between the impacted (target) boat and the striking (bullet) boat just prior to impact was approximately 20 knots. Triaxial accelerometers mounted to the deck of each boat provided sensor data that was measured and recorded using several MotionMaster EDR-6DOF recorders. Hybrid-II anthropomorphic test devices (ATDs) were placed in occupant positions and their resulting kinematics recorded. Deck triaxial acceleration data was used as input to a lumped-mass human dynamics model (MADYMO) to understand occupant kinematics and potential for injury. Noted results include the presence of large vertical (z-axis) deck accelerations. Results were analyzed to assess expectations regarding occupant kinematics as a function of speed, attitude, positions of target and bullet craft, as well as boat design parameters. The role of grip strength in the ability of an occupant to hold on to available railings in the face of an imminent collision was assessed. The collision geometry was analyzed in terms of USCG Rules requirements and expectations regarding operation in extremis. Within the impact velocities and angles studied in this test series, results indicated a low risk of head and neck injuries during the first phase of the collisions.