The Royal National Lifeboat Institution (RNLI) charity works to “save lives at sea” across the United Kingdom and Ireland. Rescuing 23 people a day, this institution owns the largest fleet of inflatable boats (IBs) and rigid inflatable boats (RIBs) in the United Kingdom.
Ocean waves cause almost all high-speed planing vessels, including IBs and RIBs, to vibrate in a nonlinear manner called “boat motion,” which is one major cause of long- and short-term injuries with physiological and psychological effects for the crew. The RNLI needed a new strategy to reduce human exposure to these harsh vibrations.
For this project, the University of Southampton studied the RNLI D-class IB by performing four full-scale experiments—stationary tests, drop tests, flat water trials, and wave trials—each affecting a different aspect of hydroelasticity. Boat motion was measured using 52 sensors through 74 channels attached to various parts of the boat. The analog signals were converted from these sensors into digital signals and were saved during each experiment.
To increase reliability, simplify coding, and reduce compilation time, a rugged and reliable data logger flexible enough to accommodate a wide variety of sensors was needed. Additionally, a stand-alone system small enough to fit inside a waterproof case in a restricted space was essential. The cRIO-9074 integrated system met these
requirements and could be reconfigured into a data logger. With a variety of C Series modules, the University of Southampton could wire almost any signal into the CompactRIO system. Coding for this data logger was developed using LabVIEW software, making programming simple and fast.
The CompactRIO system was robust and rugged enough to simultaneously measure performance and deformation and save the data while under extreme conditions. The University of Southampton’s next step is to link performance and deformation together to find the origin of the effect of hydroelasticity and isolate the components dominating this effect.