Experimental validation of spray deflectors' impact on performance of high-speed planing craft

High-speed planing craft is designed to overcome conventional hull’s speed barrier associated with wave making resistance and high frictional forces. Despite being able to reach high speeds, some planing hull forms will develop large volumes of spray attached to the hull surface, which can account for a large proportion of the total resistance. In this study, an experimental evaluation of the novel spray deflector technology proposed by Petestep AB is carried out in model scale at the Davidson Laboratory towing tank. The spray deflectors are compared against a time-proven spray rails technology and bare hull configuration. A modular hull design was developed that allows for rapid conversion between the three hull configurations and for future modifications to the design. The calm water resistance tests have shown up to 9\% resistance reduction for spray rails and up to 25.75\% reduction for spray deflectors as compared to the bare hull configuration. The running position of the spray deflector configuration was affected by the selected deflector design and differed from the spray rail and bare hull configuration, making the direct comparison of the technologies inapplicable. The irregular waves tests have shown that for the current deflector design, the significant accelerations are approximately the same for the spray rail and spray deflector configurations. Both the technologies have led to increased accelerations at the center of gravity as compared to the bare hull. The spray deflector configuration, however, experienced lower accelerations in the bow area. A number of improvements to the current model design were proposed for the next series of experiments