This work was performed at Webb Institute along with Dan Roske as part of our undergraduate degree.
Introduction
Trim tabs and interceptors are two devices used on high-speed planing craft to lower resistance at pre-planing speeds, as well as to decrease motions in waves. These devices work by creating lift near the transom. Dan and I used a model hull fitted with a 3D-printed pressure sensor manifold to measure the pressure distribution created by these devices, while also measuring resistance. We used our results to comment on the effectiveness of the two devices, as well as the accuracy of empirical methods used to predict the performance of these devices.
Testing
A hull was modified to add a pressure sensor array which was designed and 3D printed for this testing. 11 pressure sensors were used to allow fine measurements of the pressure near the transom of the hull. Three sets of trim tabs were 3D printed, as well as a single interceptor plate with variable deployment.
Testing was done at both Webb Institute’s Robinson Model Basin and Stevens Institute of Technology’s Davidson Laboratory. Tests focused on the pre-planing speeds, where transom lift devices are known to be the most useful at decreasing resistance.
Results
Through our testing, we were able to measure the longitudinal pressure distribution with higher resolution and precision than earlier work. We compared our measurements to the operating principals of interceptors and trim tabs, and to performance prediction methods. From these comparisons, we made suggestions for improvements to current performance prediction methods. Additionally, we were able to observe that both interceptors and trim tabs have similar speed regimes of effectiveness.
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