| TBDP© Porpoise Regime Analysis | (click on screen to return) | |
| BREAKTHROUGH! | ||
 Figure 1- TBDP® graphic output shows the velocity at which a tunnel hull configuration experiences instability in Porpoise Regime and susceptibility to porpoising. |
We have developed a new analysis tool in the TBDP®/VBDP® software! XPorpoise is an engineering tool developed by AR® that
helps predict your hull's inherent
instabilities leading to porpoising. The technique is
based on a unique Savitsky method of hydrodynamic
prediction of the critical porpoise trim angle (CPA) for
various hull/setup configurations, velocities and Lift
characteristics. Porpoising onset occurs when the lift is generated at a sufficiently high trim angle or sufficiently low deadrise so as to cause a dynamically unstable loading on the lifting surfaces. By analysis of a hull's design and performance characteristics and comparison to the CPA for each velocity in performance range, TBDP®/VBDP® can predict when the hull is susceptible to porpoising and when it is performing in a stable regime. |
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The XPorpoise is presented in standard TBDP® and VBDP® output and in graphic analysis format. It's simple to interpret when the hull is in the "Porpoise regime" or in the "Stable regime"....AND simple to change setup or design features with TBDP V7.10 to make the hull less susceptible to porpoising. |
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 Figure 2 - VBDP® graphic output shows the differences in vee hull bottom designs that can contribute to instability in Porpoise Regime and susceptibility to porpoising. |
TBDP®/VBDP®
analyzes the porpoising stability of your hull design/setup throughout the
entire operating velocity range.
TBDP®/VBDP®
then presents the analysis for your design for operation in "stable planing
regime" or "Porpoise instability regime".
When your hull is in the
"stable planing range", the hull is less likely to experience porpoising.
When your hull is in the "Porpoise instability regime", it is
susceptible to
porpoising. The ability for TBDP®/VBDP® to present graphic view of XPorpoise analysis throughout the full operating velocity range, for TWO design alternatives simultaneously, makes comparative evaluation quite easy. (Note view in Figure 2 that shows "shallower deadrise with pad" vee hull, compared to "steeper deadrise, no pad" vee hull designs - and their relative susceptibility to porpoising in "Stable Planing" regime (less susceptible to porpoising) or "Porpoise Regime" (more susceptible to porpoising). |
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TBDP®/VBDP® makes it easy to see the performance and stability improvements that are achieved by design modifications and/or setup changes - and improvements to the porpoising phenomenon! |
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