Evaluación integral de la estabilidad direccional de un bote inflable de casco rígido tipo RHIB de la Armada del Ecuador

Abstract

CONDITION FOR PUBLICATION OF PROJECT. Rigid-hull inflatable boats (RHIBs) are high-performance, unsinkable vessels with a stable, lightweight, fast, and seaworthy design. However, directional instability at 30 knots has been reported for a 6.5 m vessel operated by the Ecuadorian Navy during interception tasks in estuaries. Its design differs from standard outboard-powered RHIBs: the bow has vertical sides, and the stern accommodates a 335 HP water jet. In this study, transverse dynamic stability is evaluated using the hull load factor 𝐴𝑝⁄∇2⁄3 = 5.8, where 𝐴𝑝 is the projected area, obtaining values of 6.62 and 5.13 for the light and full load conditions, respectively. Additionally, the second criterion of the distance from the LCG to the centroid of the planing area, which depends on speed, was considered. This distance should not be less than 3% of the projected Chine length Lp, obtaining 0.09 and 0.01 for the first and second conditions, respectively. Regarding vertical stability, the calculated values were 4.08 and 4.06 for light and full load conditions, exceeding the limit established for vertical instability. Finally, the course keeping ability was evaluated using the Routh-Hurwitz criterion applied to the hydrodynamic coefficients, including the contribution of the appendages, which have a significant effect on the Yv and Nv coefficients at a speed of 30 knots. Keywords: boat, transverse dynamic stability; vertical stability; course keeping ability; criterion; appendages.