Wave impact loads on wave-piercing catamarans

Abstract

Wave slamming is investigated for the 112 m INCAT wave-piercer catamaran with reference to experimental work conducted at full scale, numerical computation by CFD and FEA and testing at model scale using a 2.5 m segmented hydro-elastic model. The segmented model was tested in regular head seas to investigate the magnitude and location of the dynamic wave slam force and slam induced hull bending moments. The model consists of rigid segments joined by elastic hinges designed to match the scaled first longitudinal modal (whipping) frequency measured at fullscale on the INCAT 112m vessel. Effects of forward speed and wave encounter frequency on slamming and whipping were investigated. Scaled slam forces of up to 2150 tonnes weight (21.1 MN) were measured during model tests for a full-scale vessel with a loaded displacement of 2500 tonnes. These slams can impart impulses on the bow of up to 938 tonne weight-seconds (9.20 MNs) and strain energy of up to 3.5 MJ into the ship structure based on scaled model test data. The impact energy is transferred primarily to the main longitudinal whipping mode, which decays with an overall structural damping ratio of 0.02 to 0.06, this being strongly dependent on internal frictional mechanisms within the ship structure.

H2/H∞ Antivertical Controller Based on Particle Swarm Optimization (PSO) Using Active T‐Foils and Trim Tabs for a Fast Catamaran

“…Further, because a catamaran is much wider than a single-hull vessel, it has relatively much higher lateral stability. Finally, under adverse sea conditions, it shows ∼15% lower roll angle and can withstand large waves; these are useful characteristics in practice [3].…”

Wet-deck slamming loads and pressures acting on wave piercing catamarans

“…Improving the seakeeping performance of high speed catamaran ferries was one of the earliest development stages of these vessels [1][2][3][4]. For WPC vessels, the role of centre bow is to provide reserve buoyancy in the forward area [5,6] where the demi-hulls are extremely slender to restrict pitch motions in extreme pitch-in scenarios. Therefore WPCs are less prone to deck-diving than conventional catamarans with a flat cross-deck bow structure [7,8].…”

“…If slamming cannot be avoided, the calculation of arch slamming pressure and evaluation of structural design with respect to the vessel's operational conditions are necessary for class approvals [11]. However, it should be noted that the WPC design does virtually prevent deck diving which can lead to far more serious damage [5,7].…”

Slam loads and pressures acting on high-speed wave-piercing catamarans in regular waves

“…For general ship slamming many are reviewed by Kapsenberg [8] and Hirdaris et al [9]. In WPCs experimental techniques have been used extensively for the identification of slam loads, including drop tests [10][11][12], scale model tests [13][14][15][16][17] and full scale trials [18,19], along with several numerical investigations, for example [20,21]. Davis and Whelan [10] systematically studied CB geometry in drop tests, recommending modifications to bow flare angle and archway clearance of Incat catamarans to reduce the slamming pressures over the impact area.…”

“…The segments have tuned elastic connections to properly account for hydroelasticity. Segmented models have been used in many studies on various types of ship for the measurement of vertical bending moments, shear force, slam-induced structural vibratory response (whipping) and identification of slam loads [1,14,16,[22][23][24][25][26][27][28][29].…”