, 2008), providing additional helmsman training (as Helmsman’s throttle and steering control has a significant effect on the motion Nieuwenhuis, 2005, Coats and Stark, 2008 and Townsend et al., 2008) and/or fitting suspensions seats. Anecdotal evidence suggests that suspension seats restrict crew movement, add weight and reduce craft feedback (which could lead to boat mistreatment, damage or dangerous driving). To the
authors’ knowledge no ride control systems for small high speed craft Proteasome inhibitor are commercially available. Furthermore, speed restrictions are not considered a realistic option for military and some rescue applications. While Helmsmen’s throttle/steering control is not infallible, particularly during night-time transits. In an attempt to address the issues of WBV and repeated shock for high speed craft operations, this paper examines the motion mitigation provided by various ‘flexible’ hull systems during a slam event. Such systems by reducing the impact on the entire craft could reduce the structural strength requirements and therefore vessel mass and cost. In addition to reducing the need for isolation mountings for sensitive, e.g., electronic,
equipment. As an initial appraisal of flexible hull design, the interaction between a high speed craft hull, seat and human occupant was modelled as a forced, multiple-spring–mass–damper-system as depicted in Fig. 2. The equations of motion describing Fig. 2 were modelled as equation(1) click here F1F2F3=m1000m2000m3x¨1x¨2x¨3+c1+c2−c20−c2c2+c3−c30−c3c3x˙1x˙2x˙3+k1+k2−k20−k2k2+k3−k30−k3k3x1x2x3where the subscripts 1, 2, 3 refer to the hull, seat and
human components respectively and m, c and k represent the system mass, damping and restoring coefficients respectively. The human body and seat model were based on the mass, damping and stiffness coefficients presented in Coe (2011) and Coe et al. (2009) respectively. The seat representing a typical suspension seat, e.g., a STIDD suspension seat. In this study, the hull mass (m1) was assumed constant and the damping (c1) and stiffness (k1) coefficients were varied. F2 and F3 Arachidonate 15-lipoxygenase were assumed zero. To represent a slam event F 1 was modelled as a symmetrical, smooth impulse force; equation(2) F=−Fae−(t−tp)2/2σ2F=−Fae−(t−tp)2/2σ2where F a, the forcing amplitude was calculated as the hull mass multiplied by 50 m/s2, a typical slam acceleration ( Townsend, 2008). t and t p represent the time and the time at which the peak force occurs and σ2σ2, a constant proportional to the impulse force duration, was assumed to be 0.0001. The motion responses, modelled in MATLAB based on the fourth order Runge–Kutta integration scheme, are presented in Fig. 3 and Fig. 4. For the given parameters, the simplified model shows that hull stiffness has a negligible effect on the motion response of a seated human.