Numerical modelling of structure responses for high-speed planing craft in waves

The paper presents an approach for time-domain simulation of structure responses, along with hydromechanic and structure inertia loads and motions responses, for high-speed planing craft in waves. Hydromechanic loads and motion responses are calculated with a non-linear time-domain strip method. A pressure shape function is introduced which enables formulation of detailed slamming pressure distributions sequences from the section forces in the strip method simulations. Structure responses are calculated quasi-dynamically by applying the momentary distributed pressure loads on a global finite element representation of the hull structure with use of inertia relief. From the time series output extreme responses are determined by means of short-term statistics. Promising results are demonstrated in applications on a high-speed planing craft, where extreme values of simulated structure responses are compared with responses to uniform design pressures from classification rules and measured responses from full-scale trials. The approach is concluded to be a useful tool for further research which has potential to form the basis for establishment of a computationally efficient simulation-based design methodology. A corresponding experimental modelling approach is presented in a parallel paper

Crew acceleration exposure, health and performance in high-speed operations at sea

The presented research program investigates the association between working conditions aboard High-Speed Craft (HSC) and its outcomes in terms of acceleration exposure and crew health and systems performance respectively. The aim is to identify the related risk factors and further, to use them to improve the assessment criteria in a simulation-based-design framework. The investigation initially document a seaborne population by a web-based questionnaire tailored for High-Performance Marine Craft Personnel (HPMCP) and similar populations. Then data is collected during regular service by measuring craft acceleration and through another questionnaire especially resolute on perceived work-exposure, health and performance. Exposure and performance data is collected daily and health data weekly, depending on seaborne frequency. The population repeats the prevalence questionnaire about a year later enabling a longitudinal follow-up for identifying long-term effects of exposure. The paper reports the two questionnaires´ development and pilot test as well as the first application for baseline data collection in the target group. The results indicate health and performance characteristics of the study population and data shows a promising correlation between the self-reported subjective exposure and the measured objective acceleration. Data indicates a comparatively higher prevalence of musculoskeletal pain in the study population than that of the general population

Crew acceleration exposure, health and performance in high-speed operations at sea

The presented research program investigates the association between working conditions aboard High-Speed Craft (HSC) and its outcomes in terms of acceleration exposure and crew health and systems performance respectively. The aim is to identify the related risk factors and further, to use them to improve the assessment criteria in a simulation-based-design framework. The investigation initially document a seaborne population by a web-based questionnaire tailored for High-Performance Marine Craft Personnel (HPMCP) and similar populations. Then data is collected during regular service by measuring craft acceleration and through another questionnaire especially resolute on perceived work-exposure, health and performance. Exposure and performance data is collected daily and health data weekly, depending on seaborne frequency. The population repeats the prevalence questionnaire about a year later enabling a longitudinal follow-up for identifying long-term effects of exposure. The paper reports the two questionnaires´ development and pilot test as well as the first application for baseline data collection in the target group. The results indicate health and performance characteristics of the study population and data shows a promising correlation between the self-reported subjective exposure and the measured objective acceleration. Data indicates a comparatively higher prevalence of musculoskeletal pain in the study population than that of the general population

Experimental modelling of local structure responses for high-speed planing craft in waves

The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft

KGmax curves associated with second generation intact stability criteria for different types of ships

Currently, second generation intact stability criteria are being developed and evaluated by the International Maritime Organization (IMO). In this paper, we briefly present levels 1 and 2 assessment methods for the criteria of pure loss of stability and parametric roll failure modes. Subsequently, we show the KGmax curves associated with these criteria. We compute these curves for five different types of ships and compare them with the curves embodied in the current regulations. The results show that the safety margin ensured by the first level-1 method of calculation for both pure loss of stability and parametric roll seems to be excessive in many cases. They also show that the KGmax given by the second level-1 method and by the level-2 method may be very similar. In some cases, the level-2 method can be more conservative than the second level-1 method, which is unanticipated by the future regulation. The KGmax curves associated with parametric roll confirm that the C11 container ship is vulnerable to this failure mode. The computation of the second check coefficient of parametric roll level 2 (C2) for all possible values of KG reveals the existence of both authorized and restricted areas on the surface formed by both the draft and KG, which may replace the classical KGmax curves. In consequence, it is not sufficient to check that C2 is lower than the maximum authorized value (RPR0) for a fixed ship’s loading condition