Characteristics of a series of high speed hard chine planing hulls - part II: performance in waves

An experimental investigation into the performance of high speed hard chine planing hulls in irregular waves has been conducted. A new series of models representative of current design practice was developed and tested experimentally. Measurements of the rigid body motions and accelerations were made at three speeds in order to assess the influence of fundamental design parameters on the seakeeping performance of the hulls and human factors performance of the crew, with an aim to provide designers with useful data. Response data, such as heave and pitch motions and accelerations, are presented as probability distributions due to the non-linear nature of high speed craft motions. Additionally statistical parameters for the experimental configurations tested are provided and the most relevant measures for crew performance discussed. Furthermore, an example of the use of these statistical parameters to evaluate the vibration dose value of the crew onboard a full scale high speed planingcraft is given. It is confirmed that at high speed craft motion leads to recommended maximum values of vibration dose value being exceeded after only short durations. In practice, therefore, mitigating strategies need to be developed and/or employed to reduce crew exposure to excessive whole body vibratio

A study of shock impacts and vibration dose values onboard highspeed marine craft

The shocks and impacts encountered on small high-speed craft exceed the limits set for safe working practice according to current standards. European legislation regarding the exposure to vibration will have far reaching effects on the operators of such craft with respect to the safety of their employees. This paper sets out to highlight the vibration dose values that can be expected during typical transits onboard high-speed craft and attempts to clarify some of the controversy currently surrounding vibration dose measurement in such circumstances. In order to relate vibration dosage to the impacts encountered and to boat motion, an algorithm was developed that identifies the timing and magnitude of impacts

Race-time prediction for the Va’a paralympic sprint canoe

The 2016 Paralympic Games in Rio de Janeiro will see 200m sprint canoe events for the first time, using the Va’a class. The aim of this study is to predict race times for the Va’a over a 200m sprint event, through simulation of the hydrodynamic resistance of the hull (with outrigger) and the propulsion provided by the athlete. Such a simulation, once suitably validated, allows investigation of design and configuration changes on predicted race performance. The accuracy of the simulation is discussed through a comparison to times recorded for an athlete over a 200m race distanc

The effect of swimsuit resistance on freestyle swimming race time.

It is known that swimming equipment (suit, cap and goggles) can affect the total resistance of a swimmer, and therefore impact the resulting swimming speed and race time. After the 2009 swimming world championships (WC) the international swimming federation (FINA) banned a specific type of full body suit, which resulted in an increase in race times for subsequent WC events. This study proposes that the 2009 suits provided a reduction in swimming resistance and aims to quantify this resistance reduction for male and female freestyle events. Due to the practical difficulties of testing a large sample of swimmers a simulation approach is adopted. To quantify the race time improvement that the 2009 suits provided, an equivalent 2009 “no-suit” dataset is created, incorporating the general trend of improving swimming performance over time, and compared to the actual 2009 times. A full race simulation is developed where the start, turn, underwater and surface swimming phases are captured. Independent resistance models are used for surface and underwater swimming; coupled with a leg propulsion model for underwater undulatory swimming and freestyle flutter kick, and a single element arm model to simulate freestyle arm propulsion. A validation is performed to ensure the simulation captures the change in swimming speed with changes to resistance and is found to be within 5% of reality. Race times for an equivalent “no-suit” 2009 situation are simulated and the total resistance reduced to achieve the actual 2009 race times. An average resistance reduction of 4.8% provided by the 2009 suits is identified. A factor of 0.47 ± 10%, to convert resistance changes to freestyle race time changes is determine

Hydroelastic inflatable boats: relevant literature and new design considerations

Inflatable boats are considerably more flexible than conventional metal or composite vessels. The RNLI have developed an inflatable boat, the IB1, with improved performance which has been attributed to its flexibility or hydroelasticity. Current design methodologies for planing vessels predict the performance assuming it is rigid. Designing an entirely hydroelastic boat presents completely new design challenges and will require new design methodologies in the future. This paper considers how to approach an entirely hydroelastic planing vessel and how to divide the boat into practical problems. A design approach taking into account hydroelasticity could potentially improve the performance further by decreasing boat motions, reducing added resistance in waves and minimising the slamming accelerations. This paper reviews the literature relevant to rigid inflatable and inflatable boats and shows the construction of the IB1. The hydroelastic design problem is broken down into three main hydroelastic events: global hydroelasticity, hydroelastic planing surfaces and hydroelastic slamming. Each event is defined, the relevant literature is reviewed and the possible advantages are discussed. A design approach is suggested using a hydroelastic design cycle. The hydrodynamic problem of interacting sponsons is briefly discussed. <br/