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The consideration of shallow water effects has gained in importance regarding inland operations. The interaction between the keel and the riverbed affects the hydrodynamic characteristics of marine vessels. The highly complex nature of the interference phenomenon in catamarans makes the shallow water problem more complicated as compared to monohulls. Hence, catamarans are very sensitive to speed changes, as well as to other parameters, such as the shallow water effects. This makes the design of catamarans more challenging than their monohull equivalents. At lower Froude numbers, the higher importance of the frictional resistance makes the greater wetted surface of the catamaran a disadvantage. However, at higher speeds, there is the potential to turn their twin hulls into an advantage. This study aims to investigate the wave-making resistance of a zero-carbon fast passenger ferry operating in shallow water. The URANS (unsteady Reynolds-averaged Navier–Stokes) method was employed for resistance simulations. Then, the double-body approach was followed to decompose the residual resistance into viscous pressure and wave-making resistance with the help of the form factors of the vessel calculated at each speed. The characteristics of the separated wave-making resistance components were obtained, covering low, medium, and high speeds. Significant findings have been reported that contribute to the field by providing insight into the resistance components of a fast catamaran operating in shallow waters. [ABSTRACT FROM AUTHOR]

Special demands in marine applications such as large capacities in transportation and fast deployment in military operations have brought multihull concepts forward. Open deck areas, high stability characteristics, and a wide range of operating speeds are some of the strong sides of these vessels. The fact that few studies have been done on manoeuvring performance predictions of these types of ships has been the main source of motivation in conducting this study. A fast multihull form, Delft Catamaran 372 (DC372), has been selected for computational fluid dynamics (CFD)-based system simulation application. CFD method has been subjected to a verification and validation (V&V) process using the latest solution verification techniques and available comparison data in the literature. The computerized planar motion mechanism (CPMM) approach has been applied to determine all the necessary hydrodynamic derivatives stated in Abkowitz's manoeuvring model. A new approach to analysis of manoeuvring performance of multihull vessels, discrete study of hull components (DSHC), has been introduced for the interpretation of manoeuvring coefficients. The dynamic manoeuvre system simulator (DynaMaSS) in which a waterjet and conventional steering/propulsion units (SPUs) are implemented, has been presented for the 20-degree turning circle (TC20) and 20/20 zigzag (ZZ20) manoeuvre simulations of DC372. The manoeuvring coefficients of DC372 have been determined at a satisfactory level by the CFD method. Successful results and solution strategies have been presented for DC372. • A complete study has been conducted on the prediction of hydrodynamic derivatives of a fast catamaran hull using the computerized PMM approach. • Turn and zigzag manoeuvres of a fast catamaran hull have been performed by implementing two different steering and propulsion units integrated into the dynamic manoeuvre system simulator (DynaMaSS) based on Abkowitz's model. • Discrete study on hull components (DSHC) approach has been introduced to be used in the assessment of multihulls' manoeuvrability in terms of understanding how each hull component contributes to the motion during a manoeuvre. [ABSTRACT FROM AUTHOR]

In this study, the acceleration and stopping manoeuvres of a bare hull surface combatant have practically been predicted by closed-form (analytical) solutions derived from basic mechanical principles. They have also been simulated directly by an unsteady RANS (Reynolds-averaged Navier-Stokes) solver with overset grid structure to compare the results with those of closed-form approaches. A well-known surface combatant model DTMB5415 has been chosen for validation. The instantaneous drag forces of the model ship in the acceleration and stopping manoeuvres have been provided by both CFD and Holtrop's methods. It has been observed that the results by analytical solutions have a good match with those of the manoeuvring simulations based on unsteady RANS solver. Successful predictions have also been made consistent with the results obtained when experimental resistance values are used in analytical solutions. It has been concluded that the closed-form solution methods yield practically satisfactory results in a very short time when a fast resistance prediction method, such as Holtrop's method or CFD, is used. • Analytical (closed-form) formulations have been derived for manoeuvre performance predictions. • CFD and Holtrop's method have been used to provide data to closed-form solutions. • The closed-form solutions yield fast results compared to direct simulations or experiments apart from being cost-effective. • Using experimental values in the present approach gives reasonably consistent predictions with those of direct simulations. [ABSTRACT FROM AUTHOR]