The present study focuses on the hydrodynamic hull form optimization of a zero emission, battery driven, fast catamaran vessel. A two-stage optimization procedure was implemented to identify in the first stage (global optimization) the optimum combination of a ship’s main dimensions and later on in the second stage (local optimization) the optimal ship hull form, minimizing the required propulsion power for the set operational specifications and design constraints. Numerical results of speed-power performance for a prototype catamaran, intended for operation in the Stavanger area (Norway), were verified by model experiments at Hamburgische Schiffbau Versuchsanstalt (HSVA), proving the feasibility of this innovative, zero emissions, waterborne urban transportation concept.

This paper numerically investigates the resistance at full-scale of a zero-emission, high-speed catamaran in both deep and shallow water, with the Froude number ranging from 0.2 to 0.8. The numerical methods are validated by two means: (a) Comparison with available model tests; (b) a blind validation using two different flow solvers. The resistance, sinkage, and trim of the catamaran, as well as the wave pattern, longitudinal wave cuts and crossflow fields, are examined. The total resistance curve in deep water shows a continuous increase with the Froude number, while in shallow water, a hump is witnessed near the critical speed. This difference is mainly caused by the pressure component of total resistance, which is significantly affected by the interaction between the wave systems created by the demihulls. The pressure resistance in deep water is maximised at a Froude number around 0.58, whereas the peak in shallow water is achieved near the critical speed (Froude number ≈ 0.3). Insight into the underlying physics is obtained by analysing the wave creation between the demihulls. Profoundly different wave patterns within the inner region are observed in deep and shallow water. Specifically, in deep water, both crests and troughs are generated and moved astern as the increase of the Froude number. The maximum pressure resistance is accomplished when the secondary trough is created at the stern, leading to the largest trim angle. In contrast, the catamaran generates a critical wave normal to the advance direction in shallow water, which significantly elevates the bow and creates the highest trim angle, as well as pressure resistance. Moreover, significant wave elevations are observed between the demihulls at supercritical speeds in shallow water, which may affect the decision for the location of the wet deck.

The present study deals with the local optimization of the stern area and of the propulsive efficiency of a battery-driven, fast catamaran vessel. The adopted approach considers a parametric model for the catamaran’s innovative transom stern and a QCM (Quasi-Continuous Method) body-force model for the effect of the fitted propellers. Hydrodynamic calculations were performed by the CFD code FreSCO⁺, which also enabled a deep analysis of the incurring unique propulsive phenomena. Numerical results of achieved high propulsive efficiency were verified by model experiments at the Hamburgische Schiffbau Versuchsanstalt (HSVA), proving the feasibility of the concept.

In this paper the hydrodynamic design procedure for Energy Saving Devices (ESDs) developed in the FP7 EU project GRIP is applied to full scale validation vessel – a newly built handymax Bulk carrier by Uljanik shipyard in Croatia. Three ESDs such as

This paper provides comprehensive numerical and experimental studies on the unsteady resistance of the world’s first battery-driven, zero-emissions high-speed catamaran, the MS Medstraum, in accelerated forward speed motion. These studies suggest that for a certain speed range of around Froude 0.50 (the so-called last hump of wave resistance), the corresponding unsteady resistance is significantly less than the originally anticipated value, namely, up to 40% less when adding to the steady resistance, the conventional added mass term. This surprising result could be explained by both experimental resistance tests and CFD calculations, as well as by inspection of the numerically generated wave patterns. Thus, care must be taken when applying the traditional approach to the unsteady resistance of a ship in accelerated or decelerated forward speed motion. As such, this positively affects the estimation of the required power capacity to accelerate the ship to full operational speed. This leads to reduced (fitted) battery weight and positively affects the ship’s displacement, allowing the vessel to achieve higher speeds. The present research finally yielded notable results of interest for seakeeping and ship maneuvering simulation studies; namely, comprehensive CFD simulations for the studied slender catamaran have shown that calculated added mass values for surge motion in real-flow conditions are up to six times higher than those initially estimated by ideal flow potential theory methods.