A prediction program of manoeuvrability for a ship with a gate rudder system

The Gate Rudder is a special twin rudder system with two rudder blades placed aside of a propeller. Main advantage of this system is the energy saving originated from the rudder thrust which is induced by the two cambered rudder blades comparably efficient to ducted propellers. However, as any rudder’s prime task, the performance of manoeuvrability is critical to the Gate Rudder too. With the currently available Manoeuvring Modelling Group (MMG) simulation programs, the simulation is only applicable to the traditional single rudder located behind the propeller. Therefore, how to predict the manoeuvring performance for the gate rudder is the focus of this paper. On the other hand, a recent study of the Gate Rudder reveals that this innovative system has remarkable flap effect which is well known as a manoeuvring interaction between rudder blades and ship stern. This phenomenon has been observed in the case of conventional rudder and introduced into an MMG-based theoretical model as interaction factor aH. However, the average values of aH for conventional rudder is between 0.1-0.2 in general whilst the aH value for the Gate Rudder is more than twice as much, showing a superior course keeping ability of the Gate Rudder. The paper presents the manoeuvrability simulation method of a ship with this Gate Rudder system and introduces some examples of comparisons between the model tests and free running tests which was conducted with 2.5 m ship model in the manoeuvring tank at Kyushu University, Japan

On-line ship performance monitoring system for biofouling and its control.

Ph. D. ThesisMarine biofouling has a significant impact on the overall hydrodynamic performance of a vessel. The literature shows that powering penalties for heavy fouled ships may reach up to 80% in the worst-case scenario, clearly resulting in higher operational costs and overall greater CO2 emissions. In the 1920’s, ship performance monitoring emerged as one of the most suitable means of estimating these effects using full-scale on-board measurements coupled with various analysis techniques. The primary difficulty of such method stands in differentiating the effect of biofouling from the effects of such disturbances as waves, wind, change of operating conditions and so forth. A deterministic approach to this problem employs physical laws to estimate the contribution of the most relevant disturbances and hence to ‘deduct’ them from the measured in-service resistance. However, very few deterministic Ship Performance Monitoring Systems (SPMSs) have been successfully implemented to estimate all the effects of hull and propeller performance monitoring with both a scrutinised uncertainty and state of the art standards. The present research investigates this knowledge gap. The main aim of this research is to develop a working on-line SPMS based on the first published deterministic performance analysis method dedicated to the measurement of the effects of hull and propeller fouling on ship performance. In achieving these aims, Newcastle University’s R/V The Princess Royal was employed as a development and testing platform of the prototype SPMS, proving to be one of the few applications on small-size vessels. Four Key Performance Indicators (KPIs) were developed to estimate the impact of biofouling on hull and propeller. A novel method to derive Cf is also proposed. The accuracy of the estimations provided by the SPMS developed on-board The Princess Royal was assessed conducting a comprehensive Uncertainty Analysis, which includes all data treatment stages, from acquisition to performance analysis.Sasaki-SMP fun

Ship performance monitoring dedicated to biofouling analysis: development on a small size research catamaran

This paper provides a description of the deterministic ship performance monitoring system developed and installed on Newcastle University's Research Vessel, The Princess Royal, for the estimation of the effect of hull and propeller fouling on the vessel's performance. The study revolves around the principle of data normalisation, both in its theoretical and practical aspects. A procedure for correcting weather and operational disturbances is introduced that takes into account plausible resources limitations. According to the needs emphasised by the normalisation process, the required onboard measurement system is described as it was implemented on the research vessel. A robust method to prepare the raw data for the analysis and suitable for all ship types and sizes is then proposed. A performance analysis method is finally defined using four different indicators of the vessel hydrodynamic performance. On-board measurements are presented and analysed according to the proposed methodology. Results show an increase in resistance of over 20% with extensive shell fouling and prove the effectiveness of the used method.</p