Sailing Yacht Research Articles

Unsteady Upwind Aerodynamics of a Sailing Yacht

_ Sail aerodynamics has been a researched topic since the start of competitive racing, such as the America's Cup and Whitbread Round the World Race. Recently, with restrictions on the use of wind tunnels and towing tanks in the America's Cup, there has been an increase in computational fluid dynamics (CFD) to study the aerodynamics and performance of yacht sails. These studies typically model steady-state conditions, but in contrast, this paper demonstrates the implementation of dynamic wind conditions in Reynolds Averaged Navier Stokes CFD and the effects it has on the aerodynamics of a yacht sailing upwind. A user-defined function was used to give a velocity profile and vary the wind direction with time to simulate a gust condition with a period of 10 s. In addition to the gusting model, steady models were run for the apparent wind angles (AWA) experienced in the gust to see if the dynamic wind conditions could be modelled by a series of steady state snapshots. The results show minor differences in the streamlines of two models and the pressure distributions show no significant difference. There is only a slight difference in sail forces at high AWAs. Although further research would be required this information could be valuable to anyone using CFD to test sail designs. Keywords CFD; transient; steady; upwind; UDF; RANS

Preface: Special Issue on Probing the Open Ocean With the Research Sailing Yacht Eugen Seibold for Climate Geochemistry

Preface: Special Issue on Probing the Open Ocean With the Research Sailing Yacht <i>Eugen Seibold</i> for Climate Geochemistry

A multi-criteria approach for comparing alternative fuels and energy systems onboard ships

This paper aims to present the upgrade of the Helper for Energy Layouts in Maritime applications (HELM) software tool, developed by the authors to compare traditional and innovative systems for energy production and storage onboard maritime vessels. The algorithm adopts a multi-criteria method and it carries out the analysis on a large and updated database of market solutions. A wide range of maps is implemented in the tool, correlating costs, volumes, weights, emissions and fuel environmental hazards with energy demand, applicative scenario and vessel type. The equations implemented in the software and the algorithm employed to evaluate and compare the technologies are reported. In this work, four different vessels are investigated, namely: (i) a small sail yacht; (ii) a small passenger ferry for inland water navigation; (iii) a large cruise ship; (iv) a large container ship. For each case study, the choice of the best solution is performed, considering the constraints, the inputs and the single parameters: in all cases, the solution chosen corresponds to the real one installed on board or to a solution that is going to be installed. It is worth noting that the multi-criteria analysis has a general approach, allowing to give preliminary information on the best energy system solution, also to comply with the application requirements (i.e. pollutant emissions in ports and restricted areas).

Combining Analytical Models and Mesh Morphing Based Optimization Techniques for the Design of Flying Multihulls Appendages

Abstract The fluid dynamic design of hydrofoils involves most of the typical difficulties of aeronautical wings design with additional complexities related to the design of a device operating in a multiphase environment. For this reason, “high fidelity” analysis solvers should be, in general, adopted also in the preliminary design phase. In the case of modern fast foiling sailing yachts, the appendages accomplish both the task of lifting up the boat and to make possible upwind sailing by contributing balance to the sail side force and the heeling moment. Furthermore, their operative design conditions derive from the global equilibrium of forces and moments acting on the system which might vary in a very wide range of values. The result is a design problem defined by a large number of variables operating in a wide design space. In this scenario, the device performing in all conditions has to be identified as a trade-off among several conflicting requirements. One of the most efficient approaches to such a design challenge is to combine multi-objective optimization strategies with experienced aerodynamic design. This paper presents a numerical optimization procedure suitable for foiling multihulls. As a proof of concept, it reports, as an application, the foils design of an A-Class catamaran. The key point of the method is the combination of opportunely developed analytical models of the hull forces with high fidelity multiphase analyses in both upwind and downwind sailing conditions. The analytical formulations were tuned against a database of multiphase analyses of a reference demihull at several attitudes and displacements. An aspect that significantly contributes to both efficiency and robustness of the method is the approach adopted to the geometric parametrization of the foils which was implemented by a mesh morphing technique based on Radial Basis Functions.

Utilization of GPS Technology in The Maritime Sector on Motor Sailing Yachts

The utilization of technology only aims to be fast, precise, and accurate in each implementation and find a better solution at that time in several sectors. This study aims to identify the use of Global Positioning Technology (GPS) technology to track the position of the motor sailing yachts, specifically with the features used on a device or smart-phone during a trip or expedition. This research uses a type of applied research to solve problems that are faced clearly, and the results can be used as a basis for solving corrective steps. The results found that GPS-Technology on motor sailing yachts in "Pelayaran Rakyat" maritime can receive coordinates point and then send these coordinates to the vessel-tracking systems to determine the position of the motor sailing yachts between users.

Course-keeping assessment of yachts’ upwind sailing in waves

A method for the efficient prediction of the course-keeping capability of sailing yachts in upwind sailing is presented, based on an integrated modular aero- and hydrodynamic model. The transient aerodynamic forces on the sails are calculated via the lifting surface theory and in particular the vortex lattice method for unsteady flows. The varying character of these forces due to sail shape deformation is accounted for via a finite element scheme for thin shells that is coupled to the force calculation module. The sails’ solver is coupled further to a potential flow solver for yacht hydrodynamics in waves combining panel and strip theory approaches and accounting for the instantaneous waterline. The integrated model can predict the motions in 6 degrees of freedom. Several maneuvering scenarios of the yacht are investigated by using the new model and conclusions are drawn for the operability limits of a cruiser yacht sustaining bow-quartering regular waves and unidirectional wind, with respect to maintaining, in the mean, the desired upwind heading. More specifically, course stability diagrams are produced for two types of course-keeping scenarios: in the first, the yacht performs tacking maneuvers; while in the second, the yacht is tried to maintain a prescribed constant heading with minimum corrections. The paper includes a comprehensive review of the state-of-art in order to demonstrate the niche of the proposed approach.

Study on Modularization of Components for Cost Reduction of Sail Yacht Steering System

This study aims to improve the price competitiveness of a steering system with a relatively high cost portion among sail yacht components. Hence, the components of the steering system were analyzed, and steering system modularization was proposed. The fabrication processes before and after the application of modularization was presented. For modularization, primary components such as the pedestals and quadrants of the steering system were developed, and the structural safety of the components was reviewed. It was confirmed that the manufacturing cost of the developed steering system decreased by approximately 33% compared with the existing system. The new steering system presented herein is expected to contribute to the localization of components and price competitiveness of sail yachts.

Science of the 470 Sailing Performance

This paper holds a significant place in the Journal of Sailing Technology, as the very last publication of Prof. Masuyama, published posthumously, and co-authors by Dr. Ogihara. For many decades, Prof. Masuyama has been a very influential and respected member of the sailing yacht research community world-wide, holding the chairmanship of the Sailing Yacht Research Association of Japan for close to 20 years, and being involved with the Japanese America’s Cup Challenge. His expertise and academic research have impacted generations of researchers, and his work on high performance sails, sailing yachts and velocity prediction remains at the forefront of sailing technology. It is therefore with great honour that the Journal of Sailing Technology presents the very last insights of Prof. Masuyama into the sailing performance of the 470 Olympic class dinghy.

Experimental and numerical wind tunnel investigation of the aerodynamics of upwind soft sails

The present paper reports an experimental/numerical study about the aerodynamics of sails in upwind conditions. This work is part of a wider research frame carried out in the recent years at Politecnico di Milano, involving numerical, wind tunnel and full-scale studies on the aero-hydrodynamics of sailing yachts. The experimental apparatus adopted in this work is the scaled-version of the full-scale setup adopted in the Sailing Yacht Laboratory (SYL) at the same institutions. More specifically, soft sails were tested in wind tunnel in close hauled conditions, properly equipped with thin and soft pressure strips at different sections of head and main sail. Therefore, simultaneous data about distributed pressure, aerodynamic forces and 3D flying shapes were gathered. Fine trimming were investigated during the tests to study the different effect on pressure distribution, performance and sail shapes. The measured sails geometry about the same conditions, fed the steady numerical simulations, based both on Vortex Lattice Method and Reynolds Averaged Navier Stokes equations, for comparison and validation. With regard to the latter, a sensitivity analysis on the simulation parameters was also reported in comparison to experimental results. Aim of this work was to improve the state-of-the-art with an extensive set of combined measurements and computations of different nature and objectives in order to provide a holistic view on the upwind sails aerodynamics.

Comparison of fatigue strength of post-weld improved high strength steel joints and notched base material specimens

ABSTRACTKeels of high-performance sailing yachts are highly stressed parts of the hull structure. Such keels are either milled or are welded hollow profiles. Recently a trend towards using high strength steel to manufacture keels is observed. While the fatigue strength of the parent material increases linearly with yield strength, it is independent of yield strength after welding. This problem can be overcome by post-weld improvement of the local weld geometry. Fatigue test results of the critical weld detail made from S900 steel are compared in welded state and after weld toe grinding. Additional tests of the same detail made from S355 steel, are performed. Moreover, tests of the notched parent material corresponding to a milled keel are presented. The fatigue strength of the grinded specimens was 2.2 times larger than in as-welded condition. The notched base material specimens act as an upper bound S-N curve for the post-weld improved specimens.

A Study on the Development of the Safe Navigation Route for a Sailing Yacht Focused on Geomundo (Port Hamilton)

This study suggests a navigation route for maritime tourism cruise sail yacht that sails off from Yeosu, and passes by Baekdo and Geomundo with their live island culture, to Kimnyeonghang of the Jeju islands. Recently, there are increasing number of accidents in proportion to vitalizing marine leisure. That`s why it should be examined by region and sea when developing safe sea route considering characteristics of the sailing yacht. Thus, it is needed to introduce marine culture, hold international sailing yacht race and develop multi-functional sea port according to the case of Geomundo. Also additional analysis for navigation ruote patterns and density of the fairway is required. This information will improve safe sailing level of sailing yacht that will help the local tourism industry.

세일요트의 모노킬과 트윈킬의 저항성능 비교

세일요트의 모노킬과 트윈킬의 저항성능 비교

Kite and classical rig sailing performance comparison on a one design keel boat

An implementation of a kite modelling approach into 6 degrees of freedom sailboat dynamic simulator is introduced. This enables an evaluation of kite performance in comparison with classical rig sailing.A zero-mass model was used to model kite forces. Influence of the wind gradient was properly taken into account leading to significant modifications in the calculation of the relative wind. The modelling was performed with experimental aerodynamic characteristics. An optimization was done to determine the best kite flight trajectory in terms of performance.Validation steps of the sail yacht simulator were performed for a classical rig on the example of an 8m one design yacht. The experimental set-up is described and validation results are discussed. Particularly, a wind mesh was used, based on measurements made at four different locations of the navigation spot. Additionally boat motions were recorded by high resolution GPS and inertial unit systems.Speed polar diagram results, reached by kite propulsion, were predicted versus true wind angle. At last a comparison was made for upwind and downwind legs in sea trials conditions, between simulations with the classical rig and the kite. It is shown that the boat towed by kite would achieve much better sailing performance.

세일요트 통합관리 시스템을 위한 웹기반 YWBS 설계 프로그램

Recently, the marine leisure industry has begun to make a mark on the growth engines of the Korean economy. Hence, various government research projects are in progress to catch up with the fundamental yacht technologies of advanced countries. Research on the integrated management technologies of sail yachts is carried out as a part of those projects. Work Breakdown Structure (WBS) is a basic architecture for robust and high-level management systems. In this paper, we suggest a product-oriented Yacht Work Breakdown Structure (YWBS). General WBS has a drawback in that it can only follow the targeted purpose, but YWBS allows for a generic WBS approach. This concept allows us to apply WBS to multi-purpose uses. The YWBS is used as an infrastructure in information management and for data relationships in sail yacht management systems. YWBS is designed and managed by a web application, and the system is implemented with a website as a user interface. This application has not only a design function, but also a data transfer function that is based on the Microsoft Silverlight platform, a kind of Rich Internet Application (RIA) technology. Using this application, YWBS designers can communicate with the management system without added tasks like as uploading and updating.

폴리에스터 고강력사를 이용한 요트용 세일의 제조 및 성능분석

This study surveyed the preparation of 8oz coated fabric and the physical property of the coated fabric according to the treated condition for the sail yacht. And the coated fabrics were compared with the performance of overseas products for verification. Physical properties of the coated fabric treated with non-yellowing functional polyurethane resin were examined according to the treatment condition such as compression and ageing treatments. Finally, yellowing fastness to light for 60 hours was assessed. Considering the compression condition after coating, good physical property was obtained at <TEX>$6kgf/cm^2$</TEX>. Also, the performance of yellowing fastness was similar to performance of overseas goods.

An experimental study of interceptors for drag reduction on high-performance sailing yachts

Interceptors have been widely used in recent years in fast ferries and small high-speed leisure and commercial craft for ride and trim control, and steering. In the context of high-performance sailing yachts, they first appeared in 2008 on the yacht Ecover 3 which was dismasted while leading the Vendee Globe Challenge race. However, in spite of their popularity in power craft, few studies have been published investigating the impact of interceptors on vessel performance, and apparently none in the case of sailing yachts. In the current study, interceptors are compared with an aerodynamic device known as a Gurney flap. It is shown that interceptors are generally substantially smaller than Gurney flaps. A comprehensive experiment programme is presented exploring the impact of interceptors on the performance of an Open 60 yacht hull. Results show a marked reduction in calm-water resistance over a wide speed range, with benefits of 10–18% in the speed range between 8 and 20 knots, accompanied by reduced sinkage and trim. The gains observed are much larger than those observed in powercraft, and also substantially greater than those achievable through trim changes by moving ballast longitudinally. The benefits appear to be largely sustained in small waves.

Modelling multiple yacht sailing interactions between upwind sailing yachts

An approach for enhancing the realism of yacht fleet race simulations based on a lifting line method is developed. The wake of an upwind sailing yacht is represented as a single heeled horseshoe vortex and image system. At each time step, changes in vortex strength are convected into the wake as a pair of vortex line elements. These subsequently move in accordance with the local wind, the self-induced velocity and the velocity induced by the presence of the wakes of other yachts. In addition, the lifting line model has a model for the viscous wake due to the drag associated with the yacht and its sails superimposed on it. A synthesis of sail yacht wake representations based on detailed 3D Reynolds-averaged Navier–Stokes computational fluid dynamics calculations with wind tunnel test results is used to capture the initial strength of the combined main-jib vortex system and its vertical height. The implementation of the lifting line algorithm within Robo-Race, a real-time yacht race strategy analysis tool, is described. Two upwind race interaction case studies are presented, and these show that the newly implemented wake model makes an important contribution to enhancing the realism of the sailing simulation.

Modelling of a Laser yacht mast

The purpose of this work to investigate the deflection of a Laser yacht mast caused by trimming forces (in plane deflection) occurring within the Laser yacht rig and create a model that reflects this. Finite element analysis software is used for the creation and analysis of the model based on structural mechanics principles. Verification of the model is carried out through comparison with experimental results, where deflection is determined in different wind conditions, and improvements of the model are based on the disparity of the model and the experimental results. References Anon, SolidWorks---COSMOSWORKS, Solidworks, Concord, MA, 2008, CAD FEA Software. P. Benham, R. Crawford, and C. Armstrong, Mechanics of Engineering, Pearson Education Ltd., England, 1996. D. Boote and M. Caponetto, Numerical Approach to the Design of Sailing Yacht Masts, The Tenth Chesapeake Sailing Yacht Symposium, ed Anon, Society of Naval Architects and Marine Engineers, Annapolis, 1991. H. Enlund, A. Pramila, and P. Johansson, Calculated and Measured Stress Resultants in the Mast And Rigging of a Baltic 39 Type Yacht, Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology 148 (1984) 41--49. G. Grabe, The Rig of the Research Sailing Yacht DYNA Measurements of Forces and fea, High Performance Yacht Design Conference 4--6, December, Auckland, 2002. G. Grabe, The Rig of the UCA---Finite Element Analysis, International HISW Symposium Yacht Design and Construction, Amsderdam Nov 15--16 2004. ISAF, IOC Confirms 10 Sailing Events For London 2012 Olympic Games, Centreboard Classes, International Sailing Federation, London, 2009. http://www.sailing.org/news/29214.php L. W. E. Media, Nautel Laser Masters World Championship, Margaret's Bay, 2009. http://can09.laserinternational.org/ D. D. Pearson, Tom Slingsby crowned 2008 Laser world champion, 2008. http://www.sailing.org/news/22202.php R. Shenoi, P. Conti, S. Turnock, and M. Scarponi, Mini 6.50 Mast Optimisation Using a Design of Experiment Approach and Finite Element Analysis Simulation, Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology (B1) 148 (2006) 41--49. R. L. Tillman, The Complete Book of Laser Sailing, McGraw-Hill, International Marine/Ragged Mountain Press, Thomaston, 2000.

30ft급 쌍동형 세일링 요트의 항주자세에 따른 실선저항 및 모멘트 추정에 대한 연구

During sailing by wind-driven thrust on the sail, a catamaran sailing yacht generates leeway and heeling. For estimating resistance and moment prediction of a real ship by changing of running attitude, a model test of the ship has to be carried out. This study aims at establishing experimental techniques for a catamaran sailing yacht by changed attitude during running direction. Through the model test, drag and side force of the real ship are predicted. Also through experiment, rolling and yawing moments were considered ※Keywords: Catamaran Sailing Yacht(쌍동형 세일링 요트), Model Test(모형시험), Resistance Prediction(저항추정), Running Attitude(항주자세), Hull Form Design(선형설계)

30피트급 요트의 유체력에 대한 실험적 연구

A model test was carried out, in order to verify the hydrodynamic performances of public 30 feet class sailing yacht. In the initial design stage, the performances and the running attitude of sail yacht including the hull form and sail plan, appendages were estimated by VPP, from which made the representative test conditions. A new experiment system such as captive model device was composed because the running attitude could be changed by wind conditions. The test results show that the minimum resistance is generated in the heeling 20 degree, which was expected in the initial design stage. It is thought to be the useful informations that the keel has au effects on hydrodynamic forces and resistance differences between the upwind and the downwind condition.