Scoring IMS Regattas - An Empirical Study of Alternative Methods

1995 ◽  
Author(s):  
John W. Cane
Keyword(s):  
Empirical Study ◽  
Measurement System ◽  
Alternative Methods ◽  
Prediction Program ◽  
Data Points ◽  
Velocity Prediction ◽  
International Measurement

The International Measurement System (IMS) uses a computerized velocity prediction program (VPP) to calculate the performance of a meas­ured hull and rig in winds from six to twenty knots, at any sailing angle. A regatta is scored by comparing a yacht's performance with pre­dictions of the VPP. The winner is the yacht whose performance, relative to its VPP predic­tions, is the best, compared to all other yachts in its class or division. This paper discusses different methods of malc­ing the comparison and accounting for various factors in the race such as wind shifts and cur­rent on the course. Decisions made by race man­agers and/or developers of scoring programs can significantly impact results. Illustrative examples show the effects that these decisions can have. In 1994 the number of data points available for use in scoring yachts in custom courses doubled. Alternative ways of using these data are illus­trated by application to a sample regatta.

Changes to Sail Aerodynamics in the IMS Rule

2003 ◽  
Author(s):  
Jim Teeters ◽  
Robert Ranzenbach ◽  
Martyn Prince
Keyword(s):  
Wind Tunnel ◽  
Reverse Engineering ◽  
Measurement System ◽  
Wind Tunnel Test ◽  
Prediction Program ◽  
Aerodynamic Model ◽  
Velocity Prediction ◽  
International Measurement

US Sailing, the Offshore Racing Council (ORC), the Glenn L. Martin Wind Tunnel (GLMWT), Quantum Sail Design Group (QSDG), the Wolfson Unit and North Sails have collaborated on a series of wind tunnel test programs to investigate the performance of both upwind and offwind sails. These programs were initiated in response to perceived inequities in the ratings of boats of various rig designs sailing under the International Measurement System (IMS). Observations of on-the-water performance have lead to the conclusion that there are biases within the rule with respect to rig planform design. Specifically, it has been concluded that large spinnakers are penalized so that a fractional rig, with its small spinnaker, is favored when sailing offwind, that there are un-rated benefits to a masthead rig upwind, and that there are errors in the relative handicapping of overlapping and non-overlapping jibs. The IMS Rule uses a Velocity Prediction Program (VPP) in which sail forces are represented by algorithms that are based on a combination of science and reverse engineering from the measured sailing performance of real boats. The results of investigations at both GLMWT and Wolfson have been used to modify this IMS aerodynamic model, thereby reducing the pre-existing biases.

Aerodynamic Performance of Offwind Sails Attached to Sprits

2001 ◽  
Author(s):  
Robert Ranzenbach ◽  
Jim Teeters
Keyword(s):  
Aerodynamic Performance ◽  
Performance Potential ◽  
Prediction Program ◽  
Aerodynamic Modeling ◽  
Specific Goal ◽  
Velocity Prediction ◽  
Size Type ◽  
Improved Performance ◽  
Pole Configuration ◽  
International Measurement

The primary purpose of this offwind sail investigation was to better understand the relative performance of symmetric spinnakers flown from conventional poles and asymmetric spinnakers flown from conventional poles or sprits, i.e. poles restricted to the centerline. The specific goal was to improve the aerodynamic modeling of offwind sails used in the International Measurement System (IMS) handicapping formula to address perceived inequities in their performance potential, particularly when running at very deep angles. Running style offwind sails of varying size, type, and pole configuration were evaluated over appropriate ranges of angle of attack and trim settings. Improved performance coefficients were developed from this data for inclusion into the 2001 IMS velocity prediction program.

Analysis of Hull Shape Effects on Hydrodynamic Drag in Offshore Handicap Racing Rules

2003 ◽  
Author(s):  
Jim Teeters ◽  
Rob Pallard ◽  
Caroline Muselet
Keyword(s):  
Measurement System ◽  
Research Program ◽  
Hydrodynamic Drag ◽  
Joint Research ◽  
Fundamental Parameters ◽  
Calm Water ◽  
Shape Effects ◽  
Velocity Prediction ◽  
Joint Research Program ◽  
International Measurement

US Sailing and the Institute for Marine Dynamics (IMD) in St. John’s, Newfoundland, are collaborating in a joint research program to investigate the effects of hull shape variations on hydrodynamic drag. The results of this program are being used to support the development of rules that handicap racing yachts. A fleet of 9 models has been designed with systematic variations in the most fundamental parameters: displacement and beam for fixed length. Six of those models have been tested both appended and bare-hull, in calm water and head seas. Analysis of residuary resistance, both upright and heeled, has been used to improve the Velocity Prediction Programs (VPPs) employed by both the International Measurement System (IMS) and AMERICAP rules.

The Application of VPPs to Practical Sailing Problems

1987 ◽  
Author(s):  
Kart L. Kirkman
Keyword(s):  
Prediction Program ◽  
Widespread Acceptance ◽  
Velocity Prediction ◽  
Do So

The velocity prediction program, VPP, appeared on the yachting scene about ten years ago and it now dominates design and sailing. Originally implemented as a handicapping tool under the Measurement Handicap System, now accepted internationally as IMS, it has seen widespread acceptance for many other uses, from design to tuning and racing. This capability means that it is productive, even necessary, for the typical sailor interested in good performance to understand how to apply a VPP to his activities. To do so requires an appreciation of how a VPP functions and how it is applied to practical sailing problems, such as sail selection or tactics. The paper presents a review of VPP fundamentals and then treats the following applications: - Sail selection and strategy for offshore yachts. - Tuning and optimization of all boats. It is the goal of the paper to impart a working understand­ing of the VPP to many sailors so that they can take advantage of the technology in their normal activities.

Added Resistance in Seaways and its Impact on Yacht Performance

2007 ◽  
Author(s):  
Kai Graf ◽  
Marcus Pelz ◽  
Volker Bertram ◽  
H. Söding
Keyword(s):  
Strong Impact ◽  
Wave Spectra ◽  
Linear Extensions ◽  
Added Resistance ◽  
Optimum Length ◽  
Prediction Program ◽  
Strip Theory ◽  
Velocity Prediction ◽  
Added Resistance In Waves ◽  
Response Amplitude Operators

A method for the prediction of seakeeping behaviour of sailing yachts has been developed. It is based on linear strip theory with some non-linear extensions. The method is capable to take into account heeling and yawing yacht hulls, yacht appendages and sails. The yacht's response amplitude operators (RAO) and added resistance in waves can be predicted for harmonic waves as well as for natural wave spectra. The method is used to study added resistance in seaways for ACC-V5 yachts of varying beam. Results are used for further VPP investigations. The AVPP velocity prediction program is used to study optimum length to beam ratio of the yachts depending on wind velocity and upwind to downwind weighting. This investigation is carried out for flat water conditions as well as for two typical wave spectra. The results show that taking into account added resistance in seaways has a strong impact on predicted performance of the yacht.

scholarly journals How Korean Leadership Style Cultivates Employees’ Creativity and Voice in Hierarchical Organizations

SAGE Open ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 215824401987628 ◽  
Author(s):  
Hai Kyong Kim ◽  
Kibok Baik ◽  
Najung Kim
Keyword(s):  
Empirical Study ◽  
Leadership Style ◽  
High Energy ◽  
Positive Relationships ◽  
Voice Behavior ◽  
Paired Data ◽  
Indigenous Leadership ◽  
Korean Society ◽  
Fertile Ground ◽  
Data Points

This article examines how Korean leaders in a hierarchical society would trigger employees’ creativity and voice behavior through an indigenous leadership style: Korean leadership style (KLS). KLS exhibits heavily relationship-oriented behaviors, including attending to superiors’ needs and requests, building a positive reputation and trust of peers, and embracing and sheltering subordinates. Jeong, a shared group affect ingrained in Korean society, and woori, a shared feeling of belongingness dedifferentiating individuals constituting the collective, provide a fertile ground for this unique leadership style. Building upon the literature on group affect and collective energy, we explore how the affective mechanism mediates the positive relationships between KLS and employees’ creativity and voice behaviors. The findings from the empirical study of 340 leader–follower paired data points confirm the positive relationships between relationship-oriented Korean leader behaviors and employees’ creativity and voice behavior and that, for creativity, the link is partially mediated by positive affect with high energy.

scholarly journals Rowing VPP(Velocity Prediction Program)

2003 ◽  
Vol 2003 (194) ◽  
pp. 67-73
Author(s):  
Hiroshi Kobayashi ◽  
Takeshi Kinoshita
Keyword(s):  
Prediction Program ◽  
Velocity Prediction

scholarly journals High Froude Number Experimental Investigation of the 2 DOF Behavior of a Multihull Float in Head Waves

2021 ◽  
Vol 6 (01) ◽  
pp. 1-20
Author(s):  
Paul Kerdraon ◽  
Boris Horel ◽  
Patrick Bot ◽  
Adrien Letourneur ◽  
David David Le Touzé
Keyword(s):  
High Performance ◽  
Good Representation ◽  
Prediction Program ◽  
Modeling Approach ◽  
Head Waves ◽  
Wide Range ◽  
Dynamic Velocity ◽  
Velocity Prediction ◽  
High Froude Number ◽  
Stability Issues

Dynamic Velocity Prediction Programs are taking an increasingly prominent role in high performance yacht design, as they allow to deal with seakeeping abilities and stability issues. Their validation is however often neglected for lack of time and data. This paper presents an experimental campaign carried out in the towing tank of the Ecole Centrale de Nantes, France, to validate the hull modeling in use in a previously presented Dynamic Velocity Prediction Program. Even though with foils, hulls are less frequently immersed, a reliable hull modeling is necessary to properly simulate the critical transient phases such as touchdowns and takeoffs. The model is a multihull float with a waterline length of 2.5 m. Measurements were made in head waves in both captive and semi-captive conditions (free to heave and pitch), with the model towed at constant yaw and speed. To get as close as possible to real sailing conditions, experiments were made at both zero and non-zero leeway angles, sweeping a wide range of speed values, with Froude numbers up to 1.2. Both linear and nonlinear wave conditions were studied in order to test the limits of the modeling approach, with wave steepness reaching up to 7% in captive conditions and 3.5% in semi-captive ones. The paper presents the design and methodology of the experiments, as well as comparisons of measured loads and motions with simulations. Loads are shown to be consistent, with a good representation of the sustained non-linearities. Pitch and heave motions depict an encouraging correlation which confirms that the modeling approach is valid.

Relative Performance of Conventional Versus Movable-Ballast Racing Yachts

2005 ◽  
Author(s):  
Frank DeBord ◽  
Harry Dunning
Keyword(s):  
Physical Model ◽  
Morning Glory ◽  
Cfd Analysis ◽  
Design Issues ◽  
Design Features ◽  
Prediction Program ◽  
The Past ◽  
Trade Offs ◽  
Physical Model Tests ◽  
Velocity Prediction

Over the past few years several advanced concepts have gained wider acceptance from owners of large racing yachts and organizers of major international events. Two of these concepts, water ballast and canting keels, were evaluated during the design of the maxZ86 yachts Pyewacket and Morning Glory. This paper presents the key design features of these large movable ballast racing yachts and compares their performance to conventional racing yachts of similar size. Comparisons include results of physical model tests, CFD analysis using a panel code, velocity prediction program modeling, and sailing data from the existing boats. These results are accompanied by physical explanations of the differences, and the special testing and analysis requirements for the movable-ballast configurations are detailed. Finally, some of the design issues unique to the movable-ballast concepts and design trade-offs are discussed.

Upwind Sail Performance Prediction for a VPP including “Flying Shape” Analysis

2009 ◽  
Author(s):  
Brian Maskew ◽  
Frank DeBord
Keyword(s):  
Grid Point ◽  
Flow Simulation ◽  
Lattice Method ◽  
Prediction Program ◽  
Aerodynamic Pressure ◽  
Dynamic Velocity ◽  
Velocity Prediction ◽  
Coupled Structures ◽  
And Performance ◽  
Ultimate Objective

A coupled aerodynamic/structures approach is presented for predicting the flying shape and performance of yacht sails in upwind conditions. The method is incorporated in a flow simulation computer program, and is part of an ultimate objective for a simultaneous aeroelastic/hydro analysis in a Dynamic Velocity Prediction Program (DVPP), that will include a 6DOF motion solver, and at some point could include calculations in waves. The time-stepping aerodynamic module uses an advanced vortex lattice method for the sails and a panel method with special base separation treatment to represent the abovewater part of the hull and mast. A coupled inverse boundary layer analysis is applied on all surfaces including both sides of each sail membrane; this computes the skinfriction drag and the source displacement effects of the boundary layers and wakes, including bubble and leeside “trailing-edge” type separations. . At each step, the computed aerodynamic pressure and skin-friction loads are transferred to a coupled structures module that uses a network grid of tension “cords” in each sail membrane, each cord representing a collection of fiber “strings”. The solution of a structural equilibrium matrix provides the displacements needed to achieve balance between the aerodynamic and tension loads at each grid point as the shape iterations proceed. Details of the methodology used are presented and comparisons of predicted aerodynamic forces to wind tunnel results and an existing VPP sail model are provided. In addition, predictions are compared to some simple experiments to demonstrate the aerodynamic/structural coupling necessary to predict flying shape. Finally, an outline is given for incorporation of this methodology into the planned Dynamic Velocity Prediction Program.

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