All ORC Rating systems use scientific methods and measurement technology to deliver its handicap systems. With a complete set of measurements of the hull with appendages, propeller, rig and sails and centre of gravity position, a Velocity Prediction software Program (VPP) is used to simulate the boat sailing in various wind conditions to generate a polar speed table. With this powerful tool, the ORC rating system can tell you the performance differences between different boats in different wind conditions around different course geometries.

This approach was begun for monohull yachts in the 1970’s. Since then, it has been under constant development through the work of the International technical Committee (ITC) which is a panel of scientists, sailors and designers who curate the research agenda which feeds into the VPP development.

Using the experience of more than 30 years of development of the ORC rating systems for the monohulls through the ORC International and ORC Club certificates, and in the last several years the widely used ORC Superyacht rating rule, ORC is now pleased to offer the ORC Multihull – rating system for any type of catamaran or trimaran.

The measurement procedures are similar to that for monohulls. The geometry of the hulls, superstructure and appendages are captured in the hull offset file, which can be based on physical scanning or verified designer CAD files. The Offset file format accommodates a variety of different appendage types such as curved foils or retractable boards. Rig measurements also follow the established monohull principles recognizing also multiple foretriangles that are typical for multihulls. Sail measurements follow the World Sailing Equipment Rules of Sailing (ERS). Additionally, propeller measurements are taken also following already established procedures and protocols. The detailed ORCmh Rules and VPP Documentation will be published in due course.

One of the main advantages of any ORC rating systems is flexibility of the scoring options. An ORCmh certificate provides a range of ratings, expressed as Time Allowances in s/NM for different wind conditions in the range of 6 – 20 knots of true wind speed for an optimum beat, and for 52, 60, 75, 90, 110, 120, 135, 150 degrees of true wind angle for an optimum run.
These time allowances are used in Performance Curve Scoring as a unique feature that is fundamentally different and much more precise than any other handicap system. It can rate different boats for different race conditions and course configurations by giving the boat’s theoretical predicted speeds for any wind condition and direction.

Time allowances for 7 wind speeds are also given for two pre-defined courses: Windward/Leeward is a conventional course where the racecourse consists of 50% upwind and 50% downwind legs, while the All Purpose course type includes equal distribution of all wind directions.

Additionally, simple scoring options with single number Time on Time or Time on Distance coefficients are given also for the Windward/Leeward and All-purpose course model. Using complete table of time allowances for different wind speeds and angles a custom singe number scoring may be calculated for each specific race using historical wind data or weather forecast prior to the race.

As Certificates are issued the ORCmh VPP will be subject to updates and improvements ahead of the ORC Congress meeting in the Autumn of 2021. For 2022 ORCmh will be adapted into the usual two Certificate process, as already exists for monohulls: ORCmh International that will be based on complete measurement, and ORCmh Club that uses the same data inputs which can be declared by the owner or obtained from another source such as photos, drawings, designs or data from identical or similar boats.

ORCi is intended for use on World, Continental, Regional and National level as well as major international offshore races, while ORC Club is as its name implies designed for Club-level racing that can go up to national championship level. Both systems having the same rating and scoring options and can be scored together in any races.

During this development phase ORCmh certificates will be issued by the ORC Central Rating office while from 2022 this will be extended to the National Rating Offices.

Any questions about ORCmh or requests for a test certificate may be sent by email to orcmh@orc.org

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