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In January, 1976 the Offshore Committee of US Sailing adopted a
resolution calling for the development of a new "Handicapping
System" to take its place alongside the IOR for those yachtsmen
who "prefer a 'handicap' rule as opposed to a 'design' rule."
This system was developed in a response to the mandate of that
resolution, and was then called the Measurement Handicap System
or MHS. The name was intended to suggest that it is a formula
based on measurement of physical characteristics rather than
observed racing performance of yachts and that it is of the
handicap type as distinguished from the design or development
type.
The intent of the system as set down before starting the
development work may be summarised as follows:
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Weigh each factor used in the formulae to accord with its
effect on speed
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Reduce obsolescence
caused by the design of yachts which beat a rule and thereby
render older yachts not competitive
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Devise a system
which is designer-proof in the inception if possible, but by
correction as this proves necessary
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Provide fair time
allowance for yachts of the dual-purpose type (for cruising
and racing). It is intended that production yachts of good
design should be able to compete with custom yachts.
The system was based on the research at MIT of
the H. Irving Pratt Ocean Race Handicapping Project and started
with the development of a hull measuring device making it
possible to acquire a large number of points and so be able to
use integrated parameters instead of the single point
measurements.
The major part of this research was the
development of a Velocity Prediction Program (VPP) based on the
data obtained towing in the tank a series of hull forms
systematically modified to test the effects on speed of the
performance parameters. This important task was contributed by
Delft University in the Netherlands.
The measurement platform adopted was the same
as IOR, to enable an easy conversion into the new system of the
thousands of boats already measured under the International
Offshore Rule that was launched in 1970, and was the very reason
for the foundation of the ORC. In 1985 the MHS was converted
into an International System, renamed IMS and adopted by the ORC
for international use.
Work has continued on refining the speed
predictive formulae and on the best means of deriving time
allowance based on speed predictions, work largely made possible
by the contributions of designers and technologists in the
International Technical Committee (ITC) and yachtsmen from many
countries.
In January 2008, a new VPP running ORC
International and ORC Club rating systems was launched using the
measurement platform of the IMS, and the best elements of its
VPP, but has been revised to reflect more accurately the
performance characteristics of the most modern designs.
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