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Rating systems are always an important topic
among sailors. Those that regularly lose races use the rating
system as their main excuse, while winners will believe that
same rating system is the best in the world. Characteristics
that are positive for boat speed, like length of the water line
or sail area, and those that are negative, like beam,
displacement and wetted surface, are the most common influences
in any rating system. Establishing which of these
characteristics influences boat speed is therefore the problem
that has to be resolved by all known rating systems. Thanks to
the developments in modern science and technology, ORC
International gives the most accurate solution to this problem,
and establishes important principles of boat measurement and
calculation of corrected times.
ORC International system does not compare boats, like any other
traditional rating system, but the capability of the race crew.
This rating rule uses mathematical models and large number of
measurements, including hull lines, to calculate the theoretical
time that a boat should complete a given race course in the
given conditions. The boat that achieves the best corrected time
is the one that completes the course in the shortest possible
time relative to this theoretical limit.
Another way to
look at this is that sailors are supposed to do their best in
racing their boat and not being concerned with the corrected
times of other boats. The race is against the clock, and not
necessarily against their opponents, as any deviation from
sailing the fastest track around the course will result in a
lower corrected time performance. And finding holes in the rules
to “adjust” the boat’s rating does not help much either, as this
puts extra demands on crew performance.
No rating system
before ORC International has taken into account the varied
performance characteristics found between boats. ORC
International ratings are a total of ratings for various
conditions: wind strength of 6, 8, 10, 12, 14, 16 and 20 knots,
direction of true wind from the close-hauled to 52, 60, 75, 90,
110, 120, 135, 150 and 180 degrees. With this data it is
possible to establish a polar diagram that shows the speed of
the boat in relation to wind strength and its direction. This
enables sailors to compare the speed of their boat to
theoretical speeds from their rating certificate. It also gives
them the possibility to learn the trim of their boat in order to
achieve the best possible speed in any particular conditions.
The computer
program that produces polar diagrams consists of two parts: LPP
(Lines processing program) and VPP (Velocity prediction
program). LPP calculates hydrostatic data, like wetted surface,
displacement and stability. These are necessary inputs for the
VPP program which creates a computer simulation of the boat’s
performance based on scientific research of boat hulls in
hydrodynamic basins, sails in aerodynamic tunnels and
measurements taken on real boats. Hull resistance is calculated
in sailing trim with the total crew weight and equipment onboard
for various angles of inclination and wind strength. Forces that
propel and heel the boat are calculated for all possible
combinations of sails, along with a choice of the optimal
combination for the given conditions.
ORC International
certificates have quite a large amount of data that allows for
several ways to calculate corrected times, including simple
scoring options with just one, two or three scoring
coefficients. What makes ORC International unique from other
rating systems is that it allows for different ratings in a race
depending on weather conditions and the course type, thereby
producing more accurate ratings. Thus a heavy boat with smaller
sail area will be rated as slow in light winds, but will be
faster in stronger winds; boats with deep keels will be rated
fast upwind, just as light boats with smaller keels will be
rated fast downwind.
To use all the features of ORC International a
personal computer is essential. It is possible to score an ORC
International regatta without one, but then all its capabilities
cannot be used. ORC International is at its best in “round the
buoys” racing where the course is defined with three items:
compass bearing, length of the leg and wind direction on each
leg of the course. The course definition is taking in account
how many beats, reaches or runs a boat was sailing and the wind
speed used for calculating corrected times based on boat's
theoretical performance in such conditions. And unlike any other
rating system, ORC International also offers different
scoring methods, giving the option to the race organizers to
choose the best one for their local conditions, including size
of boats, type or course or wind conditions.
ORC rating systems, like any other, is not
perfect, but it does use the latest in science and technology to
promote fair competition between boats of different
characteristics, which gives sailors a chance to demonstrate
their abilities. The number and quality of the ORC International
and IMS boats at recent World and European championships proves
this, and this is why the
International Sailing Federation (ISAF) recognizes only ORC
International as the rating system to be used for offshore World
Championships. |