Scoring races to get acceptable race results is the primary function of race management. Competitors expect races to be run competently, and the results to reflect their abilities on the racecourse in a fair and unbiased way. With ORC’s use of scientific modelling of boat performance, this is possible with the correct selection of scoring type that best reflects the race type, the wind conditions and the expectations of the competitors.

One of three main characteristics of ORC rating systems besides science and transparency is the flexibility in scoring options. Since the ORC VPP produces a complete matrix of predicted boat speeds at various wind strengths and directions, ORC rating systems can therefore provide a wide variety of methods to calculate corrected time. This variety may look complex, but it is actually one of the strengths of the ORC rating systems to offer race managers choices that best suit their fleet, their race type and their race conditions. Choosing the best scoring option is therefore finding the right balance between accuracy and simplicity appropriate for the fleet.

The simple options shown on certificates include use of a single-number Time on Distance or Time on Time rating given for basic course types such as:
• Windward/Leeward course - has 50% upwind and 50% downwind race legs
• All Purpose course - includes equal distribution of all wind directions.

To improve accuracy and maximize the ORC rating system's potential, race managers can choose to utilize additional information and opt for Polar Curve Scoring (PCS) or tailor-made scoring options. Besides wind geometries, there are multiple other factors that should influence the selection of the scoring option.

Level of competition – For casual racing in club-level events with limited race committee resources, the simpler scoring options may be the appropriate choice. As the level of competition increases, then more sophisticated systems may be appropriate depending on the expectations of the sailors. For example, by default the windward/leeward races in ORC World and Continental Championships are scored using PCS with constructed courses – this is common for major National Championships and International regattas as well, and even for some local fleet competitions where this level of scoring is accepted and understood.

Class composition – Regardless of the scoring method selected it is important to have the fleet organized into racing groups (e.g. classes, divisions, sections, etc) of similar type. The scoring system works best when like-type and sized boats race each other, particularly when using the most accurate scoring options. Yet for long offshore races there may be a desire to list overall results that include all entered boats besides the results from separate classes.

Time on Distance vs Time on Time – Simple scoring options offer either Time on Distance or Time on Time ratings. The two are equivalent, and the choice can coincide with what the local fleet is accustomed to using. However, if the racing area has current, Time on Time is generally regarded as being more fair.

National Rating Office scoring options - National Rating Offices may publish on their certificates other scoring options. This may include ToD and/or ToT coefficients using different course models as well as multiple ToD and/or ToT coefficients for different wind ranges. The course type used to calculate these ratings and the methods of how they will be applied shall be specified in the Notice of Race and/or Sailing Instructions of the races and events that use them.

Polar Curve Scoring

Polar Curve Scoring is the most powerful engine of the ORC rating systems. It is this unique feature which makes this rule fundamentally different from any other handicap system, as it recognizes that yachts of varied design perform differently when conditions change.

This means that yachts of different designs will have different time allowances in each race depending on the weather conditions and the course configuration for that particular race. For example, heavy under-canvassed boats are slow in light airs but fast in strong winds, boats with deep keels go well to windward, and light boats with small keels will go fast downwind.

Where is it shown on the certificate?

An ORC certificate provides a range of ratings (time allowances expressed in secs/NM) for wind conditions in the range of 6 – 20 knots of true wind speed, and at angles varying from an optimum VMG beat to 52, 60, 75, 90, 110, 120, 135, 150 degrees of true wind angle, as well as the optimum VMG run angle. Additionally, two pre-selected course are available as:
Windward/Leeward (up and down) is a conventional course around windward and leeward marks where the race course consists of 50% upwind and 50% downwind legs. All Purpose includes equal distribution of all wind directions as a hypothetical course type in which the boat circumnavigates a circular island with the true wind direction held constant.

How is it calculated?

Taking for example, two boats with time allowances for All Purpose course their handicaps may be calculated as follows:

6 kt8 kt10 kt12 kt14 kt16 kt20 kt
Boat A964.1783.9679.9621.5588.0565.9541.2
Boat B881.3731.7679.9658.8644.4630.5610.7

This would mean that Boat B will give 82.8 seconds per NM to Boat A in light winds, while in strong winds it will be opposite with Boat A giving 69.5 seconds per NM to Boat B.

To score the race, race committee needs to select the wind strength to be used for the scoring. So called Soring Wind is calculated from the performance of the boats. Time allowances for 7 wind speeds may be presented as performance curve.

In a typical Performance Curve plot, the vertical axis represents the average speed of the boat around the race course, expressed in seconds per mile. The horizontal axis represents the wind speed in knots. When the finishing time of Yacht A is known, its elapsed time is divided by the distance of the course to determine the average speed in seconds per mile.

For example, if the elapsed time of the boat with the curve shown above is 1 hour 28 minutes 11 seconds and the total length of the course is 8.11 NM, the average s/NM for the boat on that course is:

Elapsed time: 1:28:11 hours = 5291 s
Course length: 8.11 NM
Allowance = Elapsed Time / Course length = 5291/8.11 = 652.4 s/NM

This value is then found on the vertical axis, and the software finds the point where it intersects the performance curve as shown below:

The corresponding point on this curve on the horizontal axis is the so-called Scoring Wind. This means the yacht has completed the course “as if” it has encountered that wind speed. The faster the boat has sailed, the higher the Scoring Wind, which is the primary index used for Polar Curve Scoring: the yacht with the highest Scoring Wind wins the race.

Scoring Wind is intended as an interpolation between time allowances, not an extrapolation. This means that when the Scoring Wind drops below 6 knots or raises above 20 knots, the time allowances used for calculating the corrected times will be those of 6 knots and 20 knots respectively. This does not mean that ORC races need to be stopped (or not started) with wind below 6 knots or above 20. When the Scoring Wind results calculate to be less than 6 knots or more than 20, the corrected time values at these wind speeds are then used.

With the winner known, the remaining rankings in the race are determined as follows: the Scoring Wind of the winner is used as the true wind speed to then calculate the corrected times of the other entries. With that wind on the horizontal axis, the appropriate time allowances are determined on each boat’s curve on the vertical axis. Such a time allowance is then used as a single number Time on Distance coefficient.

Constructed course

Further sophistication of the Polar Curve Scoring and use of full power of the ORC VPP may be achieved by defining the course when the course does not fit with one of the pre-defined course models i.e. any course different from Windward/Leeward course (50/50) or All Purpose with equal distribution of all wind directions.

The use of a constructed course is not as complicated as it may appear. It requires the Race Committee to provide only a little more data in addition to their usual work of setting up the course, following the wind changes, making starts and taking finishing times. ORC provides free PC-based ORC Scorer Software that will do all calculations that enable results to be ready as soon as the elapsed times of the race are entered.

The course may be constructed with these parameters in the ORC Scorer software:

  • distance
  • course bearing
  • wind direction

LegDistanceBearingWind direction
Start - 12.09 NM162160
1 - 1a0.06 NM060155
1a - Gate (2-2a)1.91 NM340155
Gate (2-2a) - 11.89 NM161160
1 - 1a0.06 NM0606160
1a - Gate (2-2a)1.91 NM340160
Gate (2-2a) - Finish0.19 NM316160

Typical course definition
. Distance and bearings of each leg are entered, as is the approximate wind direction. Note wind speed is not entered.Current velocity and direction can also be entered for each leg, if it is known.

From the course constructed as described above, the true wind angle (TWA) is calculated as being the difference between the wind direction and compass bearing of each leg. With this information, a table is made for each boat that describes the theoretical speed of that boat over that course for the range of seven true wind speeds (TWS). Calculated time allowances for these wind speeds are then used to calculate Scoring Wind and corrected times as explained above.

Time on Distance

Corrected time is calculated as follows:

Corrected time = Elapsed time – (ToDdelta * Distance)

Where ToDdelta = ToDthe boat   - ToDthe lowest (fastest boat) in the fleet

With Time-on-Distance (ToD) scoring, the coefficient of time allowance of one boat will not change with wind velocity, but will change with the length of the course. One boat will always give to another the same handicap in s/NM, and it is easy to calculate the difference in elapsed time between two boats needed to determine a winner in corrected time.

Where is it shown on the certificate?

Single number scoring options

How is it calculated?

ToD coefficients are calculated for the respective course model (Windward/Leeward or All-purpose) with the following wind strength distribution:

TWS6 kt8 kt10 kt
12 kt
14 kt
16 kt
20 kt
Time allowance%



A custom-made ToD coefficient may be calculated using a different wind distribution matrix based on wind historical data or weather forecast for a particular race. Course model to be used shall be specified in the Notice of Race and Sailing Instructions.

Handicap calculator

Boat A
Elapsed Time
Boat B

Time on Time

Corrected time is calculated as follows:

Corrected time = ToT * Elapsed time

With Time-On-Time (ToT) scoring, the time allowance will increase progressively through the duration of the race. Course distance has no effect on the results and need not be measured. Corrected time will depend only on the elapsed time, and the difference between boats may be seen in seconds depending of the duration of the races. The longer the race in time, the larger the handicap.

Where is it shown on the certificate?

Single number scoring options

How is it calculated?

ToT coefficients are calculated for the respective course model (Windward/Leeward or All-purpose) as follows:

ToT = 600 / ToD

A custom made ToT coefficient may be calculated using conversion factor to the custom made ToD coefficient. A conversion factor different from 600 may be set as ToD representing the middle of the fleet. Use of a different correction factor will not change the place in corrected times, it will only affect the differences in corrected time..

Handicap calculator

Boat A
Elapsed Time
Boat B

ORC Weather Routing Scoring

Weather Routing Scoring (WRS)

This new method for scoring medium and long-distance offshore races promises to combine the accuracy of modern weather forecasting with the power of the ORC VPP to produce fair handicap ratings for an entire fleet.

The concept relies on using PredictWind routing tools ( to determine for each boat its Predicted Elapsed Time (PET) for the race based on the weather and current conditions it experiences on the race course. 

The PET is used to determine a rating for the boat on that course, and the boat’s score for the race will be based on a comparison of the PET with the actual elapsed time.

The virtue of the method is that it uses the actual predicted weather conditions of the race rather than a generalized all-purpose or other pre-determined course model to determine ratings. 

Therefore, in theory, all boats have an equal chance to win because their ratings will reflect the weather they are predicted to encounter during the race. This is a significant step forward from assuming all boats in a race of any length encounter the same conditions.

A more detailed description of this approach can be viewed at

WRS will be used during the 2024 season in all ORC World and European Championship events with direct supervision by the ORC technical team, and be developed further during this season. 

Organizers of races of suitable length (eg, minimum overnight duration) for this method and who are interested in using WRS should include this language in their Notice of Race:
Offshore race results will be determined by corrected times calculated by the single ToT calculated by the Weather Routing as provided by the ORC. List of ratings will be published not later than (insert number) hours before the start.

And this in their Sailing Instructions:
The decision on the scoring method and scoring parameters used will be at the sole discretion of the race committee. The length of the course, compass headings of legs of the course, wind directions, and wind speeds will not be grounds for requests for redress by a boat. This changes RRS 60.1(b).

To apply for receiving WRS ratings from ORC, complete the form available at -  ORC Weather Routing Scoring request form for the event organizers

ORC Weather Routing Scoring Q & A