These notes are the compilers view of how the results are calculated. The notes are only to help club members (and the compiler) understand how the calculations are carried out and are certainly not meant to replace or alter the club sailing instructions which remain the definitive club sailing rule document.
The results are calculated in accordance with International Saling Rule guidelines and the rules of the Sugarloaf Sailing Committee. A set of Micorsoft Excel spreadsheets have been customised to meet the particular needs of the sailing program over one whole season so that the three series, Winter, Summer and Twilight are included. Also included are individual races such as the Marathon, Commodore's Cup, Parks Victoria Trophy and Club races. The published results on all web pages are provisional and subject to Sailing Committee endorsement at the end of the Season.
The calculation process requires several fundamental sets of data.
1. Boat and skipper information compiled from previous races including the yardstick for each of the classes of boat sailed during the season.
2. The current PHS number (Handicap) for each boat/skipper combination.
3. The registration (sign on/off) sheet information which includes the skipper and boat information relevant to the particular race.
4. The lap time data.
The sign on sheet is compared with the time data ensuring all boats are accounted for. Those that did not start or did not finish the course need to be marked accordingly.
The boat data base is updated to include any new boats.
The series database is up dated to include any boats that had not previously sailed in the relevant series.
The race information is then entered. This includes weather and course details and the starting time for each division.
Individual boat information is then keyed into the relevant race fields in the series database. If a boat has not sailed the course correctly, as indicated in the declaration area of the registration sheet, a code is entered in accordance with the following table.
The time sheet and video tape is a record of each boat's elapsed time for every South to North crossing of the sight line defined by the tower and the common mark. The video recording with its internal clock is run and compared against he timekeepers record. Any missing roundings or timing disparities on the timesheet are corrected and every sail number and time record is then entered into the the system. (Video tapes are archived for at least 10 weeks).
Having made all necessary entries, the system can then make the necessary time corrections (see 'Calculations' below).
Boats are ranked in order of increasing corrected time. This determines the position of each boat in the race. This applies to both boats with skippers who are club members as well as visiting boats. The system calculates cumulative points (see 'Points System' below) for the relevant race series. Up to 8 reports are generated for each race. Divisonal Yardstick and PHS Race Result, Divisonal Yardstick and PHS Progressive Aggregate Result and the same again for the Championship series.
These reports are then saved as HTML pages ready for uploading to the Web Server.
The system sorts through the elapsed time and sail number lists and then counts laps for each boat. Discrepencies are made obvious so that anomolies such as missing laps can be queried.
There are two types of calculations performed, 'Divisional' and 'Championship'.
Divisional calculations determine a result for boats within predetermined groups and 'Championship' results rank all boats.
Corrections are applied to both types of calculation in the following sequence:
All classes sail a common triangular course in terms of distance and angle. The number of laps, however, depends on yardstick and is set such that classes are sailing the course for approximately the same time and therefore during the same weather conditions.
For example, faster classes will sail five triangles. Slower classes may only sail two triangles.
The number of laps to be sailed for each class is available in the Sailing Instructions.
The start line is at or near the Club Common mark/gate. This Common mark/gate is common to all potential courses that may be set and is normally adjacent to the control tower where all roundings and finish line crossings are recorded as sail number and time. The common mark along with the tower alignment also describes the finish line. Lap splits are shown on each race result sheet.
The system identifies those common mark roundings that represent a complete triangle for each boat sailling each course. It finds the average lap time and multiplies this by the number of laps sailed by the fastest boat to create a time consistent with all boats sailing a common number of laps.
If there is not a complete triangle at the start as maybe expected in a race with a short start leg, this time is identified, adjusted proportionately and added to the above common lap, mean triangle time.
Shortened Course
The salient reason for shortening races is reducing wind strength.
At the time the decision is taken, boats are generally distributed around the triangle. With a range of classes sailing in up to 6 groups sailing a different number of laps, it is practically impossible to shorten the course for each group proportionately and certainly impossible to arrange the termination of the race so that boats sailing each course are on the water for exactly the same length of time. In varying wind strengths this time difference significantly effects the accuracy of the results.
To help overcome the problem, the system has a 'built-in', objective mechanism to either accept or reject final laps for each boat such that the elapsed time spread is minimised. The bulk of the fleet is assumed to be finishing its shortened race at around the time that 84% of laps have been recorded. This then provides an arbitrary point representing when the bulk of the fleet has finished and is compared with each boats penultimate and last lap to determine which should apply and which should be rejected.
Yardstick correction is to allow for the differences between boat performances based on class and some boat configuration changes within a class. This correction relies on the yardstick for each class.
Corrected Time = (100 X Elapsed Time)/Class Yardstick
Yachting Victoria yardsticks are generally used. One exception is the Yardstick for the Access 2.3 Servo class. Because of the limitations of a servo controlled boat, such as slower tacking and non servo actuated boom positioning on a run, 6 % is added to YV Access 2.3 (non servo) yardstick. This adjustment does not sufficiently cover the inability of an Access servo to reef while racing so a further adjustment of up to approx. 10%, is made depending on the strength and variablity of the wind.
PHS correction allows for both boat class differences and skipper performance. PHS correction is an alternative to Yardstick correction. Only one or the other is applied producing two different sets of results.
For the PHS correction, the back calculated yardstick derived from each skipper's individual performance is used - described below
Sugarloaf Sailing Club uses a non-linear algorithm. This function changes the PHS approximately proportionally where BCYS changes are small but limits changes to a maximum amount as sailors make large apparent deviations in BCYS relative to their previous PHS number. This ensures statistical outliers are suppressed.
Hc = Hcp(1 + 2 X 10/B X Artan(100 X ((1-1/B)+0.2)*(BCYS-Hcp)/Hcp)/(100 X pi))
Current PHS number = Hc
Previous PHS number = Hcp
A weighting coefficient that limits sensitivity to BCYS changes = B (set to 100/(the number of boats starting)). If the number of either cats or dinghies is less than 5 then only the number of boats sailing in each of these respective groups is used).
BCYS (Back Calculated Yardstick for the skipper's most recent race) = Yardstick X (Corrected Time)/(Corrected Time of 3rd Place).
Corrected Time = (100 X Elapsed Time)/Current PHS number
Corrections are applied to fleets comprising groups of boats that perform differently in varying conditions. The three groups are lightweight dinghies such as Sabre, NS14, Laser etc., multihulls such as off the beach catamarans like Taipan, Mosquitoand Hobie cat and displacemet craft like keel boats such as Access Dinghies and the Savage 16 Dolphin. There are alternative corrections applied at Sugurloaf.
This is the preferred hull type correction because it is based on a large body of data and is independent of the number of boats racing. It does not necessarily assume that the leading boats of each hull type are of a similar standard. It is applied where the race average wind speed is in the range 2 to 15 Knots.
For displacement craft such as access Dinghies and Savage 16, Dolphin, the correction is an approximation to compenstate for wave making resistance once the critical wave length has been reached, = Ys/(Ys+Wd2). Where Ys = the boats yardstick and Wd = Wind Speed-√(3.3.Lwl). Lwl is the water line length of the boat.
A correction based on catamaran versus dinghy performance data is applied to catamarans in preference to the Group Correction described below but only when the calculated wind strength is between 2 and 15 Knots. Catamaran performance relative to dinghies is so sensitive to wind speed below 2 knots that it is used only as a last resort when in is not possible to use the Goup Correction. There is currently insuffcient data for race average windspeeds over 15 Knots (Gusts to 30 Knots). The catamaran vs dinghy data is based on over 170 races where the first 3 Sabres have been compared with the fastest catamaran. Only the fastest catamaran is used because of the smaller cat fleet size.
This catamaran wind correction is derived from a 6th order polynomial curve of best fit to a scatter plot of calculated wind speed versus the ratio of the average of the first 3 Sabres times to the fastest Taipan 4.9 cat times multiplied by the ratio of the Taipan to Sabre YS. Over time, as more data is collected, the curve of best fit may change slightly in which case the polynomial coefficients are adjusted for subsequent calculations. This adjustment is initiated when the data has shifted the curve of best fit, shown below as a black curve 'Poly. (data)', more than 1% at any given wind speed from the current formula used in the calculations and represented as a red curve, 'formula'. The set of coefficients used for each race is shown on the results page.
The current wind correction curve and current coefficient set are shown below.
The above graph shows that the race data at Sugarloaf confirms that the relative YS for Sabres and Taipans is generally correct (shown as 1.0) over the whole wind range but that for winds less than about 7 knots, Taipans perform a few per cent more poorly and that for wind speeds above 7 Knots a few percent better unitl about 12 knots. Taipan and Sabre performance is taken as representative of 'off the beach' multihulls and lightwieght dinghies respectively.
Variation in hull performance is therefore compensated by this Wind Correction.
In those instances when wind speeds are less than 2 Knots and when a Group Correction cannot be applied (see below), a formula is applied cosnistent with the curve of best fit as follows:
Wind speed is determined by using the average time of the 2nd fastest Sabre in a formula which has been derived from over 100 races of calculated average race wind speed versus estimated average race wind speed. Wind Speed = (Sabre Speed1.72)/1.33
Group is an adjustment that relies for accuracy on a number of boats of each type competing and finishing a race. Importantly, it assumes that the leading boats in each group are genreally of an equal standard. The correction is found by subtracting the median of up to the 4 lowest corrected times from a group and the median of the 4 lowest corrected times for a second group. To avoid the variation associated with lower performing boats (as defined by their PHS), only boats that have a handicap less than 1.05 times Yardstick are used in the median calculation.
The Yardstick or PHS corrected time is corrected by adding this Group Correction. The object is to align (or standardise) the finish time distributions at the median of the fastest 4 boats (that meet the PHS criteria).
For those instances where less than two boats that meet the PHS performance criteria are racing, no median can be calculated and the system must revert to Wind Correction, regardless of wind speeds. See above.
For the purposes of determining position across a number of races that make up a series, points are allocated in accordance with the Low Point system.
For the purposes of adding points across a number of races, the points are divided into two types. Those that are allocated as a result of disqualification and those that are allocated for all other reasons. The DSQ points are fixed and remain part of the total points for the series.
All other points are subject to a rule that allows the points for a certain number of races to be dropped from each boat's tally depending on how many races are in a series. The following table shows the number of races that must be counted.
There is a minimum number of races in which boats must race to be included in this points system and thus be eligible for a series position. The minimum number of races equals 50% of the number of Series Races + 1 (rounded down).
The races dropped from the points tally are those that produced the highest points.
Boats will not appear in progressive result sheets until the minimum number of races have been sailed.
Average points representing a Skipper's performance, over those races in which he has completed without disqualification, are allocated to Skippers who are On Duty. The average is calculated from the total races sailed and includes points from races that may be subsequently dropped. The designation reported in the results is OD.
OD days are included in the tally for the minimum number of races in a series and for determining how many races can be dropped. Skippers have effectively sailed on OD days. OD points are not, however, eligible as dropped points.
Should a race be abandoned, the input to the system is zero whether the series entrant competed or not. Accordingly, categories such as DNC, DNF, DSQ do not apply and no time is entered. The race was effectively never scheduled nor sailed and unless it is resailed the number of races intended for the series will be reduced by one.
