Average-lap racing (ALR) lets boats from a wide range of Portsmouth Numbers race together fairly by having them all sail for about the same length of time. Based on the number of laps each boat completes, its elapsed time is factored to represent the time it would have taken to sail the same number of laps as the fastest boat, then corrected in the normal way.
The corrected-time formula
Each boat's corrected time scales its elapsed time up to the leader's lap count:
Corrected Time = Elapsed Time × Most Laps × 1000 ÷ (Portsmouth Number × Actual Laps)
- Actual Laps: the number of laps the boat sailed.
- Most Laps: the number of laps sailed by the boat that sailed furthest.
When Actual Laps equals Most Laps this is just the ordinary Portsmouth Yardstick corrected time.
The Same PN adjustment
When boats with the same Portsmouth Number complete different numbers of laps, those sailing fewer laps can end up with lower (better) corrected times than they should. The Same PN adjustment increases the times of boats one lap down, applied only within that PN group:
Modified Time = Corrected Time × Multiplier
Multiplier = Slowest × (Fastest Laps − 1) ÷ (About-to-Finish Time × Fastest Laps)
- Fastest Laps: laps completed by the fastest boat in the group.
- Slowest: the elapsed time of the slowest boat in the group to complete Fastest Laps.
- About-to-Finish Time: the elapsed time at the about-to-finish (ATF) signal, given just before the leader crosses the finish line. In Sailboat Racing this is the first finisher's recorded time minus 5 seconds.
Example
Two Streakerss (PN 1124) race: Boat A completes 2 laps in 30 min 00 s, Boat B completes 1 lap in 14 min 00 s. Without the adjustment, Boat B would appear to win despite doing half the sailing.
| Boat | Laps | Elapsed | Corrected | Adjusted | Place |
|---|---|---|---|---|---|
| Streaker A (PN 1124) | 2 | 30:00 | 800.71 s | unchanged | 1st |
| Streaker B (PN 1124) | 1 | 14:00 | 747.33 s | 805.50 s | 2nd |
ATF = min(1800, 840) − 5 = 835 s. Multiplier = 1800 × 1 ÷ (835 × 2) = 1.078. Modified = 747.33 × 1.078 = 805.50 s.
A simpler method: same or slower rated boats cannot beat faster ones on more laps
Some clubs use a simpler rule: a boat with the same or higher Portsmouth Number (same or slower class) cannot rank ahead of a boat that completed more laps. There is no formula involved. The corrected times are kept as calculated; only the finishing order is adjusted when a violation is detected.
Importantly, a boat with a lower Portsmouth Number (faster class) on fewer laps is not affected by this rule and is ranked on its corrected time as normal.
Example: adjustment triggered
Streaker (PN 1124, 2 laps) and Solo (PN 1139, 1 lap). The Solo has a better corrected time but is slower-rated and completed fewer laps, so it is ranked behind the Streaker. Its corrected time is preserved unchanged.
| Class | PN | Laps | Elapsed | Corrected | Place |
|---|---|---|---|---|---|
| Streaker | 1124 | 2 | 30:00 | 800.71 s | 1st |
| Solo | 1139 | 1 | 14:00 | 737.49 s | 2nd |
Example: faster-rated boat on fewer laps, no adjustment
RS400 (PN 942, 1 lap) and Streaker (PN 1124, 2 laps). The RS400 is faster-rated (lower PN) so the rule does not apply between these two boats. Here the Streaker wins on corrected time, but if the RS400 had a better corrected time it would be ranked ahead without any penalty.
| Class | PN | Laps | Elapsed | Corrected | Place |
|---|---|---|---|---|---|
| Streaker | 1124 | 2 | 30:00 | 800.71 s | 1st |
| RS400 | 942 | 1 | 14:00 | 891.72 s | 2nd |
Source: RYA Portsmouth Yardstick Scheme, Average Lap Racing (Royal Yachting Association, 2007).