Following ORC Ireland's review of the results from Quintas Capital Calves Week 2026, ORC Ireland Rating Officer Pat Tanner says he went back through the individual race results to address what he describes as the “obvious issue” that the IRC and ORC fleets were not identical.
His subsequent like-for-like analysis concludes that 14 of 24 directly comparable boats — 58.3% — changed their overall finishing position between IRC and ORC, while two of the four class winners changed.
For context, Calves Week 2026 was the first Irish regatta to produce both IRC and ORC results for the same racing, allowing competitors to compare their performance under the two rating systems.
Tanner's analysis removes boats that were not competing under both systems and recalculates the IRC results race by race using only the common fleet.
Tanner Recalculates IRC Race by Race
Tanner says his analysis matched boats by name and sail number before retaining only those appearing under both rating systems.
Rather than simply deleting IRC-only boats from the final series table, he reconstructed the IRC standings race by race. IRC-only boats were removed from each individual race and the remaining boats re-ranked in their original IRC corrected-time order, with points reassigned. Penalties, retirements and non-starts were retained and the regatta's one discard after four races was then applied.
ORC-only boats were also removed from the other side of the comparison.
Tanner's analysis concludes that across the four spinnaker classes, 14 of the 24 directly comparable boats changed overall position between the recalculated IRC standings and ORC, while two of the four class winners changed.
He stresses that this does not establish that either system is better, but says it demonstrates that ORC was not simply reproducing the IRC results.
Class Zero Winner Changes
According to Tanner's recalculation, seven boats formed the common Class Zero fleet: Waterfront, El Syd, Rockabill VI, Joyride, I-Zimbra, Prima Forte and Out of Office.
Cris Tina was removed from the IRC side of the comparison and Prime Suspect from ORC.
The recalculated IRC standings put Waterfront first, El Syd second and Rockabill VI third. Under ORC, Rockabill VI was first, followed by Waterfront and El Syd.
The analysis therefore has the class winner changing and all three podium boats changing position between the two systems.
Different order – The Class Zero fleet at Calves Week. Pat Tanner's ORC Ireland analysis puts Waterfront first in the recalculated common-fleet IRC standings, while Rockabill VI takes first under ORC. Photo: Bob Bateman
J/109s Provide a Useful Comparison
Class 1 produced a substantially different outcome.
The five boats common to both systems — Artful Dodjer, Chimaera, Tighey Boy, Powder Monkey and Dear Prudence — were all J/109s.
Tanner describes this as a useful "control case" because of the closely related performance characteristics of five boats of the same design.
The two systems produced the same top three: Artful Dodjer first, Chimaera second and Tighey Boy third. Only Powder Monkey and Dear Prudence reversed fourth and fifth positions.
Tanner contrasts that result with Class 2, which contained a broader mixture of yacht types, sizes, generations and performance characteristics.
He does not claim that design diversity caused the different results, but says the comparison demonstrates that IRC and ORC can produce closely similar standings in a homogeneous fleet while producing materially different orders in a more varied fleet.
Seven of Nine Change in Class 2
Class 2 produced the greatest movement in Tanner's comparison.
Nine boats appeared under both systems and seven changed overall position.
Tanner's recalculated IRC standings have Miss Whiplash first, Ghost Raider second and Prince of Tides third.
The ORC order is Ghost Raider first, Black Velvet second and Miss Whiplash third.
IRC winner Swuzzlebubble does not form part of this comparison because the boat did not compete under ORC.
Tuco Wins Under Both Systems
Only three Class 3 boats appear in both relevant sets of results: Tuco, Excelsior and Manzanita.
Tanner's analysis has Tuco winning under both systems. Manzanita is second and Excelsior third under recalculated IRC, while the two reverse positions under ORC.
IRC winner Illegal and third-placed 3 Cheers were removed from the comparison because neither appeared in the ORC results.
Tanner excluded Whitesail from his overall 24-boat statistic because IRC divided the fleet into WS1 and WS2 while ORC used a different Whitesail grouping, meaning the class boundaries were not directly comparable.
What Does the Comparison Establish?
Tanner's report notes that IRC and ORC perform different handicap calculations.
IRC uses a single Time Correction Factor for each boat. ORC uses a Velocity Prediction Program to predict yacht performance across different wind strengths and sailing angles and, with the course-dependent scoring used at Calves Week, can take account of wind and course composition.
Importantly, Tanner says his analysis does not demonstrate that ORC is better than IRC, nor that IRC is wrong when the systems produce different finishing orders.
He says determining which system is fairest would require a broader study covering boat characteristics, wind strengths, course geometry and results across multiple regattas.
Instead, Tanner poses a narrower question: when exactly the same boats sail exactly the same races, does scoring them under ORC simply reproduce their IRC finishing order?
His Calves Week analysis concludes that it does not.
After the unmatched boats were removed and IRC was reconstructed race by race, Tanner's figures show 14 of 24 boats changing final position and two of four class champions changing, while the all-J/109 Class 1 fleet remained almost unchanged.
Read Pat Tanner's full Calves Week IRC v ORC Common-Fleet Analysis downloadable below as a PDF
