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With increasing interest in the ORC rating system across Ireland, particularly following its scheduled introduction to Dublin Bay in 2026, now is a timely moment to look closely at how ORC compares with the well-established IRC system, writes Mark Mansfield, the Cork-Harbour-based Professional Sailor, Sailmaker, and Rating Specialist.

As someone who has spent decades navigating, racing, and working within different rating frameworks, I’ve seen rating rules evolve—and sometimes cause confusion, controversy, and change. This article offers a personal perspective on how IRC and ORC work, their strengths and weaknesses, and what Irish yacht owners might expect if ORC becomes more widely adopted.

Formula X – Winner ORC Worlds 2025

There has been some controversy recently on the ORC rating of a new design—the X Yachts XR-41—which recently won her class at the ORC Worlds. Since then, the ORC organisers have decided she was too fast for her rating and have added a 10-second-per-mile penalty to her, as recently covered by Afloat.

The new XR 41 which has already made waves among racing enthusiasts, has been recently introduced to the UK and Ireland Photo: X Yachts

I have been around long enough to see many rating systems come and go: IOR, then IMS, then Channel Handicap; now we have IRC and ORC. In Ireland, we have been fairly well served by IRC for a number of years. Now ORC is the new kid on the block, and is trying to move in, claiming to be more advanced and a fairer system. But is it?

Background

IOR and IMS, both around in the 70s, 80s and 90s, were formula rating systems. That means all the data was up front and understood. Designers tried to get around the formula and come up with different hull shapes and other changes to beat the system. Sometimes they did, like when Ron Holland designed IMP in 1977. She was unbeatable. What did IOR do? They changed the rule a bit to take away most of the advantage. Eventually, IOR owners became unhappy with IOR as the boats it produced were not to their liking, and were expensive.

In the void, Channel Handicap came in, later becoming IRC. This had a secret formula and brought in a lot of cruiser-racers to be more competitive. Certain designs seemed to do a bit better on IRC, so tweaks every year happen—in secret—to again try to give a level playing field. IRC also endeavoured to keep the cost of getting a rating low, and in recent years penalised owners who were buying too many sails by limiting sail numbers allowed on their certs.

The Rolex Middle Sea Race from Malta Photo: Kurt Arrigo

IRC has been the major rating system worldwide, and is used on major classics such as the Fastnet Race, Sydney Hobart, Middle Sea Race, etc.

Then along came ORC, which morphed out of IMS. ORC is, like IOR in the past, a fully up-front rating system which uses modern technology to provide a VPP (Velocity Prediction Programme) system to determine how fast a yacht should go in all conditions. Designers know the formula and obviously try and beat the system by designing a yacht where the VPP system thinks a boat is slow, but in fact it is fast. That is, in effect, what seems to have happened with the XR-41 that has been causing issues recently. ORC are now trying to fix that boat’s VPP, but in the meantime have put a 10-second per mile penalty on the design. In IRC terms, this would be equal to about 70 seconds an hour or about 20 points of rating.

19 boats from a 40-boat fleet opted for an 'informal' ORC result in June's 2025 Dun Laoghaire Dingle Race, part of the 2025 ISORA season Photo: Afloat

For single point-to-point races, say an ISORA across from Dun Laoghaire to Wales in one condition, ORC would likely be a better handicap system as it can give a likely speed for each boat on that wind angle and wind strength and adjust the ratings to match. For example, a broad reach in 20 knots: a boat like a JPK 10.30 against a J/122. The JPK 10.30 will plane most of the way. The ORC VPP will understand that and a higher handicap will be used. The J/122 will not plane. So the JPK 10.30 may arrive first but will have a higher handicap than the J/122. So the J/122 could still win.

Pros and Cons – IRC

Pros:

• Simple
• Inexpensive to get a rating
• Adjusts secretly to keep a level playing field
• Used in major events
• Major rating system in Ireland, UK, Atlantic France, Holland, Australia, Hong Kong

Cons:

• Not easy to understand due to its secret formula
• May exclude certain designs and favour others (e.g., J Boats, JPKs, Quarter/Half Tonners appeared favoured under IRC)
• Uses one handicap number, so performance can vary by condition

The Royal St. George Yacht Club J122 Aurelia Photo: Afloat

Pros and Cons – ORC

Pros:

• More scientific, with a visible formula
• VPP helps match boat speed to rating
• Provides ratings for different wind angles and strengths
• Used widely in US, Northern and Mediterranean Europe

Cons:

• Generally more expensive (except simple club certs)
• VPP sometimes needs correction (e.g., XR-41 case)
• More complex to manage results
• Less transparent to sailors during racing
• Can favour certain design types just like IRC

Here in Ireland

There is a move to incorporate ORC as an additional rating system into Irish yacht racing. DBSC has agreed to this for 2026 alongside IRC and ECHO. Calves Week and Howth Yacht Club Autumn Series have also trialled ORC results. There’s a small but growing group advocating for it in major clubs.

So, should every boat owner give it their support? That is the question. For most, it will likely come down to: “Does this system favour my design under ORC?”

The Howth Yacht Club J/112e The Big Picture Photo: Afloat

IRC and ORC Comments

I asked both IRC and ORC to comment on this comparison article, and the following were their responses.

IRC responded that they are fully aware of the ORC introduction in Ireland and have been in contact with the ISA and other stakeholders to support and promote IRC within the Irish sailing community. They also noted that IRC certificates will be even cheaper in Ireland in 2026, with a substantial reduction.

They further highlighted that in many major jointly scored international events—such as the Aegean 600 and the Middle Sea Race—the results between IRC and ORC are often nearly identical in the top placings. This, they suggest, demonstrates the underlying fairness of both systems. Additionally, IRC raised a concern about the potential for increased costs under ORC due to optimisation needs, such as having to run different sail configurations, which may not be financially viable for many club-level owners.

ORC responded with a commitment to providing additional technical clarification around how their rating system is designed to work, particularly in relation to comparing IRC and ORC time correction factors (TCFs). They noted that many of the questions raised—including those around the XR-41—stem from misunderstandings of how ORC’s system is intended to be used. A full document is currently being prepared to explain the differences between IRC and ORC methodologies, and ORC, together with X-Yachts, plans to release a joint statement shortly. This will clarify the XR-41 situation and the reasoning behind the proposed 2026 solution.

ORC also advocated for the use of PCS scoring rather than APH. PCS, they argue, is a more effective method as it calculates windspeed based on the leading boat’s performance, eliminating the need to record actual windspeed during racing. While APH (tot) is not the method ORC will use in Ireland, it is what is closest to IRC’s single-number TCF and is what I’ve used here to provide a broad comparison.

Rating Comparison

The IRC Rating is simple—it is just one number. ORC has many ratings depending on course, wind strength and conditions.

To my understanding, if just one number is to be compared, the APH (tot) figure gives a rough indication and is the closest equivalent to IRC’s TCF. This is not the method ORC plans to use in Ireland, as they will be utilising more nuanced, condition-based ratings like PCS. So the comparison below should not be seen as definitive—just a broad indicator for context.

Clearly, based on this rough comparison, Rockabill would fare best on ORC, followed by Prima Forte, Aurelia, Valentina, and finally Big Picture.

This exercise could be extended to Classes 1, 2, and 3. It may show that some currently competitive IRC designs might not perform as well under ORC. That reflects the reality that many owners have chosen boats that align well with the IRC system.

The First 40 Prima Forte Photo: Afloat

Summary

Over the past 20 years, owners in Ireland have bought boats to race under the IRC system. Generally, the best-sailed boats perform well, but we’ve also seen that certain types—like J/109s and highly optimised Quarter and Half Tonners—do seem to have an edge under IRC.

The same will likely occur with ORC, with certain designs rising to the top. Our racing fleet is already under pressure from crew shortages, cost, and other factors, and many owners are shifting toward 'white sail' and Echo. It’s important that current boat owners feel reassured that their investments won’t be made obsolete by a new rating system. If they do, it could lead to further drop-offs in participation.

The phrase “don’t throw the baby out with the bathwater” comes to mind. Personally, if we were starting from scratch, ORC might be the better system—especially for boats that perform differently in different conditions. But IRC still does a pretty good job, and at this point, I don’t see any reason to fix what isn’t broken.