Handicap systems: PHRF, ORC, IRC and Portsmouth.

Two ways to rate a boat

A handicap system gives each boat a number, and the race committee uses that number to turn elapsed time into corrected time. The systems fall into two families:

• Performance-based systems (PHRF, Portsmouth Yardstick) set the number from how boats have actually done on the race course. No measurement is needed.
• Measurement-based systems (ORC, IRC) calculate the number from a boat's physical measurements and data, not from its results.

PHRF

US Sailing describes the Performance Handicap Racing Fleet as an empirically based system designed to make ratings easier to get than measurement rules allow. It emerged in the early 1980s, loosely based on the 1940s West Coast "Arbitrary Fleet." Local handicappers or committees set ratings from observed performance, drawing on local conditions and experience, and US Sailing says any needed adjustment usually shows up after 5 to 10 races.

Certificates are issued by each local fleet, not nationally, which is why US Sailing tells sailors to check the Notice of Race for the fleet certificate an event requires. US Sailing publishes a PHRF Fleet Handicap Book of base handicaps from more than 60 North American fleets, covering more than 5,000 classes.

According to Wikipedia (a secondary source), a PHRF rating is expressed in seconds per mile relative to a theoretical boat rated zero, so a lower number means a faster boat. US Sailing's own page describes the scoring formulas rather than that definition. Races can be scored two ways:

• Time-on-distance, where the allowance depends on the course length.
• Time-on-time, where US Sailing gives the correction factor as A divided by (B plus the PHRF rating). It recommends 650 for A, and B varies with conditions: 480 for heavy air, 550 for average and 600 for light air.

Wikipedia adds that PHRF is mainly used for keelboats of about 7 m and longer in North America, while dinghy racing more often uses the Portsmouth Yardstick.

ORC

The Offshore Racing Congress began as the Offshore Rating Council, whose constitution was approved on 1 November 1969. It was renamed the Offshore Racing Council in 1976 and later became the Offshore Racing Congress. US Sailing says it was founded by the Royal Ocean Racing Club and the Cruising Club of America, that World Sailing recognizes the ORC Rule as an International Rating System, and calls it the most popular measurement-based rating system in the world.

ORC's earlier rules trace the history of rating: the International Offshore Rule (IOR) was recommended in 1968 for the 1969 season, and was largely replaced by the International Measurement System (IMS), which ORC adopted in 1985. ORC Club arrived in 1998 as a simpler, lower-cost option, and ORC International launched in 2007.

ORC ratings come from a Velocity Prediction Program (VPP) that uses measurement data to predict a boat's speed across a range of wind speeds and angles. US Sailing says the VPP is updated every year and its rules and documentation are public.

• ORC International certificates require full measurement.
• ORC Club certificates allow some data to be declared or estimated. The rating office fills in unmeasured values with defaults that give a slower rating. Both types can race together.
• Other types include Double Handed, Non-Spinnaker, One Design, Super Yacht and Multihull certificates. One Design certificates cover standard class configurations and need no measurement if the boat complies with its class rules.

Scoring options are time-on-distance, time-on-time and Performance Curve Scoring, which applies different handicaps for different wind strengths and angles. ORC also publishes a General Purpose Handicap (GPH), an average of time allowances used for quick comparisons and for splitting boats into classes.

IRC

IRC is owned by the Royal Ocean Racing Club (RORC) and the Union Nationale pour la Course au Large (UNCL). Its Rating Authority is made up of the RORC Rating Office and UNCL's computing center at the Yacht Club de France. IRC says it and its predecessor, CHS, have been rating boats for more than four decades.

An IRC rating is a single number, the Time Corrector Coefficient (TCC), calculated from a boat's measurements and data rather than from race results. Corrected time is elapsed time multiplied by TCC. US Sailing says TCC values run from 0.750 to 2.000, with most cruiser-racers between 0.900 and 1.100. The calculation itself is not published, and a rating can only change if the input data changes.

IRC is self-measured. An "endorsed" certificate has had its weight and measurements verified, and some events require one. Events that use IRC include Cowes Week, the RORC Caribbean 600, the Rolex Middle Sea Race, the Rolex Sydney Hobart and the Rolex Fastnet Race.

Portsmouth Yardstick

The Portsmouth Yardstick rates boats on how they perform against the boats they race with. Clubs allocate and run the handicaps, and no measurement is needed, which lets mixed fleets of dinghies, keelboats and multihulls race together. The RYA publishes several lists each year (the Current PY list, a Base list and a Limited Data List), and clubs may set local numbers to suit their own waters.

According to Wikipedia (secondary):

• Corrected time equals elapsed time multiplied by a scale factor, divided by the Portsmouth Number. The scale is 1000 for UK numbers and 100 for US and Australian numbers.
• Stanley Milledge created the system in 1947 at Langstone Sailing Club near Portsmouth and handed it to the RYA in 1960.
• The US version is the Dixie-Portsmouth Number (D-PN), which NAYRU (now US Sailing) took over in 1973.

One-design: no handicap at all

In one-design racing the boats are identical or nearly so, so no handicap is needed and the first boat to finish wins (Wikipedia). Wikipedia credits Thomas Middleton of the Shankill Corinthian Club near Dublin with proposing the idea in 1887 with the Water Wag dinghy, and names the Laser, Melges 24, Dragon, J/24 and Etchells among well-known classes. At the top level, SailGP races identical F50 catamarans and the America's Cup preliminary regattas use the one-design AC40.

Many regattas mix the two. The 2025 Rolex Big Boat Series in San Francisco ran one-design classes (Express 37, J/105 and J/88) alongside ORC handicap divisions. See one-design and Olympic classes for the boats themselves.