Portsmouth yardstick
Encyclopedia
The Portsmouth Yardstick (PY) or Portsmouth handicap scheme is a system of handicapping
used primarily in small-boat yacht racing
.
The handicap is applied to the time taken to sail any course, and the corrected time can be used to compare widely different sailboats on even terms. Portsmouth Numbers are continually updated with empirical
data from race results worldwide. Numbers are provided for differing wind speeds (when the data are available), plus a composite number that can be used when the wind speed is variable or unknown.
The Portsmouth numbers are administered in the United States
by the Portsmouth Numbers Committee, and in the United Kingdom
by the Royal Yachting Association
, based on annual input from a large number of affiliated sailing clubs. While the two systems are similar, the US version (D-PN) uses handicap numbers scaled to 100, while the RYA version changed to a scaling of 1000 in the 1990s.
Each class of boat is assigned a "Portsmouth Number", with fast boats having low numbers and slow ones high numbers—so, for example, in the case of two dinghies
, a 49er
might have a RYA-PY of 740 while a Mirror has a RYA-PY of 1385 (these are the actual RYA Portsmouth numbers for 2011, but note that adjustments are made each year).
In a race involving a mixed fleet, finishing times can be adjusted using the formula:
where Scale is 100 for US numbers, and 1000 for UK numbers, and Handicap is the applicable Portsmouth Number for the given class of boat. Each boat's time is adjusted with the formula, and then the adjusted scores are compared to determine the outcome of the race.
For example, a PD Racer
(a semi-open homebuilt class, and the slowest listed boat) has a D-PN of 140, and an A-Scow
(the fastest listed centreboard boat) has a D-PN of 61.3. If an A Scow takes 1 hour to finish a given course, and a PD Racer takes 2 hours, the handicapped times are:
So the PD racer, although it took twice as long to finish the course, would be declared the winner. Numbers in the UK handicapping system would yield similar results, though some slight variation is to be expected due to variations in the race data used to compile each handicapping chart.
and small keelboats or multihulls. Larger sailboats are more likely to use the Performance Handicap Racing Fleet handicapping system in North America, or the IRC
handicapping system in Europe, Australia & New Zealand.
There is a linear correlation between the D-PN and PHRF, allowing the following conversions formulas:
Handicapping
Handicapping, in sport and games, is the practice of assigning advantage through scoring compensation or other advantage given to different contestants to equalize the chances of winning. The word also applies to the various methods by which the advantage is calculated...
used primarily in small-boat yacht racing
Yacht racing
Yacht racing is the sport of competitive yachting.While sailing groups organize the most active and popular competitive yachting, other boating events are also held world-wide: speed motorboat racing; competitive canoeing, kayaking, and rowing; model yachting; and navigational contests Yacht racing...
.
The handicap is applied to the time taken to sail any course, and the corrected time can be used to compare widely different sailboats on even terms. Portsmouth Numbers are continually updated with empirical
Empirical
The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....
data from race results worldwide. Numbers are provided for differing wind speeds (when the data are available), plus a composite number that can be used when the wind speed is variable or unknown.
The Portsmouth numbers are administered in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
by the Portsmouth Numbers Committee, and in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
by the Royal Yachting Association
Royal Yachting Association
The Royal Yachting Association is the national governing body for certain watersports in the United Kingdom. Activities it covers include:* Sailing* Windsurfing* Motor cruising* Sportsboats* Personal watercraft* Powerboat racing...
, based on annual input from a large number of affiliated sailing clubs. While the two systems are similar, the US version (D-PN) uses handicap numbers scaled to 100, while the RYA version changed to a scaling of 1000 in the 1990s.
Each class of boat is assigned a "Portsmouth Number", with fast boats having low numbers and slow ones high numbers—so, for example, in the case of two dinghies
Dinghy
A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...
, a 49er
49er (dinghy)
The 49er is a double handed twin trapeze skiff type sailing dinghy. The two crew work on different roles with the helm making many tactical decisions, as well as steering, and the crew doing most of the sail control. The design, by Julian Bethwaite, the son of Frank Bethwaite , is revolutionary...
might have a RYA-PY of 740 while a Mirror has a RYA-PY of 1385 (these are the actual RYA Portsmouth numbers for 2011, but note that adjustments are made each year).
In a race involving a mixed fleet, finishing times can be adjusted using the formula:
- Corrected Time = Elapsed Time × Scale / Handicap
where Scale is 100 for US numbers, and 1000 for UK numbers, and Handicap is the applicable Portsmouth Number for the given class of boat. Each boat's time is adjusted with the formula, and then the adjusted scores are compared to determine the outcome of the race.
For example, a PD Racer
Puddle Duck Racer
A Puddle Duck Racer or PD Racer is an 8 foot long, 4 foot wide, 16 inch high, spec series, racing sailboat or day sailer. It is a one design hull shape with wide options in other areas. Billed as "the easiest sailboat in the world to build", the scow hull is a simple box, usually built of...
(a semi-open homebuilt class, and the slowest listed boat) has a D-PN of 140, and an A-Scow
A-Scow
In sailing, the A-Scow is a large sailing scow. It is 38 feet long and with reported top speeds of over 25 knots. With its rules of design, also known as scantlings, first beaten by its father in 1901, the A-Scow has a significant history...
(the fastest listed centreboard boat) has a D-PN of 61.3. If an A Scow takes 1 hour to finish a given course, and a PD Racer takes 2 hours, the handicapped times are:
- A Scow: 1 hour × 100 / 61.3 = 1.63 hours
- PD Racer: 2 hours × 100 / 140 = 1.43 hours
So the PD racer, although it took twice as long to finish the course, would be declared the winner. Numbers in the UK handicapping system would yield similar results, though some slight variation is to be expected due to variations in the race data used to compile each handicapping chart.
Boats And Their Portsmouth Numbers
- Dart 16Dart 16The Dart 16 is a one-design 4.80 m long sailing catamaran. It is designed to be sailed by two people.-Design:The Dart 16 is a modern beach catamaran that is fast, affordable, and seaworthy.The boat lacks the dangerous main boom,...
(With Asymetric spinnakerSpinnakerA spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
- 853 - Dart 18Dart 18The Dart 18 is a one-design long glassfibre sailing catamaran. It is designed to be sailed by two people and can achieve speeds of up to 20 knots.-History:...
- 798 - Laser 2000 - 1090
- Laser 3000Laser 3000The Laser 3000 is a racing sailing dinghy crewed by two persons with a trapeze for the crew. Launched in 1996, the 3000 was developed from the Laser 2, using the original Frank Bethwaite-designed planing hull combined with a brand new self-draining deck by Derek Clark...
- 1032 - Laser 4.7Laser 4.7The Laser 4.7 is a one-design dinghy class in the Laser series and is a one-design class of sailboat. All Lasers are built to the same specifications. The Laser is 4.06 m long, with a waterline length of 3.81 m . The hull weight is 59 kg...
- 1175 - Laser 4000Laser 4000The Laser 4000 is a well known racing dinghy crewed by two persons. Its one-design weight-equalised system enables physically differing sailors to compete on a level playing field. It is most popular in Europe, particularly the UK, France and Italy.The 4000 is a fast, planing skiff-style dinghy...
- 908 - Laser Pico (Single Handed) - 1260
- Laser Stratos (Centre Board) - 1087
- OptimistOptimist (dinghy)The Optimist is a small, single-handed sailing dinghy intended for use by children up to the age of 15. Nowadays boats are usually made of fiber reinforced plastic, although wooden boats are still built....
- 1646 - Penguin (dinghy)Penguin (dinghy)The Penguin is an cat-rigged sailing dinghy designed in 1938 by Philip Rhodes. The design experienced a surge in popularity after an article with construction plans was published in Yachting Magazine in 1940. The boat was originally designed to be easily built by an amateur at home out of plywood...
- 111.5 - RS FevaRS FevaThe RS Feva is a two person sailing dinghy designed by Paul Handley in 2002. It is manufactured and distributed by RS Sailing. The RS Feva is an International Sailing Federation International Class, a Royal Yachting Association Supported Junior Class, and has been selected by the Dansk Sejlunion...
- 1189 - WayfarerWayfarerWayfarer may refer to:*Wayfarer , an alternate shell for Windows 3.1x*Wayfarer , a class of sailboat*Wayfarers *Ray-Ban Wayfarer, a brand of sunglasses*The Wayfarer, a 1510 painting by Hieronymus Bosch...
- 1101 - BuzzBuzz-People:*Buzz Aldrin , American pilot and astronaut, second person to set foot on the Moon*George Beurling , Canadian World War II fighter pilot*Buzz Hargrove , National President of the Canadian Auto Workers trade union...
- 1006 - ISO - 926
- 29er29erThe 29er is a two-man high performance skiff designed by Julian Bethwaite and first produced in 1998.-Background:It is targeted at youth, especially those training to sail the larger 49er. It has a single trapeze and a fractional asymmetric spinnaker. The Class is a more modern replacement to...
- 924 - FinnFinnFinn is commonly used to refer to a member of the Finn ethnic group or a citizen of Finland.a name* Finn , a Frisian King, who appears in Beowulf and The Fight at Finnsburg...
- 1069 - OptimistOptimistAn optimist is a person with a positive outlook on life.Optimist may also refer to:* A member of Optimist International* The Optimist, a small sailing dinghy sailed by children...
- 1646
Other handicap systems
The Portsmouth Yardstick is used for dinghy racingDinghy racing
Dinghy racing is the competitive sport of sailing dinghies. Dinghy racing has affected aspects of the modern dinghy, including hull design, sail materials and sailplan, and techniques such as planing and trapezing.-Organisation of dinghy racing:...
and small keelboats or multihulls. Larger sailboats are more likely to use the Performance Handicap Racing Fleet handicapping system in North America, or the IRC
IRC (Sailing)
IRC is a system of handicapping sailboats and yachts for the purpose of racing. It is managed by the Royal Ocean Racing Club in the United Kingdom through their dedicated Rating Office....
handicapping system in Europe, Australia & New Zealand.
There is a linear correlation between the D-PN and PHRF, allowing the following conversions formulas:
- D-PN = ( PHRF / 6 ) + 55
- PHRF = ( D-PN − 55 ) × 6
External links
- Portsmouth Yardstick at USsailing.org
- Portsmouth Yardstick at RYA.org.uk
- Portsmouth Number List 2011 at RYA.org.uk