Who sets Portsmouth Numbers?

The Royal Yachting Association (RYA) publishes the national Portsmouth Yardstick list each year, based on race returns submitted by clubs across the country.

Does a lower or higher Portsmouth Number mean a faster boat?

A lower Portsmouth Number means a faster boat. For example a fast skiff has a lower number than a slow training dinghy.

How the Portsmouth Yardstick works

Q: What is a Portsmouth Number?

A Portsmouth Number (PN) is a handicap value assigned to a dinghy class. A higher number means a slower boat. It is used to convert a boat's elapsed time into a corrected time so that boats of different speeds can be compared fairly.

The Portsmouth Yardstick (PY) is a handicap system that lets different classes of dinghy race together fairly. Each class has a Portsmouth Number (PN) (a higher number means a slower boat), and that number is used to convert each boat's elapsed time into a corrected time, so a fast skiff and a slow training dinghy can be scored in the same race.

What is a Portsmouth Number?

A Portsmouth Number is a measure of a class's typical speed around a course. It is deliberately relative, not absolute: the numbers only have meaning compared to each other. A boat with a PN of 1000 is, on average, faster than a boat with a PN of 1200. No measurement of the boat is required to receive a handicap, making the system straightforward for clubs to administer.

Where the numbers come from

The RYA maintains the national Portsmouth Yardstick scheme and publishes an updated list each year. The numbers are derived from real race results sent in by clubs across the country. Because they come from aggregated real-world racing, they reflect how boats actually perform across a wide range of conditions, not a theoretical calculation. See how PY returns work for details on how clubs contribute data.

The RYA also maintains a Limited Data List for classes that do not yet have enough returns to produce a fully statistically reliable number.

How a race is scored

In a handicap race, every boat sails the same course and its elapsed time is recorded. That elapsed time is then corrected using the class's PN. The boat with the lowest corrected time wins. The exact arithmetic, and a worked example you can try yourself, is on the corrected time calculator page.

A short history

The system was created by Stanley Milledge at Langstone Sailing Club in 1947. He used the Island One design as the baseline, assigning it a value of 100. The tables he produced were picked up by the Portsmouth Harbour Racing and Sailing Association in 1950, which supported their wider distribution to clubs.

In 1960, administration of the scheme transferred to the Royal Yachting Association, giving it a national footing. The system was extended to include multihulls in 1973. It has been refined continuously ever since and remains the most widely used dinghy handicap system in the UK.

Sailboat Racing scores Portsmouth Yardstick races automatically. Record finishes from your phone and corrected times are calculated for you. See how it works.

Last updated: 2026-06-03