The Portsmouth Yardstick (PY) numbers list for 2025 has now been released with the first changes to the PY mathematic formula in 30 years.

Released annually at the RYA Dinghy and Watersports Show, the PY tool aims to level the playing field in the world of competitive sailing, making it easier for variety of different boats and classes to compete equally against one another.

Used around the world, Portsmouth Yardstick is a system, based on a boats relative performance set against the other boats they race with.  Fostering collaboration between clubs and working alongside the RYA, the easy-to-use approach enables clubs to run competitive  racing at all levels without requiring boat measurements

How does it work?

The RYA publishes a national list annually to provide a baseline for clubs to assign numbers to the boats racing within their fleets. Through PY Online, clubs can submit their race results to the RYA and use the tool to generate local numbers, reflecting how boats perform in their specific sailing conditions.

In order to score a PY race each boats elapsed time (time taken to sail around the race course) must be converted to a corrected time (time converted based on a boats PY number).

This is done by applying a simple correction calculation to each boats elapsed time. 

Evolving with the times…

The world of racing has changed over the years and 2025 marks a significant step in the PY  evolution. Working alongside Sheffield Hallam University to evaluate the tool against the current state of participation, this year marks the first change to how the system calculates PY since 1995.

The PY analysis tool applies basic criteria when assessing an individual race: it must have more than three finishers, feature more than one class, and have a race duration of over 20 minutes. From this data, the top 66% of finishers are used to calculate the average corrected time, with only those finishing within 105% of this time included in the PY calculations.

Following a review by Sheffield Hallam University, the RYA has widened this threshold to 110%, allowing the analysis of a broader range of race times. This adjustment enables the PY system to include more data without compromising on quality. Additionally, the tool has transitioned from using the mean to the median in its calculations, creating a more stable platform and reducing the impact of outliers.

The continuous development of the PY online website has also made data submission easier and more accurate, with the launch of the class list in 2024 further improving data accuracy.

“The Portsmouth Yardstick has been a cornerstone of dinghy racing for decades, and these latest updates mark an exciting update of the system. By modernising the calculation method for the first time in 30 years, we’re ensuring that the Portsmouth Yardstick system continues to reflect the changing dynamics of sailing. This is for our racing community and we encourage clubs to engage with PY Online, submit their race data, and take advantage of the improved accuracy and ease of use. Together, we can make racing even more competitive and rewarding for sailors of all levels,” said Adam Parry, RYA Technical Manager.

The RYA actively encourages clubs to submit race results via PY Online, allowing them to develop local numbers for closer competition. Created with the racing community in mind, without ongoing data submissions from clubs, the PY system cannot effectively operate and so its vital all those who use the system ensure they get involved.

When submitting data to the PY system, clubs are also encouraged to review the online lists and use the class configurations created. Any class that doesn’t appear on the list can contact technical@rya.org.uk

Find more information about the Portsmouth Yardstick System

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