Sailing and Racing Information pages

North American Portsmouth Yardstick

We at TLG use the Portsmouth handicap system for our races. US sailing assigns each boat a handicap number. The handicap number is based on actual sailing races. The lower the number the faster the boat. These numbers can be viewed on the US Sailing Web site.
The 2008 Portsmouth tables are at: www.ussailing.org

If a boat with a D-PN rating of 84 sails against a boat with a DPN rating of 94 and the race is for 100 minutes, the slower (D-PN of 94) boat would win if it came in less than 10 min. after the faster boat.

CT = ET x 100
            HC
CT = Corrected time
ET = Elapsed time
HC = D-PN or wind handicap number

for example, a PD Racer (a semi-open homebuilt class, and the slowest listed boat) has a US handicap of 140, and an A Scow (the fastest listed centerboard boat) has a US handicap of 61.8. 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 x 100 / 61.8 = 1.62 hours

PD Racer: 2 hours x 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.

The HC for a particular boat is adjusted depending on the wind strength. The wind strength is shown on the following Beaufort scale since some boats sail better in higher or lower wind.

Beaufort Scale of Wind Velocity

Beau-fort
No.

Knot

MPH

Seaman
Term

Sea Conditions

Typical
Wave
Height

0

0-1

0-1.7

Calm

Glassy-smooth, mirror-like  

Smooth

1

2-3

1.8-4.0

Light air

Scale-like ripples

Ripples

2

4-6

4.1-7.4

Light breeze

Small, short wavelets with glassy crests

1/3'

3

7-10

7.5-12.0

Gentle
breeze

Large wavelets, crests begin to break, occasional form

1-2'

4

11-16

12.1-18.9

Moderate breeze

Small waves, some whitecaps, more frequent form

2-3'

5

17-21

19.0-24.7

Fresh
breeze

Moderate longer waves, better formed, many whitecaps, much foam, some spray

3-4'

6

22-27

24.8-31.6

Strong
breeze

Large waves form, many whitecaps, foam everywhere, more spray

4-5'

7

28-33

31.7-38.5

 Moderate gale Sea heaps up, streaks of foam spindrift begins

5-6

8

34-40

38.6-46.6

 Fresh gale Moderately-high long waves, crests into spindrift, well-marked streaks of foam

6-7

9

41-47

46.7-53.9

 Strong gale High waves, sea rolls, dense streaks, spray affects visibility

7-9