USE of PORTSMOUTH NUMBERS(D-PN) or WIND DEPENDENT HANDICAPS(Beaufort Range)

(WEBMASTER NOTE: This page is built on Guidelines issued by the USYRU Portsmouth Yardstick System.  Examples are based on National One-Design racing, and intended to make “mixed” fleet racing easier for NODRA and NOD boat owners.)

DECISIONS BEFORE RACING BEGINS

A.  Handicapping:

1)  Decide on handicapping method/systems to be used.

a) D—PN “only” for handicapping.

b) Wind Velocity Handicaps(Beaufort Range)”only” (determining the average wind velocity required).

c) D—PN or Wind Velocity Handicaps modified for allowances.

2)  Determine handicaps for all non-listed classes before racing begins.

3)  Grouping boats into fleets by handicaps is optional.

B.  Scoring:

Decide on method for scoring.

C.  Time Limit:

Consider time limits. Changing weather conditions during a race will upset the handicapping system. A one hour race for the bulk of the fleet is recommended.

D.  Course:

Triangular courses of equal beating, reaching, and running legs are recommended for handicap races.

RACING

A.  Record start and finish times for each boat in the handicap fleet(s) and for first boat to finish in one—design or level racing fleet(s).

B.  Record wind velocities at the start, middle and finish of each race.

C.  Determine average wind velocity (this is the sole responsibility of the Race Committee, whose decision is final).

CALCULATION

A.  Determine elapsed times(ET) for each boat of the handicap fleet(s) and for first boat to finish in one—design or level racing fleet(s).

B.  Determine average wind velocity for each race. Determine Beaufort Number range and appropriate handicap “if” wind velocity handicaps are being used.

C.  Calculate the Corrected Times(CT) from Elapsed Times (ET) and handicaps (HC) using the formula:

ET (using decimals for seconds)

CT = ---- x 100

HC

D.  Score race and determine places based on shortest corrected time (CT).

EXAMPLE

1) A National One-Design(D-PN 96.3), a Thistle(D-PN 83.0), and a Laser(D-PN 91.3) have decided to race using the D-PN handicap method.  The race committee is new and does not believe it can apply the “HC Beaufort Range” properly.  All 3 boats start at 1:00:00 PM and sail “once and a leg” on a triangular course set to winward.  The Laser crosses the finish line at 1:45:56, the National One-Design(NOD) finishes at 1:46:01, and the Thistle finishes at 1:48:00.  Which boat has “won” the race ?

2) Let’s determine the Elapsed Times (ET)

BOAT                 Times HH:MM:SS       ET      ET in DECIMALS

-------------------  -----------------   -------   ---------------

National One Design  1:46:01 – 1:00:00 = 00:46:01 = 46.02

Laser  1:45:56 – 1:00:00 = 00:45:56 = 45.93

Thistle  1:48:00 – 1:00:00 = 00:48:00 = 48.00

3) Next, determine the Corrected Times (CT)

Portsmouth Formula   CT

-------------------   ------------

National One Design:  (46.02/96.3)*100  = 47.78 Minutes

Laser:  (45.93/91.3)*100   = 50.30 Minutes

Thistle:  (48.00/83.0)*100  = 57.83 Minutes

4) Finally, rank based on CT, and the “winner” is the National One-Design with a Corrected Time (CT) of only 47.78 minutes.  The Thistle is a distant “last” with a CT of 57.83 minutes.