))TIME ON TIME SCORING IN PHRF
John Collins
The vast majority of handicap racing in North America is scored by the
Time on Distance (TOD) method. Here a fixed time allowance, based on
the length of the course, is used to compute the corrected time. An
advantage of TOD is that is simple and you can tell exactly where you
stand at any point in the race.
In Europe the Time On Time (TOT) scoring method is popular. Here the
time allowance for a given race depends on the time of the race. The
reasoning being that smaller boats are at a disadvantage if the race is a
slow race if the time allowance doesn’t change to account for the
conditions of the race. This TOT method is only slightly harder to
understand than TOD as the allowance at any point in the race can be
affected by a change of conditions later in the race.
Over the past few years a number of PHRF fleets have started using TOT
scoring. It has been found to help some when there is a very large
handicap spread in a class or if the race conditions are “abnormal”. The
following is a TOT conversion formula that is commonly used to convert
the standard PHRF TOD handicap into a TOT Time Correction Factor
(TCF).
A
TCF = ------------------
B + PHRF
The denominator, B + PHRF, is the number of seconds it takes to sail a
nautical mile in the expected conditions. Another way to look at it is that the
denominator divided into 3600 is the average boat speed in knots. Here
are some commonly used B factors:
B Factor
When used
480
Heavy air or all off the wind
550
Average conditions
600
Very light air or all windward
work
The numerator, A, is merely a coefficient that makes a “nice” looking TCF.
Select it so that the TCF for the middle of the fleet is about 1.000. The A
coefficient has absolutely no effect on the corrected finish order. Changing
it will only affect the various margins. Thus if your middle handicap is about
100 and your conditions are average, then the TCF formula would look like
the following:
650
TCF = ------------------
550 + PHRF
To get the corrected time, simply multiply the elapsed time by the TCF.
TOT scoring is not a cure-all for all the inequities of handicapping. TOT
scoring will not turn a fleet upside down. It usually does not affect the top
boats. It usually moves the boats in the middle around a little. If the
handicap spread in a class is large, it will tend to tighten things up a bit.
carrds@us.ibm.com