Content:
IRC
Time-Difference Table (interactive)
Understanding IRC
Handicap
IRC
TCC
Handicap Table (Unofficial
Ratings)
IRC
Time-Difference Table
To generate time-differences and calculate elapsed times
between you and your competition please use the following tool:
Web
site:
Time-Difference
Comparison Tool
(Created
by L. Kahl, Interactive Creations)
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Understanding IRC
Handicap Differences
“ARE WE
WINNING?”
Simplistically,
each 0.001 of rating difference between two boats represents a corrected
time difference of approximately
3.6 seconds per hour. This will however only be absolutely
correct for boats rating very close to 1.000. So how can you be certain
whether you are beating your rivals on the race course?
Starting with
boat A rating 1.010 and boat B rating 0.995, if Boat A sails for one
hour, her corrected time will be 1.010 hours which is 1:00:36 (1 hour 0
minutes 36 seconds). Boat B will beat Boat A if her corrected time is
less than that. To find out what this means in terms of time, we want to
find Boat B’s maximum elapsed time. To do this divide Boat A’s
corrected time by Boat B’s rating - 1:0:36 / 0.995 = 1:00:54. In other
words Boat B can sail for up to an extra 54 seconds before her corrected
time is more than boat A's. An easier way of doing the same thing is to
divide the rating of boat A by the rating of boat B – ie 1.010/0.995 =
1.015 and 1.015 hours is 1:00:54.
Notably,
boats A and B have a rating difference of 0.015, thus confirming (54/15
= 3.6) the 3.6 seconds per 0.001 noted above. But if the boats are
faster or slower, while the maths remains the same, the answer starts to
vary from 3.6. If boat C rates 1.110 and boat D rates 1.095 (the same
rating difference of 0.015 as A and B) the time difference for an
hour’s racing is 1.110/1.095 = 1.0137 which is 1:00:49 – equivalent
to 3.27 seconds for each 0.001.
Similarly,
boat E rates 0.910 and boat F rates 0.895 (again 0.015 less). The time
difference for an hour’s racing by Boat E is 0.910/0.895 = 1.0168
which is 1:01:00 – equivalent to 4.0 seconds for each 0.001.
For
a given fleet of boats, this can then be dealt with by creating a table
of time allowances for the fleet
|
|
IRC
|
Time Differences in seconds for various
race durations
|
|
|
Yacht
|
TCC
|
1 hr
|
2 hr
|
10 min
|
20 min
|
30 min
|
|
|
|
|
|
|
|
|
|
Alpha
|
1.190
|
222
|
443
|
37
|
74
|
111
|
|
Beta
|
1.169
|
154
|
308
|
26
|
51
|
77
|
|
Gamma
|
1.158
|
119
|
238
|
20
|
40
|
59
|
|
Delta
|
1.137
|
51
|
103
|
9
|
17
|
26
|
|
Epsilon
|
1.134
|
42
|
83
|
7
|
14
|
21
|
|
Zeta
|
1.132
|
35
|
71
|
6
|
12
|
18
|
|
You
|
1.121
|
0
|
0
|
0
|
0
|
0
|
|
Eta
|
1.121
|
0
|
0
|
0
|
0
|
0
|
|
Theta
|
1.108
|
-42
|
-83
|
-7
|
-14
|
-21
|
|
Iota
|
1.108
|
-42
|
-83
|
-7
|
-14
|
-21
|
|
Kappa
|
1.105
|
-51
|
-103
|
-9
|
-17
|
-26
|
|
Lambda
|
1.103
|
-58
|
-116
|
-10
|
-19
|
-29
|
|
Mu
|
1.092
|
-93
|
-186
|
-16
|
-31
|
-47
|
The
table above is the ideal way to deal with this. For occasions when you
do not have this for whatever reason, another simple way of dealing with
it is to divide 3.6 by your TCC. eg, 3.6/1.100 = 3.3 seconds or
3.6/0.900 = 4.0 seconds. The answer in each case will then be closer to
the correct time allowance per 0.001 rating difference between your boat
and a reasonably closely rated competitor. The answer will still be approximate,
but rather better than just using 3.6!
Mike
Urwin
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