Official NHA Assessment

Race 6: HF OPPENHEIMER HORSE CHESTNUT STAKES (Grade 1) (Weight for Age)

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Line Horse
Under Your Spell
Reference for assessment
Exact Matches
0 / 11
Calculated = Official
Close Matches
4 / 11
Within 2 points
Significant Diffs
6 / 11
More than 5 points
Detailed Assessment
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Pos  Horse                Age  Weight  Fin  Lengths  WFA   Pre   Race Rating  New   Adj  
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1    Trip Of Fortune      3    60.0    1    0.00     2.5   119   117          117   -2
2    Mk's Pride           4    60.0    2    1.25     1.0   120   124          124   +4
3    Anfields Rocket      5    57.5    3    2.35     0.0   118   119          119   +1
4    Under Your Spell     3    57.5    4    2.85     2.5   114   114          114   +0
5    Bingwa               7    60.0    5    3.35     0.0   123   123          123   +0
6    Gimme A Shot         2    55.0    6    3.60     0.0   112   113          113   +1
7    Puerto Manzano (ARG  4    60.0    7    4.00     1.0   123   121          121   -2
8    Red Saxon            3    60.0    8    7.00     2.5   116   117          117   +1
9    Thunderstruck        2    57.5    9    8.30     0.0   115   117          117   +2
10   Golden Ducat         6    60.0    10   21.00    0.0   120   122          122   +2
99   Melech               5    57.5    99   0.00     0.0   -     117          117   +0
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Horse-by-Horse Comparison

Pos Horse Pre-Rating Official New Calculated Discrepancy WFA (kg) Line Horse Calculation
1 Trip Of Fortune 119 127 117 +10 2.5 -
2 Mk's Pride 120 116 124 -8 1.0 -
3 Anfields Rocket 118 106 119 -13 0.0 -
4 Under Your Spell Line 114 113 114 -1 2.5
5 Bingwa 123 107 123 -16 0.0 -
6 Gimme A Shot 112 110 113 -3 0.0 -
7 Puerto Manzano (ARG) 123 119 121 -2 1.0 -
8 Red Saxon 116 116 117 -1 2.5 -
9 Thunderstruck 115 128 117 +11 0.0 -
10 Golden Ducat 120 116 122 -6 0.0 -
99 Melech - 118 117 +1 0.0 -
Assessment Methodology
Calculation Steps:
  1. Identify Line Horse - consistent performer used as reference
  2. Calculate WFA Allowance based on age, distance, and month
  3. Apply Drag Adjustment for beaten margin
  4. Calculate Actual Weight Performance:
    Weight - Drag - WFA
  5. Compare to Line Horse to determine race rating
  6. Apply special rules (maiden caps, layoff allowance)
Key Formulas:
  • Drag Effect: Varies by distance (see Benchmarks page)
  • 1 length ≈ 1kg at 1 mile (1600m)
  • WFA Scale: Based on Admiral Rous's 1855 table
  • Rating Points: 1kg = 2 rating points