Official NHA Assessment

Race 4: SA DERBY 4 APRIL MAIDEN PLATE (For all Maidens)

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Line Horse
Slender Silhouette
Reference for assessment
Exact Matches
0 / 8
Calculated = Official
Close Matches
1 / 8
Within 2 points
Significant Diffs
4 / 8
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    Slender Silhouette   2    57.5    1    0.00     2.5   75    75           75    +0
2    Sosoru               3    60.0    2    0.90     3.5   -     78           78    +78
3    Hammer Blow          3    60.0    3    2.20     3.5   73    78           78    +5
4    Isaac Stephan        3    60.0    4    9.50     3.5   -     78           78    +78
5    Wish You Were Here   3    60.0    5    11.75    3.5   -     78           78    +78
6    Scorpio              2    60.0    6    12.00    2.5   75    80           80    +5
99   Gunboat              3    60.0    99   0.00     3.5   -     78           78    +0
99   Jawbreaker           3    57.5    99   0.00     3.5   -     73           73    +0
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Horse-by-Horse Comparison

Pos Horse Pre-Rating Official New Calculated Discrepancy WFA (kg) Line Horse Calculation
1 Slender Silhouette Line 75 77 75 +2 2.5
2 Sosoru - - 78 -78 3.5 -
3 Hammer Blow 73 74 78 -4 3.5 -
4 Isaac Stephan - - 78 -78 3.5 -
5 Wish You Were Here - - 78 -78 3.5 -
6 Scorpio 75 75 80 -5 2.5 -
99 Gunboat - 74 78 -4 3.5 -
99 Jawbreaker - 62 73 -11 3.5 -
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