user: Question: How many sail numbers for boat skippered by Geoff Ross?
Columns: ['Position', 'Race number', 'Sail number', 'Yacht', 'State/country', 'Yacht type', 'LOA (Metres)', 'Skipper', 'Elapsed time d:hh:mm:ss']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'X1', '10001', 'Wild Oats XI', 'NSW', 'RP100', '30.00', 'Mark Richards', '1:20:34:14']
SQL:

assistant: SELECT COUNT("Sail number") FROM "Table" WHERE "Skipper" = 'Geoff Ross';