Complex sentence: In England the sails were white cotton until a proofing coat was applied usually after the sail was a few years old this gave the sails its distinctive red ochre colour, which made them a picturesque sight in large numbers.
Split into simpler sentences: In England the sails were white cotton until a proofing coat was applied, usually after the sail was a few years old. This gave the sails its distinctive red ochre colour, which made them a picturesque sight in large numbers.