Winning isn't everything

The situation

Already well clear in the lead, a sailor deliberately turns back to sit on a rival from another club and slow her down out of spite — with no benefit to his own race.

The question

Is there a rule against deliberately spoiling someone's race even if you 'win' the boat-on-boat?

The ruling

Yes. Rule 2 (Fair Sailing) requires boats to compete in accordance with recognised principles of sportsmanship and fair play, and rule 23.2 says that, if reasonably possible, a boat shall not interfere with a boat sailing on another leg — after the starting signal, only a boat sailing her proper course is excused. Deliberately and maliciously interfering — or intentionally breaking a rule — can be penalised under rule 2 even where no Part 2 rule was technically broken, and a rule 2 penalty is normally a disqualification that can't be dropped. Sail hard, but sail fair.