You fouled someone — now what?

The situation

Beating upwind, Jonah on port tack doesn't quite clear a starboard-tack boat, who has to luff sharply to avoid him. There's no contact and no damage, but Jonah knows he broke the rule.

The question

Can Jonah keep racing, or is he out?

The ruling

He can stay in the race by taking a penalty. Under rule 44, a boat that breaks a rule of Part 2 (here rule 10) may take a Two-Turns Penalty: get well clear of other boats, then promptly make two tacks and two gybes — two full circles — in the same direction. Doing the turns voluntarily clears the foul. If he'd caused injury or serious damage, rule 44.1(b) would require him to retire instead.