You are overlapped on the inside of another boat at the leeward mark, so she owes you mark-room. You sail on past the mark, deep and wide, and your boom hits her as she rounds. She owed you room, so is it her fault?
No. Mark-room (Rule 18.2) is room to sail to the mark, round it and leave it astern, manoeuvring promptly in a seamanlike way. It is not room to swing as wide as you like. Once you take more than that, you are no longer sailing within the mark-room you are entitled to, so it gives you no protection. You are simply the windward boat on the same tack, overlapped, and Rule 11 says a windward boat keeps clear of a leeward boat. You broke rule 11. The outside boat's turn up onto the new leg is steady, so she gives you room to keep clear (Rule 16.1). Under Rule 14 she must avoid contact if reasonably possible, but a right-of-way boat need not act until it is clear the other boat is not keeping clear, and with no damage or injury she is exonerated anyway (Rule 43.1(c)). Inside at the mark, you get room to round, not room to roam.
📖 Want Rule 18 in more depth? Elvstrøm Explains the Racing Rules 2025-2028 sets out every rule with plain-English explanations and diagrams. (affiliate link)
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<p><a href="https://sailing.kiwi.nz/v/qprlt4E61uM/">Source: Sailing Kiwi</a></p>Go deeper: books and gear
- Elvstrøm Explains the Racing Rules 2025-2028 — Every rule, with plain-English explanations and diagrams.
- Racing Rules Companion 2025-2028 by Bryan Willis — Spiral-bound pocket guide to the current rules.
- Tactics Made Simple by Jon Emmett — Racing tactics, explained simply.
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