A boat blocked my tack and my gybe and left me behind the start — isn't that illegal?

No — Rule 16.1 (give room when you change course) only restricts the right-of-way boat, and the boxed-out boat never had right of way. Driving a rival away from the line is a legal pre-start move; being blocked is not, by itself, breaking a rule. (World Sailing Case 52.)

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