The windward boat protests for room
The situation
Approaching the committee boat to start, Blue is overlapped to windward of Green and runs out of room. The boats touch, Blue can't fit, and Blue protests — “Green never gave me room at the mark!”
It's a mark, Blue is the inside boat, and she got squeezed out with nowhere to go — surely Green owed her mark-room and is the one who fouled.
The question
Whose protest succeeds — Blue's, or does it flip onto her?
The ruling
It flips onto Blue. Rule 18 does not apply at a starting mark surrounded by navigable water while boats are approaching the line to start (Section C preamble), so Blue is owed no mark-room at all. That leaves plain rule 11: Blue, to windward, must keep clear of Green. By barging into a gap that wasn't there she broke rule 11 — and her protest only gets herself penalized. Green sails on.
There is no mark-room at a starting mark — the windward barger keeps clear, and her own protest sinks her.
Opens the situation on the boat-length grid — scrub it and see exactly how the boats meet. Free, no account needed.
Rules cited
See the underlying rule: Rule 18.1 — No Room to Barge at the Start.