RRS Rule 30.4 (Black Flag Rule): a boat that breaks the rule is disqualified without a hearing (BFD). A plain BFD is an ordinary disqualification and is excludable, so the discard rules may drop it like any other worst score. (The only non-discardable variant is the niche case of a boat that sailed a restart after being black-flagged, scored DNE — not modelled here.) Under default A5.2 scoring BFD scores entries+1 (5 boats → BFD = 6). With 1 discard allowed, Alice's BFD is her worst score and is dropped.
Scoring configuration: 1 discard from race 4. DNF/OCS scoring: A5.2 (series entries).
Alice gets BFD — worst score (6 pts) and, being a plain disqualification,
discardable: her one discard drops it.
Bob gets a normal 4 in race 4; his worst (4) is discarded.
Alice: R1=1, R2=1, R3=1, R4=6(BFD). Total=9. Discard worst=6(BFD). Net=3.
Bob: R1=2, R2=2, R3=2, R4=4. Total=10. Discard worst=4. Net=6.
Carol: R1=3, R2=3, R3=3, R4=3. Total=12. Discard worst=3. Net=9.
David: R1=4, R2=4, R3=4, R4=2. Total=14. Discard worst=4. Net=10.
Eve: R1=5, R2=5, R3=5, R4=1. Total=16. Discard worst=5. Net=11.