The default sequence is five minutes long, and the flags are what count. Time is taken from the visual signals; if a gun misfires or a horn fails, ignore the missing sound.
- Warning, 5 minutes: class flag up, one sound.
- Preparatory, 4 minutes: P, I, Z, Z with I, U or black flag up, one sound.
- One minute: preparatory flag down, one long sound.
- Start, 0: class flag down, one sound.
The notice of race or sailing instructions may change the warning-signal time (three-minute sequences are common for dinghies). Each following class's warning comes with or after the previous class's start.
Common situations
Sound and flag disagree
Start your watch on the flag. If the horn is late by two seconds, the flag still governs.