1 short blast (1 second) : I want to pass you on my port side (Hint: PORT = 1 syllable = 1 short blast)
2 short blasts : I want to pass you on my starboard side (Hint: STARBOARD = 2 syllables = 2 short blasts)
3 short blasts : Engine is in reverse
5 short blasts : Danger, or do not understand approaching boat's intentions
1 prolonged blast (4-6 seconds) Warning :
1) Entering or exiting a blind turn
2) Nearing an obstructed area
3) Leaving a dock or a berth
1 prolonged blast every 2 minutes : Power-driven vessel operating in low or restricted visibility
1 prolonged blast + 2 short blasts every 2 minutes : Sailing vessel operating in low or restricted visibility