Rules of the Road.
Rule 32. Sound & light Signals
Definitions
(B) The Term "short blast" means a blast about one seconds duration.
(c) The Term "prolonged blast" means a blast of four to six seconds duration.
Rule 34 Maneuvering and Warning Signals
International. (a)One Short blast means "I am altering my course to starboard" (right)
Inland. (a) One Short blast means "I intend to leave you on port side" (left)
Stay out of the way! One prolonged blast is the whistle signal for a ship leaving a berth or in a blind bend in a channel.
Runaway ship
Vessel operators can alert the lock attendant of their request to transit through the lock by sounding one prolonged blast followed by one short blast
You are operating a motorboat. You hear one prolonged blast from the horn of another vessel. What should you do?
B
one prolonged blast
You should go left
Rules of the Road.Rule 34Maneuvering and Warning signalsInternational(e) A vessel nearing a bend or an area of a channel or fairway where other vessels maybe obscured by an intervening obstruction shall sound one prolonged blast. Such signal shall be answered with a prolonged blast by any approaching vessel that maybe within hearing around a bend or behind the intervening obstructionRule 34Inland(g) When a power driven vessel is leaving a dock or a berth, she shall sound one prolonged blast.
The sound signals that it is a sailing vessel underway when you hear one prolonged blast plus two short blasts every two minutes.
One prolonged blast means a sound signal of between 4 and 6 seconds. By itself it to notify other users of the presence of a vessel that is manoeuvring. Leaving a dock or if obscured by something for instance.
blind bend
The Vessel is turning to Starboard .