Question

What does one prolonged blast plus one short blast signal to a river lock attendant?

Answer 1

You want to go through the lock

Step-by-step explanation:

When an individual or sailor is nearing the Lock, s/he can delay movement for at least about 130 meters away from the lock, such that the signal can enter the lock. Thus, an individual will then notify or alert the lock attendant that s/he wish to pass through the lock. To achieve this, the sailor will then sound one prolonged blast followed by one short blast of ones boat's sound-producing device.

Answer 2

When you are approaching a river lock, you are expected to sound one prolonged blast and one short one in order to signal to the lock attendant that you want to pass through. You are to sound the blast when you are about one mile away from the river lock. The attendant will reply you with one of the traffic signals in order to instruct you about what to do.