It is called a short salute and is how ships greet each other.
Three short blasts means you are operating in reverse. One prolonged blast followed by 3 short blasts means boat under tow in redcued visibility conditions.
Passing on your right side.Signals are (number of blasts):1. Passing you on your left (port) side2. Passing you on your right (starboard) side3. I am moving backwards (astern)4. Danger, don't do that (answer to the other three if dangerous)One short blast means 'I am changing course to starboard.'Two short blasts mean 'I am changing course to port.'Three short blasts mean 'I am operating astern.'Two prolonged blasts followed by one short blast to mean 'I intend to overtake you on your starboard side';Two prolonged blasts followed by two short blasts to mean 'I intend to over-take you on your port side.'A long blast every two minutes is used when operating in fog.
on short blast
Sailboat
three short blast
1 short blast to pass on YOUR port side.
Two short blasts mean that one intends to overtake the other on the port side. One short blast, on the other hand, means that one intends to overtake the other on the starboard side.
Don't know what it means, but five short blasts from the hoRN must be a warning of some kind?
The sound signals that it is a sailing vessel underway when you hear one prolonged blast plus two short blasts every two minutes.
7 or more short blasts on the ship whistle and general alarm bell followed by one prolonged blasts
When visibility is very limited, such as in heavy fog, boaters must give an audible signal to others in the area. For a sailboat the signal is one prolonged blast plus two short blasts every two minutes.
Two short blast shows the intention to direct the course of their vessel to their own port (left).