it is the same right
It means a vessel is going to back up.
Two short horn blast from a vessel means that she is turning port and one short horn blast that she is turning starboard
They can swim backwards in short bursts, if that's what you mean.
Three short blasts tell other boaters, “I am operating astern propulsion.” For some vessels, this tells other boaters, “I am backing up.”
A. Three long blast of the ships whistle or general alarm at an interval of three, means a man overboard. This is dismissed by three short whistle blast. B. Three Short blast can also be Rule 34 (Inland and International) "Maneuvering and Warning Signals." Three short blast means "I am operating astern propulsion."
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.
I intend to pass you on my starboard (right) side.
passing on port side
Passing on your starboard (right) side.
I intend to pass you on my starboard (right) side.
Means it's about to turn to port.