A boat is astern propulsion and is in the act of backing up
it is the same right
three short blast
I intend to pass you on the starboard(right) side
Three short blasts tell other boaters, “I am operating astern propulsion.” For some vessels, this tells other boaters, “I am backing up.”
Three short blasts of a horn on a boat typically indicate that the vessel is operating in reverse. This signal is used to communicate the boat's intentions to other vessels in the vicinity, ensuring safety and preventing collisions. It’s important for all boaters to understand these sound signals as part of navigational rules.
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.
you are altering your course to starboard
A vessel that is backing up typically uses a series of short blasts on its horn to alert other boats of its intention to maneuver in reverse. This sound signal consists of three short blasts, which indicate that the vessel is preparing to move backward. This is part of the International Regulations for Preventing Collisions at Sea (COLREGs) to ensure safety on the water.
I intend to pass you on my starboard (right) side.
They are indicating dangerous
Means it's about to turn to port.
Passing on your starboard (right) side.