What is the signal that the ship is three long and one short?

This signal is a voice signal between ships.

This signal is used to indicate an emergency or to warn other ships. It means "I have difficulty in manipulation and need your help". Three long and one short message signals are sent by the ship's communication equipment, usually by radio or flute to other ships. Other ships will respond immediately after hearing this signal, such as providing help to their own ships, adjusting their course or slowing down.

In maritime navigation, the signal of three long and one short ships is a very common voice signal, which is used to ensure the safety and coordination between ships. All ships should pay close attention to this signal and respond in time to ensure the safe and smooth navigation at sea.