Safety Instructions and Regulations at Sea To ensure safety at sea, vessels must observe the navigational safety instructions and regulations. For example: When two vessels meet, the moving vessel should give siren signal to show its intention. 1 short siren signal : Vessel is turning right 2 short siren signals : Vessel is turning left 3 short siren signals : Vessel is going backwards Short siren signal : lasts for about 1 second Long siren signal : lasts for 4-6 seconds Vessels can also use light signal to supplement the siren signal. Light signals can be repeated if appropriate. Different light signals have different meanings : 1 spark of light : Vessel is turning right 2 sparks of light : Vessel is turning left 3 sparks of light : Vessel is going backward Each spark of light should last for one second and one second should be left in between the two sparks of light. In case of narrow water passageway, a vessel must give siren signal to show its intention of getting over the other vessel. 2 long, 2 short : Vessel will get over on the left 2 long, 1 short : Vessel will get over on the right For the ship that is being get over, it should show its consent by giving the following siren signals, One long, one short, one long, one short.