Pin Me

Emergency Situations on Ship : Oil Spills - II

written by: Raunekk • edited by: Lamar Stonecypher • updated: 6/27/2011

Do you know how much oil can a ship discharge in sea water? and where? If not just read this this article where we will learn about the different ways and measures to control oil pollution from ships.

  • slide 1 of 5


    In the previous article we saw the various causes for the occurrence of an emergency situations and also for oil spillage. We also had a brief overview of the possible adverse consequences of marine oil pollution on environment and also on human life. In this article we will list down the various steps we need to take to prevent and control oil pollution done by ships. We will also have a brief gist of the marine pollution prevention act (MARPOL) and its various ammendments pertaining to oil pollution by ships.

  • slide 2 of 5

    Control of discharge of oil.

    There are certain conditions which needs to be taken into consideration if there arises a necessity to discharge oil into the sea. Let's go through these conditions.

    Special areas

    Special areas are those parts of the sea that are considered extremely sensitive to oil or any kind of pollution. They are recognized special due to technical reasons in relation to their oceanographical and ecological conditions or due to the particular characteristics of their traffic. These special areas include Mediterranean Sea, Baltic Sea, Red sea, Gulf area, black sea, Gulf of Aden and Antarctic area.

  • slide 3 of 5

    How much to discharge?

    How much to discharge? (for special areas)

    You cannot discharge any kind of oil or oily water in sea in the special areas but incase it is necessary to do so, there are few conditions that needs to be followed.

    The bilge water or any water that needs to be discharged shouldn’t originate from cargo spaces or is mixed with any kind of cargo residue. The ship should be proceeding en route. All the oil filtering and monitoring equipments should be intact and in proper working condition. The oil content of the effluent that is not diluted shouldn’t exceed 15 ppm (parts per million) and incase it exceeds 15 ppm the stopping device should stop the discharge automatically and immediately.

  • slide 4 of 5

    How much to discharge?( for tankers and other ships)

    Oil discharge from machinery space bilges and oil fuel tanks

    It is inscribed in MARPOL that you cannot discharge oil into the sea, not even a single drop. But if you want to discharge oil into the sea, the vessel should be provided with oily water separating and oil filtering equipments. This instrument should separate oil from water and can discharge water with not more than 15 ppm (parts per million) of oil in it. In the event of malfunctioning of the equipment, alarm should sound and the discharge be stopped automatically.

    For oil tankers( 400GT and above)

    Any kind of oil discharge into the sea is prohibited and if it should be done then there are conditions that should be followed.

    For all the oil tankers or ships with 400 GT (gross tonnage) and above, few points should be kept in mind incase discharging of oil is necessary.

    During the discharge, it should be noted that the ship is not in any of the special areas. Also the area where the discharge is to be made is more than 50 NM (Nautical miles) away from the nearest land. It is imperative that the ship is proceeding en route.

    The rate and quantity of discharge is also to be kept in check. The instantaneous rate of discharge of oil content shouldn’t exceed 30 k per nautical mile. Also of the total quantity oil discharged into the sea, residue formed shouldn’t be more than 1/15000 of the total quantity of the particular cargo, for existing ships and 1/30000 for new ships. An Oil discharge monitor and control system in proper working condition is a must on ship

    For ships other than tankers ( 400 GT and above).

    For ships that are not tankers, all the rules except a few, are same.

    It should be noted that the ship is not within a special area. Also the area where the ship wants the discharge should be more than 2 NM from the nearest land and is proceeding en route. Oil content of the effluent should be less than 100 ppm and the oil discharge monitor and control system should be intact.

  • slide 5 of 5

    Other necessities

    Oil record book is an indispensable entity on board a ship. In case of any kind of operational flaws or mishaps, it is the first thing which is referred to. It is supposed to have a record of exact quantities of all the oils present on board. Correct and precise entries are expected to be made in it. Entries of quantities involving activities such as ballasting or cleaning of oil fuel tanks discharge of dirty ballast and water from tanks, disposing of oil residues and discharge of bilge water that is accumulated in the machinery spaces is made in it.

    Oil record of the oil present in the tank at the time of loading and unloading of oil should be made. Records of individual tanks incase of oil transfers between internal tanks. Also records of discharge at the time of crude oil washing, discharge from ballast tanks and from slop tanks,and discharge of residues should be precisely made.

    In the next article we will learn about the various steps and procedures that are undertaken to prevent marine oil pollution by oil spills.