Worldwide Analysis of In-Port Vessel Operational Lubricant 

Discharges and Leakages

Dagmar Schmidt Etkin

Environmental Research Consulting

41 Croft Lane

Cortlandt Manor, NY 10567-1160 USA

etkin@environmental-research.com

Abstract

The majority of ocean-going ships operates with oil-lubricated stern tubes and 

uses lubricating oils in a large number of applications in on-deck machinery and inwater (submerged) machinery. The issue of oil leakage from stern tubes, once 

considered a part of normal “operational consumption” of oil, has become an issue of 

concern and is now being treated as oil pollution with full legal consequences. 

Greater focus on stern tube leakage and the spillage of other types of lubricants used 

in marine shipping operations have led to a need to evaluate alternatives to these oils 

and ways to monitor and prevent discharge of lubricants during ship operations in 

ports and at sea.

This study focuses on marine inputs of lubricant oils within the 4,708 ports 

and harbours of the world through stern tube leakage and operational discharges in 

marine shipping. The study results indicate that, overall, the results indicate that each 

year in over 1.7 million vessel port visits, 4.6 to 28.6 million litres of lubricating oil 

leaks from stern tubes, and 32.3 million litres of oil is input to marine waters from 

other operational discharges and leaks. 

Total estimated response and damage costs for lubricating oil leaks and

operational discharges worldwide based on the probabilities of leakage and 

operational discharge by vessel type in the 4,708 ports worldwide are estimated to be 

between US$322 million for conventional lubricating oils.

1 Introduction

The majority of ocean-going ships operates with oil-lubricated stern tubes and 

uses lubricating oils in a large number of applications in on-deck machinery and inwater (submerged) machinery. The issue of oil-based lubricant discharges into the 

marine environment has been raised by various studies, most notably GESAMP 

(2007), which found that 457 million litres of oil enter the oceans a year from regular 

shipping activities, though this study specifically did not include lubricant discharges 

during normal ship operations.

Basic calculations presented at International Maritime Organization (IMO) 

Marine Environment Protection Committee (MEPC) (IMO MEPC, 2008) meetings 

estimated that 80 million litres of oil-based lubricants are lost at sea annually from 
stern tubes alone. However there have been as yet no authoritative figures on this or 

other lubricant pollution to guide delegates and policymakers. 

2 Methodology

This study focuses on operational discharges of lubricant oils within ports and 

harbors including discharges that occur during transit within the harbor or port and 

while moored at docks. The study excludes inputs that occur en-route or on the open 

ocean, since the monitoring and recording of small discharges at sea is relatively poor 

making any data analyses on these types of inputs extremely inaccurate.

The study also only includes the leakage, and operational discharge of these 

lubricants in their application and use in marine shipping (i.e., on the ships 

themselves as stern tube lubricants, gear lubricants, etc.). It specifically excludes

accidental spills from vessels (e.g., during a collision) or spills of stored lubricant oils 

at shore-based facilities or the transport of these lubricants as cargo by tank ships, 

tank barges, railroad, or tanker truck, or inputs from land-based lubricants using 

similar machinery, e.g., cranes, as those considered on vessels. Spills are defined as 

discrete events in which oil is released accidentally, or, occasionally, intentionally 

through dumping or vandalism, over the course of a relatively short amount of time. 

Spillage can occur during transfers (e.g. in refilling lubricating oil vesicles), as a 

result of accidents, such as a collisions, allisions, or groundings, or there is significant 

structural damage to the vessel.

Two types of lubricating oil inputs are included in the study – stern tube 

leakages and operational discharges. Inputs are estimated based on port visit data by 

vessel type for 4,708 ports worldwide, as well as by nation.

Lubricant spills and releases come from a number of different sources on a 

vessel and it is worthwhile considering the two separately. Focus in the past has 

always been upon the highly visible spills that take place, with hydraulic fluids being 

the primary area of concern, as these systems operate at high pressures and high flow 

rates. They incorporate elastomer seals and flexible hoses that are subject to wear and 

abrasion, and also to fatigue with continual pressure fluctuations. When a hose bursts,

there is a significant amount of oil released onto the deck and then onto the sea, 

where its presence is very obvious. Similarly leaks from smaller items of deck 

equipment such as winches and windlasses are very evident. The gearboxes on this 

equipment are not generally pressurised, but leaking seals on shafts result in gear oil 

leakage onto the deck and again it makes its way over the side. These occasional 

spills or leaks are easily evident because they result in a sheen on the water surface –

in port, at least.

2.1 Stern Tube Leakage

Stern tube leakage is significant source of lubricant oil inputs to the marine 

environment. A 2001 study commissioned by the European Commission DG Joint 

Research Centre (Pavlakis et al., 2001) reported on the extent of ship-based oil 
pollution in the Mediterranean Sea. The study revealed that routine unauthorized 

operational discharges of oil created more pollution than accidental spills. Stern tube 

leakage was identified as a major component of these discharges.

The stern tube of a ship is the connection between the engine and the 

propeller. Inside the stern tube is the propeller shaft, which is driven by the ship’s 

engine and rotates to turn the propeller round. The stern tube is one of the parts of a 

ship below the waterline that contains a significant amount of lubricant oil.

Generally, stern tube shaft seals are the only barrier between the oil in the 

stern tube and the marine environment. A propeller shaft sealing system is designed 

to prevent the entry of water into the stern tube where it could damage the bearings. 

The seal is also designed to prevent the leakage of lubricating oil into marine waters. 

Ideally, in this closed system there should be no leakage to the water.

According to the US Environmental Protection Agency (EPA, 1999), “oil 

lubricated stern tube seals cannot release oil to the environment under normal ship 

operations”. Some common system design features to prevent releases include :

Use of multiple sealing rings at both the inboard and outboard stern tube ends;

Methods to maintain pressure in the stern tube cavity below that of the sea 

water pressure outside to ensure that in the event of leakage, water will leak in 

rather than any lubricant leaking out; and

Positive methods for determining stern tube seal leakage.

Because these seals can become worn over time or damaged by marine debris, 

particularly rope and fishing lines, oil leakage can occur. Anecdotal and empirical 

evidence from stern tube lubricant consumption supports this contention. The issue of 

oil leakage from stern tubes, once considered a part of normal “operational 

consumption” of oil, has become an issue of concern as it is now being treated as “oil 

pollution” with the same legal consequences as spills in many jurisdictions (e.g., 

under the US EPA 2008 National Pollution Discharge Elimination System or 

“NPDES” regulations implemented in 2009).

There are no completely reliable estimates or methodologies for estimation of 

stern tube leakage. Clearly, stern tube leakage varies by vessel type, condition, age, 

and maintenance. Based on on-site inspections, leakage rates are observed to vary 

with vessel age, especially for stern tubes in older vessels that have been damaged by 

ropes or fishing nets, and for which maintenance may be a lower priority. There are 

anecdotal reports of newer vessels rarely requiring stern tube lubricant top-off. 

Theoretically, with a closed stern tube system there should be no leakage, but 

observations indicate that there is “rarely a perfectly sealed system” and that there is 

always some small amount of leakage. It is also not uncommon for older vessels to 

require 5 – 10 litres per day.

The leakage rate for stern tubes has been widely reported as “6 litres per day” 

for a vessel of 1,000 DWT, with higher rates for larger vessels and lower rates for 

smaller vessels(Thorndon, 2004; Carter, 2009; Ahlbom and Duus, 2006; IMO 
MEPC, 2008). This reported leakage rate has been explained as being based on the 

maximum allowable leakage for certification in Lloyd’s Registry Class Society Seal 

Type Approvals for vessels of at least 1,000 deadweight tonnage (DWT), though all 

classification societies mention leak tests and “zero tolerance” for leakage. According 

to the Clean Shipping Project of Sweden (Ahlbom and Duus, 2006), there is a “rule of 

thumb” that up to one percent of the thickness in millimeters of the stern tube seal is 

an acceptable leakage level when counted as litres per 24-hour period. For a 600 mm 

seal, this means 6 litres per day. To put these leakage rates into perspective, it is 

instructive to consider the degree to which such discharges may be noticed by port 

authorities if not by vessel operators. In the US, the acceptable discharge limit (as per 

40 Code of Federal Register (CFR) part 110) is that quantity that does not create a 

noticeable sheen (i.e., a rainbow sheen with an average thickness of 0.0003 mm or a 

silver sheen with an average thickness of 0.0001 mm). One litre of oil would spread 

to a rainbow sheen covering about three m2. Six litres would cover 20 m2. This would 

likely be noticed by port officials and require a response. 

An analysis of data on oil consumption sourced from a lubricant supplier 

indicates a range of average daily stern tube lubricant consumption rates for different 

vessels. The average rate across vessel types is 2.6 litres per day, but ranges from less 

than 1 litre per day to 20 litres per day. The results of the stern tube consumption data 

analysis are summarized in Table 1. 

Table 1. Average Daily Consumption of Stern Tube Lubricants

Vessel Type(s)1 Daily 

Consumption 

Barge Carrier 20 litres/day

IWW Oil Tanker 11 litres/day

Navy Ships 10 litres/day

General Cargo Ship 7 litres/day

Bulk Carrier; Passenger/Ro-Ro Cargo Ship 6 litres/day

Container Ship; Tender; Live Stock Carrier 5 litres/day

Heavy Load Carrier; Research Vessel; Crude Oil Tanker; Refrigerated Cargo Ship; 

Chemical Tanker; Container Ro-Ro Cargo Ship; Trawler 4 litres/day

Pusher Tug; Hopper Dredger; Palletised Cargo Ship; Oil Products Tanker; Wood 

Chips Tanker; Chemical/Oil Products Tanker; Vehicles Carrier; LPG Tanker 3 litres/day

Offshore Supply Ship; Passenger Ferry; Self-Discharging Bulk Carrier; Offshore 

Tug/Supply Ship; Fish Carrier; Fishing Vessel; Sail Training Ship; Passenger Cruise 

Ship; Standby Safety Vessel; Cement Carrier; Asphalt/Bitumen Tanker

2 litres/day

Offshore Support Vessel; Bulk/Oil Carrier; LNG Tanker 1 litre/day

Buoy/Lighthouse Vessel; Cable Layer; Crane Ship; Dredger; Fishery Support Vessel; 

Live Fish Carrier; Motor Hopper; Offshore Processing Ship; Ore Carrier; 

Passenger/General Cargo Ship; Patrol Vessel; Pipe Layer; Platform; Pollution Control 

Vessel; Pontoon; Stone Carrier; Trans Shipment Vessel; Water Tanker; Well 

Stimulation Vessel; Work/Repair Vessel

0 litres/day

1Note that vessels such as barge carriers and inland waterway (IWW) oil tankers may be consuming 

larger amounts of stern tube lubricants due to the degree to which the vessels are submerged.
In the analyses in this report, the value of 6 litres per day is applied as an 

average upper limit and 2.6 litres per day is applied as an average rate. Note that 

there are a number of vessel types for which no stern tube lubricant consumption is 

reported in this data. This may be a matter of not having samples from these 

categories, or in some cases there may actually be no leakage.

2.2 Operational Inputs of Deck Machinery

In addition to spills and stern tube leakage, there are “operational inputs” of 

lubricant oils that occur due to continuous low-level discharges and leakages that 

occur during normal vessel operations in port. The sources of operational discharges 

include deck machinery and in-water (submerged) machinery.

Estimates of operational discharges from these operations in this study are 

based on the “consumption” of oil reported to a lubricant supplier in a five-year 

collection of data on daily usage of lubricating oils while in port and underway. No 

other comparable vessel type- and machinery-specific data were available.

Data were adjusted by removing out-lying values that greatly exceeded 

average values for each vessel and machinery type on the assumption that these 

would rightly be spills rather than routine operational discharges. These data would 

tend to underestimate inputs because the voluntary reporting implies that there is a 

bias towards the more conscientious operators. The assumption is that the oil replaced 

daily during the port visit represents the amount of leakage in the port. Leakage at sea 

is not included herein since that oil would have been replaced during the voyage.

Average per-port visit inputs from deck machinery across all vessel types are 

shown in Table 2. The oil that is used on deck-based machinery can enter the water 

through rain runoff or during deck washing activities. 

Table 2. Average Input of Lubricants from Deck-Based Machinery in Port 

Deck Machinery Type Average Input per Port Visit (litres)

Deck crane gears 0.073

Dredge pump shaft bearings 0.033

Gear-driven mooring winches 0.102

Gear-driven windlasses 0.024

Hose-handling cranes 0.007

Hydraulic system prov cranes 0.022

Hydraulic deck machinery 0.197

Hydraulic windlass mooring winches 0.019

Hydraulic capstans 0.030

Hydraulic cranes 0.096

Hydraulic hatch systems 0.126

Hydraulic mooring winches 0.110

Hydraulic split systems 0.007

Hydraulic system stern ramps 0.027

Miscellaneous hydraulic systems 0.210

Ro-ro hydraulic systems 0.007
Table 2. Average Input of Lubricants from Deck-Based Machinery in Port 

Deck Machinery Type Average Input per Port Visit (litres)

Hydraulic water-tight doors 0.004

Hydraulic windlasses 0.095

Towing winches 0.005

Towing winch gears 0.003

Hydraulic trim tabs 0.025

Tugger winches 0.010

TOTAL 1.232

Again, inputs vary by vessel type. Note that not all vessel types have the machinery 

listed and will thus not have all discharge types listed. Average inputs of lubricating oil from 

deck-based machinery by vessel type are shown in Table 3. It is estimated that about 10% of 

the oil enters the water through runoff or washoff. The rest would adhere to the deck and 

equipment. This may well be an underestimate of input into the water.

Table 3. On-Deck Machinery: Lubricant Consumption per Vessel Port Visit

Vessel Type Average Consumption per Port Visit (litres)

Bulk Carrier 57.92

Container Ship 57.70

General Cargo 52.14

Chemical Tanker 51.00

Cement Carrier 42.38

Passenger/Ro-Ro 39.96

Ro-Ro Cargo Ship 36.90

Self Disch. Bulk 30.47

Crude Oil Tanker 30.18

Pontoon 25.00

ChemicalTanker 24.79

Dredger 23.60

Refrig. Cargo 21.03

Oil Prod.Tanker 20.12

Tug 20.00

Ore Carrier 19.00

Offshore Tug 13.40

Passenger /Cruise 12.50

Motor Hopper 12.33

Heavy Load Carr. 11.67

Fishing Vessel 11.50

Crane Ship 11.00

Container Ro-Ro 10.87

Vehicles Carrier 10.17

Trans Shipment 9.50

Wood Chip Carr. 9.50

Offshore Supply 8.56

Bulk/Oil Carrier 7.00

Dredger 7.00

Palletised Cargo 7.00

Research Vessel 6.67

Live Fish Carrier 6.00

Passenger/ Cargo 5.25

LPG Tanker 5.05
Table 3. On-Deck Machinery: Lubricant Consumption per Vessel Port Visit

Vessel Type Average Consumption per Port Visit (litres)

Trawler 3.67

Fishery Support 3.18

Buoy/Lighthouse 3.00

Standby Safety 3.00

Offshore Support 2.50

Platform 1.30

LNG Tanker 1.00

Patrol Vessel 1.00

Pipe Layer 1.00

2.3 Operational Inputs from Submerged Machinery

In addition to inputs from machinery on vessel decks, there are also more 

direct inputs from in-water (submerged) machinery. There are a number of systems 

situated below the waterline which require to be lubricated. The main ones to 

consider are the stern tube bearing, thruster gearboxes, and horizontal stabilisers. All 

of these have pressurised lubricating oil systems where the pressure is maintained at a 

higher pressure than the surrounding sea. The reason for this is to ensure that no 

significant amount of water enters the oil system, where it would compromise the 

reliability of the unit. The corollary is that any leakage which does take place is from 

the unit outwards into the sea. When the elastomer seals on propeller shafts or 

thruster bearings are in good condition this is a small (but continuous) amount of 

leakage, but any seal wear or damage increases the amount. The lubricant is released 

well below the waterline into an area of turbulence (the propeller) which means that it 

is immediately dispersed and no giveaway sheen occurs on the water surface.

Average inputs of lubricant oils from these in-water machinery sources shown 

in Table 4, and are detailed by vessel type in Table 5. It is assumed that all oil that 

leaks or discharges from these sources enters the water. Note that not all vessel types 

have the machinery listed and will thus not have all discharge types listed.

Table 4. Average Port Visit Input of Lubricants from Submerged Machinery 

Submerged Machinery Type Average Input per Port Visit (litres)

Aquamaster – Gears 0.12

Bow Thruster 1.10

Bow Thruster Gears 0.85

CPP System Gears 0.67

Fin Stabiliser Gear 0.13

Gears - Azimuth Thrusters 0.70

Hydraulic Fin Stabiliser 0.24

Hydraulic Thrusters/ CPP 1.14

Hydraulics - Azimuth Thrusters 0.13

Steering Thrusters 0.04

Stern Thruster 2.39

Stern Thruster Gears 0.21
Table 4. Average Port Visit Input of Lubricants from Submerged Machinery 

Submerged Machinery Type Average Input per Port Visit (litres)

Thruster Gears 0.77

Under Water Pump Shaft Bearing 0.03

Waterjet – Hydraulic 0.03

Waterjet Gears 0.03

TOTAL 8.58

Table 5. In-Water Machinery: Estimated Lubricant Consumption per Port Visit

Vessel Type Average Consumption per Port Visit (litres)

Ro-Ro Cargo Ship 28.77

Passenger/Ro-Ro 27.03

General Cargo 26.28

Offshore Tug 25.68

Palletised Cargo 23.00

Barge Carrier 20.00

Offshore Supply 19.09

Oil Prod.Tanker 18.03

Offshore Support 17.08

Passenger /Cruise 17.01

Motor Hopper 17.00

Vehicles Carrier 16.71

Research Vessel 15.39

LPG Tanker 14.74

Tug 13.58

Crane Ship 13.30

Chemical Tanker 12.00

Container Ship 11.92

IWW Oil Tanker 10.50

Naval 10.00

Pollution Control 10.00

Crude Oil Tanker 8.70

Bulk Carrier 7.79

Cement Carrier 7.42

Standby Safety 6.76

Refrig. Cargo 6.63

Self Disch. Bulk 6.51

Trawler 6.50

Dredger 6.33

Patrol Vessel 6.00

Livestock Carrier 5.67

Sail Training Ship 5.60

Heavy Load Carr. 5.00

Tender 5.00

Water Tanker 5.00

Pusher Tug 4.75

Container Ro-Ro 4.50

Offshore Process 4.11

Pipe Layer 4.00

Well Stimulation 4.00

Passenger Ferry 3.33

Stone Carrier 3.33

Fishing Vessel 3.00
Table 5. In-Water Machinery: Estimated Lubricant Consumption per Port Visit

Vessel Type Average Consumption per Port Visit (litres)

Wood Chip Carr. 2.75

Fishery Support 2.50

Buoy/Lighthouse 2.00

Cable Layer 2.00

Fish Carrier 2.00

Asphalt Tanker 1.50

Work/Repair 1.25

Bulk/Oil Carrier 1.00

LNG Tanker 1.00

For deck machinery-sourced discharges, bulk carriers, and container ships had 

the highest inputs. Hydraulic deck machinery was the largest source of lubricating oil 

discharge. For in-water machinery-sourced discharges, ro-ro cargo, ro-ro 

passenger/cargo, and general cargo ships had the highest input rates. Stern thrusters 

were the largest input source across all vessel types.

2.4 Estimating Discharge Volumes in Port and Harbour Areas

Discharge volumes were developed based on the types of vessels and 

lubricant application types (e.g., stern tube vs. gear) based on five years of data of inport lubricant replacement rates from a lubricant supplier. These rates of discharge 

were then applied on the basis of five years of reported vessel visits by port for all 

4,708 ports worldwide. Stern tube leakage was considered separately from the other 

types of operational discharges.

3 Results

Table 6 shows lubricant operational discharges for top ten ports and Table 7 shows 

lubricant inputs for all nations, assuming maximized stern tube leakage rates.

Table 6. Annual Lubricant Input – Top Ten Ports

Country/Territory Port

Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

Singapore Singapore 892,234 823,657 1,715,891

Turkey Istanbul 787,990 912,282 1,700,272

Gibraltar Gibraltar 668,309 626,562 1,294,871

Germany Brunsbuttel 480,679 604,036 1,084,715

Netherlands Rotterdam 482,222 562,660 1,044,882

China Hong Kong 509,250 520,885 1,030,135

Korea, Republic of Busan 389,508 410,161 799,669

Belgium Antwerp 263,186 286,689 549,875

China Shanghai 269,707 272,884 542,591

Taiwan Kaohsiung 253,375 241,438 494,813
Table 7. Estimated Annual Lubricant Port Inputs – by Nation

Country/Territory

Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

Aland 4,186 7,576 11,762

Albania 35,198 55,982 91,180

Algeria 154,453 182,697 337,150

American Samoa 1,891 2,524 4,415

Angola 22,838 36,007 58,845

Antarctica 29 42 71

Antigua and Barbuda 24 34 58

Argentina 118,319 96,599 214,918

Aruba 1,054 991 2,045

Australia 424,549 374,357 798,906

Azerbaijan 96 132 228

Azores 22,906 24,613 47,519

Bahamas 54,652 78,662 133,314

Bahrain 386 335 721

Bangladesh 32,719 33,287 66,006

Barbados 17 18 35

Belgium 494,290 636,438 1,130,728

Belize 7,532 12,476 20,008

Benin 15,816 14,833 30,649

Bermuda 17 13 30

Brazil 509,298 434,230 943,528

British Indian Ocean Territory 95 85 180

Brunei Darussalam 11,870 10,160 22,030

Bulgaria 73,118 87,926 161,044

Cambodia 7,783 7,900 15,683

Cameroon 16,813 17,292 34,105

Canada 251,926 223,916 475,842

Canary Islands 153,127 178,295 331,422

Cape Verde 26,111 37,949 64,060

Cayman Islands 565 439 1,004

Chile 157,739 151,233 308,972

China 1,834,020 1,835,829 3,669,849

Colombia 178,806 145,476 324,282

Comoros 638 811 1,449

Congo 14,539 18,111 32,650

Congo, The DRC 8,341 8,998 17,339

Cook Islands 156 227 383

Costa Rica 37,422 37,190 74,612

Cote D'ivoire 42,318 44,750 87,068

Croatia 60,342 77,028 137,370

Cuba 9,112 8,831 17,943

Cyprus 82,796 116,790 199,586

Czech Republic 65 44 109

Denmark 284,814 371,981 656,795

Djibouti 14,534 15,121 29,655

Dominica 70 83 153

Dominican Republic 47,436 59,467 106,903

East Timor 1,310 1,961 3,271

Ecuador 51,594 40,976 92,570

Egypt 510,736 495,591 1,006,327
Table 7. Estimated Annual Lubricant Port Inputs – by Nation

Country/Territory

Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

El Salvador 11,158 9,759 20,917

Equatorial Guinea 2,213 2,378 4,591

Eritrea 1,742 2,291 4,033

Estonia 88,001 118,653 206,654

Falkland Islands (Malvinas) 4,928 5,253 10,181

Faroe Islands 7,120 9,769 16,889

Fiji 10,196 12,406 22,602

Finland 344,712 502,486 847,198

France 580,966 757,001 1,337,967

French Guiana 3,522 4,185 7,707

French Polynesia 14,051 21,913 35,964

French Southern Territories 8 10 18

Gabon 11,832 12,227 24,059

Gambia 2,046 2,084 4,130

Georgia 32,152 38,241 70,393

Germany 1,135,122 1,387,392 2,522,514

Ghana 30,413 29,308 59,721

Gibraltar 668,309 626,562 1,294,871

Greece 367,896 485,192 853,088

Greenland 1,810 1,964 3,774

Grenada 378 603 981

Guadeloupe 30,595 48,007 78,602

Guatemala 49,272 54,896 104,168

Guinea 9,656 7,702 17,358

Guinea-Bissau 2,279 2,499 4,778

Guyana 11,788 13,775 25,563

Haiti 12,857 16,465 29,322

Honduras 28,242 36,221 64,463

Hungary 2 1 3

Iceland 17,369 19,320 36,689

India 408,114 375,972 784,086

Indonesia 733,633 753,551 1,487,184

Iran (Islamic Republic Of) 72,899 68,931 141,830

Iraq 17,958 23,662 41,620

Ireland 132,384 177,075 309,459

Isle Of Man 5,377 7,396 12,773

Israel 84,558 96,821 181,379

Italy 1,080,499 1,557,218 2,637,717

Jamaica 38,723 44,550 83,273

Japan 1,824,700 1,855,642 3,680,342

Jordan 22,309 22,819 45,128

Kazakhstan 22 33 55

Kenya 20,990 22,591 43,581

Kiribati 187 261 448

Korea, D.P.R.O. 7,348 7,107 14,455

Korea, Republic Of 1,112,074 1,172,092 2,284,166

Kuwait 25,861 22,568 48,429

Latvia 131,831 168,687 300,518

Lebanon 47,954 57,507 105,461

Liberia 4,127 5,042 9,169

Libyan Arab Jamahiriya 34,616 37,299 71,915
Table 7. Estimated Annual Lubricant Port Inputs – by Nation

Country/Territory

Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

Lithuania 77,201 102,097 179,298

Madagascar 12,901 15,010 27,911

Madeira 10,772 15,573 26,345

Malaysia 536,675 547,924 1,084,599

Maldives 7,466 9,696 17,162

Malta 98,122 123,804 221,926

Marshall Islands 137 117 254

Martinique 14,645 18,309 32,954

Mauritania 13,688 11,426 25,114

Mauritius 17 14 31

Mayotte 3,323 3,998 7,321

Mexico 189,832 225,750 415,582

Micronesia 408 289 697

Monaco 150 409 559

Montenegro 18,733 24,662 43,395

Morocco 119,592 152,774 272,366

Mozambique 20,807 21,612 42,419

Myanmar (Burma) 9,448 11,892 21,340

Namibia 8,851 9,084 17,935

Netherlands 827,455 1,049,775 1,877,230

Netherlands Antilles 21,868 30,888 52,756

New Caledonia 54 79 133

New Zealand 116,974 116,383 233,357

Nicaragua 5,975 5,348 11,323

Nigeria 61,126 53,779 114,905

Northern Mariana Islands 3,929 4,647 8,576

Norway 714,445 942,344 1,656,789

Oman 58,944 55,228 114,172

Pakistan 48,077 45,333 93,410

Palau 229 350 579

Panama 81,568 83,163 164,731

Papua New Guinea 21,979 25,608 47,587

Paraguay 908 1,245 2,153

Peru 47,326 43,344 90,670

Philippines 105,962 107,189 213,151

Poland 167,298 216,423 383,721

Portugal 165,542 189,983 355,525

Puerto Rico 41,191 59,844 101,035

Qatar 41,987 42,295 84,282

Romania 127,752 151,048 278,800

Russian Federation 667,721 781,387 1,449,108

Saint Kitts and Nevis 1,507 2,307 3,814

Saint Lucia 13,658 18,912 32,570

Saint Vincent/Grenadines 493 838 1,331

Samoa 2,734 3,542 6,276

Sao Tome and Principe 1,668 1,952 3,620

Saudi Arabia 174,690 172,616 347,306

Senegal 24,563 25,628 50,191

Serbia 96 101 197

Seychelles 52 57 109

Sierra Leone 4,499 4,776 9,275
Table 7. Estimated Annual Lubricant Port Inputs – by Nation

Country/Territory

Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

Singapore 919,848 848,012 1,767,860

Slovakia (Slovak Republic) 202 285 487

Slovenia 33,166 36,201 69,367

Solomon Islands 4,565 4,808 9,373

Somalia 4,613 6,004 10,617

South Africa 160,756 138,898 299,654

Spain 1,091,378 1,428,806 2,520,184

Sri Lanka 74,076 74,795 148,871

St. Helena 191 256 447

St. Pierre And Miquelon 5 10 15

Sudan 18,420 22,807 41,227

Suriname 3,532 3,453 6,985

Svalbard /Jan Mayen Islands 251 344 595

Sweden 463,799 614,482 1,078,281

Syrian Arab Republic 65,014 78,618 143,632

Taiwan 574,504 558,668 1,133,172

Tanzania 38,870 21,372 60,242

Thailand 180,980 178,151 359,131

Togo 16,768 16,324 33,092

Tonga 2,281 2,997 5,278

Trinidad and Tobago 67,478 71,294 138,772

Tunisia 70,656 104,032 174,688

Turkey 1,322,634 1,570,781 2,893,415

Turkmenistan 295 275 570

Turks and Caicos Islands 491 795 1,286

Tuvalu 102 135 237

U.S. Minor Islands 7 9 16

Uganda 2 6 8

Ukraine 212,476 241,303 453,779

United Arab Emirates 312,184 322,042 634,226

United Kingdom 1,443,647 1,967,101 3,410,748

United States 1,400,726 1,363,235 2,763,961

Uruguay 21,302 18,181 39,483

Vanuatu 2,645 3,546 6,191

Venezuela 146,660 140,010 286,670

Viet Nam 75,077 80,908 155,985

Virgin Islands (British) 8,008 15,352 23,360

Virgin Islands (U.S.) 42,018 72,851 114,869

Wallis/ Futuna Islands 4 3 7

Western Sahara 6,031 6,730 12,761

Yemen 47,340 47,153 94,493

TOTAL 28,593,300 32,283,580 60,876,880

Table 8. Estimated Annual Lubricant Port Inputs – Top Ten Nations

Country/Territory

Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

Japan 1,824,700 1,855,642 3,680,342

China 1,834,020 1,835,829 3,669,849

United Kingdom 1,443,647 1,967,101 3,410,748

Turkey 1,322,634 1,570,781 2,893,415
Country/Territory Annual Lube Oil Inputs in Ports (litres)

Stern Tube Other Operational Total 

United States 1,400,726 1,363,235 2,763,961

Italy 1,080,499 1,557,218 2,637,717

Germany 1,135,122 1,387,392 2,522,514

Spain 1,091,378 1,428,806 2,520,184

Korea, Republic Of 1,112,074 1,172,092 2,284,166

Netherlands 827,455 1,049,775 1,877,230

The results indicate that each year in over 1.7 million vessel port visits, an 

estimated 4.6 million to as much as 28.6 million litres of lubricating oil leaks from 

stern tubes and 32.3 million litres of oil is input to marine waters from other 

operational discharges and leaks. In total, operational discharges (including stern tube 

leakage) inputs at least 32.3 million litres to as much as nearly 61 million litres of 

lubricating oil into marine port waters annually – the equivalent of about one and a 

half Exxon Valdez-sized spills.

If the same rates of discharge occur at sea as they do in port, the estimated 

worldwide annual inputs of lubricants to marine waters both in ports and harbours 

and at sea might be estimated to be about four times the port estimate. This assumes 

that each vessel spends, on average, three days at sea for every day in port. Total 

worldwide of lubricants from operational leaks and discharges would then be about 

130 million to 244 million litres annually. The results are broken down by vessel type 

as shown in Table 9. These values are the estimated amount of lubricant discharge in 

ports based on the average annual number of port visits for each vessel type.

Table 9. Worldwide Lube Leakage in Port by Vessel Type 2004 – 2008

Vessel Type Annual 

Port Visits

Operational Leakage Rate (Litres/Port Visit) Total Per 

Year 

(litres)

Stern 

Tube

Deck 

Machinery *

In-Water 

Machinery**

Total 

Discharge

General Cargo 481,819 18.00 5.21 20.28 43.49 20,954,453

Container Ship 356,992 18.00 5.77 10.46 34.23 12,218,944

Prod Tanker 197,501 18.00 2.01 15.04 35.05 6,923,200

Ro-Ro Cargo 172,566 12.00 3.69 24.67 40.36 6,964,419

Bulk Carrier 143,765 18.00 5.79 1.93 25.73 3,698,383

Crude Tanker 55,665 18.00 3.02 11.00 32.02 1,782,299

Vehicle Carrier 49,754 18.00 1.02 17.05 36.07 1,794,463

Passenger Ship 42,285 6.00 1.25 15.04 22.29 942,617

LPG Tanker 37,625 12.00 0.51 12.18 24.69 928,863

Chem Tanker 35,682 18.00 5.10 8.50 31.60 1,127,551

Refrig Cargo 30,501 12.00 2.10 3.00 17.10 521,653

Tug 19,786 6.00 2.00 10.39 18.39 363,884

Offshore Supply 18,671 6.00 0.86 23.21 30.07 561,411

Cement Carrier 15,341 12.00 4.24 5.71 21.95 336,767

Self-Discharge 11,932 18.00 3.05 5.33 26.38 314,763

Fishing Vessel 11,833 6.00 1.15 2.00 9.15 108,272

Passenger Ferry 9,120 18.00 0.00 2.00 20.00 182,400

LNG Tanker 6,809 18.00 0.10 0.00 18.10 123,243

Hopper Dredger 4,939 12.00 2.36 3.33 17.69 87,386
Table 9. Worldwide Lube Leakage in Port by Vessel Type 2004 – 2008

Vessel Type Annual 

Port Visits

Operational Leakage Rate (Litres/Port Visit) Total Per 

Year 

(litres)

Stern 

Tube

Deck 

Machinery *

In-Water 

Machinery**

Total 

Discharge

Palletized Cargo 4,928 12.00 0.70 20.00 32.70 161,146

Pusher Tug 4,321 6.00 0.00 1.50 7.50 32,408

Dredger 4,124 6.00 0.70 0.00 6.70 27,631

Bitumen Tanker 3,843 12.00 0.00 0.00 12.00 46,116

Research Vessel 3,787 6.00 0.67 12.67 19.33 73,216

Not Specified 3,608 0.00 0.00 0.00 0.00 0

Fish Factory 3,276 12.00 0.60 0.00 12.60 41,278

Barge 3,221 6.00 0.00 0.00 6.00 19,326

Landing Craft 3,072 0.00 0.70 0.00 0.70 2,150

Wood Chips 2,674 18.00 0.95 0.00 18.95 50,672

Heavy Load 2,422 18.00 1.17 11.00 30.17 73,064

Livestock Carr 2,205 18.00 0.00 1.00 19.00 41,895

Edible Oil Tank 2,182 6.00 2.48 8.68 17.16 37,436

Ore Carrier 1,796 18.00 1.90 0.00 19.90 35,740

Standby Vessel 1,466 0.00 0.30 5.90 6.20 9,089

Deck Cargo 1,351 12.00 1.09 2.00 15.09 20,382

Yacht 1,290 0.00 0.00 0.00 0.00 0

Pontoon 1,159 6.00 2.50 0.00 8.50 9,852

Wine Tanker 892 6.00 2.48 8.68 17.16 15,304

Motor Hopper 880 6.00 1.23 17.00 24.23 21,325

Cable Layer 800 6.00 0.00 2.00 8.00 6,400

Limestone Carr 758 18.00 0.00 0.00 18.00 13,644

Naval 753 12.00 0.00 0.00 12.00 9,036

Crewboat 737 0.00 0.00 0.00 0.00 0

Buoy Vessel 673 0.00 0.30 2.00 2.30 1,548

Stone Carrier 571 18.00 0.00 3.33 21.33 12,181

Patrol Vessel 552 0.00 0.10 6.00 6.10 3,367

Other Ships 474 6.00 0.00 0.00 6.00 2,844

Training Ship 467 0.00 0.00 3.60 3.60 1,681

Water Tanker 458 6.00 0.00 5.00 11.00 5,038

Training Ship 430 6.00 0.00 3.60 9.60 4,128

Utility Vessel 426 0.00 0.70 0.00 0.70 298

Offshore Proc 412 18.00 0.00 4.11 22.11 9,108

Ore/Oil Carrier 390 18.00 0.70 0.00 18.70 7,293

Waste Vessel 362 6.00 0.00 1.25 7.25 2,625

Urea Carrier 327 18.00 2.48 8.68 29.16 9,534

Fishing Support 306 6.00 0.32 2.50 8.82 2,698

Pollution Control 300 6.00 0.00 10.00 16.00 4,800

Supply Vessel 254 6.00 1.34 27.53 34.87 8,856

Aggreg Carrier 253 6.00 0.00 0.00 6.00 1,518

Juice Tanker 251 18.00 2.48 8.68 29.16 7,318

Salvage Ship 218 0.00 0.70 0.00 0.70 153

Pipe Layer 213 18.00 0.10 7.00 25.10 5,346

Platform 191 12.00 0.13 0.00 12.13 2,317

Work Vessel 175 0.00 0.00 1.25 1.25 219

Well Vessel 141 12.00 0.00 33.36 45.36 6,396

Sludge Tanker 130 18.00 2.48 8.68 29.16 3,790

Icebreaker 122 12.00 0.70 0.00 12.70 1,549

Crane Ship 100 0.00 1.10 13.30 14.40 1,440

Sugar Carrier 81 18.00 2.48 8.68 29.16 2,362

Search/ Rescue 79 0.00 0.70 0.00 0.70 55
Table 9. Worldwide Lube Leakage in Port by Vessel Type 2004 – 2008

Vessel Type Annual 

Port Visits

Operational Leakage Rate (Litres/Port Visit) Total Per 

Year 

(litres)

Stern 

Tube

Deck 

Machinery *

In-Water 

Machinery**

Total 

Discharge

Drilling Ship 75 18.00 1.34 27.53 46.87 3,515

Pilot Vessel 60 0.00 0.70 0.00 0.70 42

Mooring Vessel 53 0.00 0.70 0.00 0.70 37

Powder Carrier 50 6.00 0.00 0.00 6.00 300

Alum Carrier 45 18.00 0.00 0.00 18.00 810

Seal Catcher 37 0.00 0.37 4.00 4.37 162

Molasses Tank 29 6.00 2.48 8.68 17.16 498

Tender 27 6.00 0.00 0.00 6.00 162

Nuclear Carrier 25 18.00 0.00 0.00 18.00 450

Hospital Vessel 24 12.00 0.00 0.00 12.00 288

Fish Oil Tanker 23 6.00 2.48 8.68 17.16 395

Tank-Cleaning 20 6.00 0.00 1.25 7.25 145

Production Test 17 12.00 0.25 23.79 36.04 613

Fire Fighting 16 6.00 0.70 0.00 6.70 107

Trans-Shipment 9 18.00 0.95 0.00 18.95 171

Whale Catcher 4 6.00 0.37 4.00 10.37 41

Air Cushion 1 0.00 0.00 0.00 0.00 0

Anchor Hoy 1 0.00 0.00 0.00 0.00 0

Floating Dock 1 0.00 0.00 0.00 0.00 0

Launch 1 0.00 0.70 0.00 0.70 1

Tug 1 6.00 0.00 1.50 7.50 8

TOTAL 1,767,006 --- --- --- --- 60,798,285

*Assumes 10% oil on deck washes into water through deck sweeping, rinsing, or rain runoff; Includes: 

deck crane gears, dredge pump shaft bearings, gear-driven mooring winches, gear-driven windlasses, 

hose-handling cranes, hydraulic system prov cranes, hydraulic deck machinery, hydraulic windlass 

mooring winches, hydraulic capstans, hydraulic cranes, hydraulic hatch systems, hydraulic mooring 

winches, hydraulic split systems, hydraulic system stern ramps, miscellaneous hydraulic systems, ro-ro 

hydraulic systems, hydraulic water-tight doors, hydraulic windlasses, towing winches, towing winch 

gears, hydraulic trim tabs, and tugger winches.

** Includes: aquamaster gears, bow thrusters, bow thruster gears, CPP system gears, fin stabilizer 

gears, azimuth thruster gears, hydraulic fin stabilizers, hydraulic CPP thrusters, hydraulic azimuth 

thrusters, steering thrusters, stern thrusters, stern thruster gears, underwater pump shaft bearings, 

hydraulic waterjets, and waterjet gears.

3.3 Lubricant Spill Impacts and Cost Damages

Oil pollution impacts from lubricating oils need to be viewed in respect of the 

properties of the lubricating oils (physical behavior, toxicity, etc.), the volumes 

involved (large numbers of relatively small-volume inputs), and locations involved.

The impacts of spills of lubricant oils in ports involve a combination of the 

costs involved in cleaning up the spilled oil, the socio-economic impacts (port 

closures during cleanup response operations, precautionary water intake closures, 

fishing impacts, tourism impacts), and environmental damages. Because different oil 

types vary in their impacts and present different challenges for detection and response 

due their chemical and physical properties (viscosity, specific gravity, evaporation 

rate, etc.), they need to be considered separately in any evaluation of spill impacts.

Likewise, different oil types exhibit different degrees of toxicity, propensity of 

adherence to bird feathers and mammal hairs and fur, different residence time in the 
environment, and different potentials for bioaccumulation, environmental impacts can 

vary considerably by oil type.

Because conventional mineral-based lubricant oils differ significantly in their 

properties and hence their impacts from crude oils and many petroleum products 

(e.g., diesel fuel, heavy fuel oil), the spills of these oils should be evaluated and 

estimated in that regard. Spills of lubricating oils do not readily evaporate but do 

physically disperse into the water column and remain in the environment for some 

time. The environmental impact of lubricating oils is not insignificant (VazquezDuhalt, 1989) due to their persistence and the frequent presence of heavy-metal 

additives that increase their toxicity. 

This study estimated the costs and damages associated with the stern tube 

leakage, and other operational discharges estimated to have occurred worldwide 

using ERC’s Basic Oil Spill Cost Estimation Model (BOSCEM) (Etkin, 2004) and 

relevant portions of the Oil Spill Response Cost- Effectiveness Analytical Tool 

(OSRCEAT) (Etkin, 2005), as well as an evaluation of the behavior of these oils in 

previous spill modeling studies and known characteristics of these oils.

Spills of lubricant oils involve response costs as well as socio-economic and 

environmental damage costs, but chronic low-volume operational discharges of 

lubricants are unlikely to result in the types of responses generally applied in spills. 

For this reason, for the operational discharges and leaks estimated in this study only 

environmental damage costs are estimated. Socio-economic damages are not included 

because it would be highly unlikely that there would be claims of damages to 

resources upon which livelihoods are based, mainly because there would be no 

general awareness of these operational inputs by potential claimants.

Note that the “environmental damage” costs are estimated based on natural 

resource damage assessment (NRDA) habitat equivalency analysis methodologies 

used in the US. These methods involve estimating the costs of rehabilitating, 

restoring, or recreating the impacted environment. While currently there are no 

known applications of actual environmental damage assessments outside the US, 

there is a move to include these types of damage costs in the European Union (based 

on the EU Environmental Liability Directive). Also, within the IMO Marine 

Environmental Protection Committee, a working group is addressing the issue of 

valuation of averted oil spillage with regard to averted environmental damage costs. 

The actual application of these types of environmental damage costs are unclear at 

this time, though many experts believe that a methodology similar to the habitat 

equivalency analysis used in the US will be applied. Note that at this time, however, 

responsible parties in spills are generally not required to pay these types of damages. 

In the context of this study, the environmental damage figures are a way to quantify 

environmental impacts using the best methodologies currently available.

Estimated annual environmental damages from lubricant discharges in ports 

are shown in Table 10 for the ten nations with the highest damages and in Table 11 

for all nations. Per-unit costs were developed for each nation by adjusting the per-unit 
costs in ERC’s Basic Oil Spill Cost Estimation Model (BOSCEM) and relevant 

portions of ERC’s Oil Spill Response Cost Effectiveness Analytical Tool 

(OSRCEAT) as adjusted by regional and national factors (as in Etkin, 2000) adjusted 

to 2010 US dollars.

Table 10. Estimated Damage Costs from Lubricant Inputs – Top Ten Nations

Country Operational Discharges/Stern Tube Leakage 

(litres)

Total Annual Cost 

(US$)

Japan 3,680,342 $47,539,066 

China 3,669,849 $47,403,528 

United States 2,763,961 $30,985,573 

Korea, Rep. of 2,284,166 $29,504,627 

Singapore 1,767,860 $22,835,490 

Indonesia 1,487,184 $19,209,992 

Taiwan 1,133,172 $14,637,210 

Malaysia 1,084,599 $14,009,791 

India 784,086 $10,128,058 

United Kingdom 3,410,748 $6,803,072 

Table 11. Estimated Damage Costs from Lubricant Inputs by Country 

Country/Territory

Operational 

Discharges and 

Stern Tube Leakage 

(litres)

Per Litre 

Environmental Damage 

Cost (US $)

Total Annual Cost 

(US$)

Aland 11,762 $1.99 $23,460

Albania 91,180 $1.99 $181,867

Algeria 337,150 $0.17 $57,528

American Samoa 4,415 $11.21 $49,495

Angola 58,845 $0.17 $10,041

Antarctica 71 $1.99 $142

Antigua/Barbuda 58 $0.16 $9

Argentina 214,918 $0.16 $34,384

Aruba 2,045 $0.16 $327

Australia 798,906 $1.99 $1,593,497

Azerbaijan 228 $1.99 $455

Azores 47,519 $1.99 $94,781

Bahamas 133,314 $1.99 $265,908

Bahrain 721 $0.02 $14

Bangladesh 66,006 $12.92 $852,601

Barbados 35 $0.16 $6

Belgium 1,130,728 $1.99 $2,255,348

Belize 20,008 $0.16 $3,201

Benin 30,649 $0.16 $4,903

Bermuda 30 $1.99 $60

Brazil 943,528 $0.16 $150,951

Brit. Ind. O. Terr. 180 $1.99 $359

Brunei Darussalam 22,030 $0.17 $3,759

Bulgaria 161,044 $1.99 $321,218

Cambodia 15,683 $12.92 $202,578

Cameroon 34,105 $0.17 $5,819

Canada 475,842 $0.72 $344,502

Canary Islands 331,422 $1.99 $661,054

Cape Verde 64,060 $0.17 $10,931
Table 11. Estimated Damage Costs from Lubricant Inputs by Country 

Country/Territory

Operational 

Discharges and 

Stern Tube Leakage 

(litres)

Per Litre 

Environmental Damage 

Cost (US $)

Total Annual Cost 

(US$)

Cayman Islands 1,004 $0.16 $161

Chile 308,972 $0.16 $49,431

China 3,669,849 $12.92 $47,403,528

Colombia 324,282 $0.16 $51,881

Comoros 1,449 $0.17 $247

Congo 32,650 $0.17 $5,571

Congo, The DRC 17,339 $0.17 $2,959

Cook Islands 383 $1.99 $764

Costa Rica 74,612 $0.16 $11,937

Cote D'ivoire 87,068 $0.17 $14,856

Croatia 137,370 $1.99 $273,998

Cuba 17,943 $0.16 $2,871

Cyprus 199,586 $1.99 $398,094

Czech Republic 109 $1.99 $217

Denmark 656,795 $1.99 $1,310,042

Djibouti 29,655 $0.17 $5,060

Dominica 153 $0.16 $24

Dominican Rep. 106,903 $0.16 $17,103

East Timor 3,271 $12.92 $42,252

Ecuador 92,570 $0.16 $14,810

Egypt 1,006,327 $0.02 $19,213

El Salvador 20,917 $0.16 $3,346

Equatorial Guinea 4,591 $0.17 $783

Eritrea 4,033 $0.17 $688

Estonia 206,654 $1.99 $412,192

Falkland I. (Malv.) 10,181 $0.16 $1,629

Faroe Islands 16,889 $0.16 $2,702

Fiji 22,602 $12.92 $291,951

Finland 847,198 $1.99 $1,689,820

France 1,337,967 $1.99 $2,668,707

French Guiana 7,707 $0.17 $1,315

French Polynesia 35,964 $12.92 $464,548

French South.Terr. 18 $0.16 $3

Gabon 24,059 $0.17 $4,105

Gambia 4,130 $0.17 $705

Georgia 70,393 $1.99 $140,406

Germany 2,522,514 $1.99 $5,031,402

Ghana 59,721 $0.17 $10,190

Gibraltar 1,294,871 $1.99 $2,582,747

Greece 853,088 $1.99 $1,701,568

Greenland 3,774 $1.99 $7,528

Grenada 981 $0.16 $157

Guadeloupe 78,602 $0.16 $12,575

Guatemala 104,168 $0.16 $16,665

Guinea 17,358 $0.17 $2,962

Guinea-Bissau 4,778 $0.17 $815

Guyana 25,563 $0.16 $4,090

Haiti 29,322 $0.16 $4,691

Honduras 64,463 $0.16 $10,313

Hungary 3 $1.99 $6
Table 11. Estimated Damage Costs from Lubricant Inputs by Country 

Country/Territory

Operational 

Discharges and 

Stern Tube Leakage 

(litres)

Per Litre 

Environmental Damage 

Cost (US $)

Total Annual Cost 

(US$)

Iceland 36,689 $1.99 $73,180

India 784,086 $12.92 $10,128,058

Indonesia 1,487,184 $12.92 $19,209,992

Iran 141,830 $0.02 $2,708

Iraq 41,620 $0.02 $795

Ireland 309,459 $1.99 $617,246

Isle Of Man 12,773 $1.99 $25,477

Israel 181,379 $0.02 $3,463

Italy 2,637,717 $1.99 $5,261,186

Jamaica 83,273 $0.16 $13,323

Japan 3,680,342 $12.92 $47,539,066

Jordan 45,128 $0.02 $862

Kazakhstan 55 $1.99 $110

Kenya 43,581 $0.17 $7,436

Kiribati 448 $0.17 $76

Korea, D.P.R.O. 14,455 $12.92 $186,716

Korea, Republic Of 2,284,166 $12.92 $29,504,627

Kuwait 48,429 $0.02 $925

Latvia 300,518 $1.99 $599,413

Lebanon 105,461 $0.02 $2,014

Liberia 9,169 $0.17 $1,565

Libyan Arab Jama. 71,915 $0.17 $12,271

Lithuania 179,298 $1.99 $357,627

Madagascar 27,911 $0.17 $4,762

Madeira 26,345 $1.99 $52,548

Malaysia 1,084,599 $12.92 $14,009,791

Maldives 17,162 $0.17 $2,928

Malta 221,926 $1.99 $442,653

Marshall Islands 254 $0.16 $41

Martinique 32,954 $0.16 $5,272

Mauritania 25,114 $0.17 $4,285

Mauritius 31 $0.17 $5

Mayotte 7,321 $12.92 $94,566

Mexico 415,582 $0.16 $66,487

Micronesia 697 $12.92 $9,003

Monaco 559 $1.99 $1,115

Montenegro 43,395 $1.99 $86,556

Morocco 272,366 $0.17 $46,474

Mozambique 42,419 $0.17 $7,238

Myanmar (Burma) 21,340 $12.92 $275,649

Namibia 17,935 $0.17 $3,060

Netherlands 1,877,230 $1.99 $3,744,320

Neth. Antilles 52,756 $12.92 $681,451

New Caledonia 133 $12.92 $1,718

New Zealand 233,357 $1.99 $465,453

Nicaragua 11,323 $0.16 $1,812

Nigeria 114,905 $0.17 $19,606

N. Mariana I. 8,576 $11.21 $96,142

Norway 1,656,789 $1.99 $3,304,628

Oman 114,172 $0.02 $2,180
Table 11. Estimated Damage Costs from Lubricant Inputs by Country 

Country/Territory

Operational 

Discharges and 

Stern Tube Leakage 

(litres)

Per Litre 

Environmental Damage 

Cost (US $)

Total Annual Cost 

(US$)

Pakistan 93,410 $12.92 $1,206,579

Palau 579 $12.92 $7,479

Panama 164,731 $0.16 $26,355

Papua New Guinea 47,587 $0.17 $8,120

Paraguay 2,153 $0.16 $344

Peru 90,670 $0.16 $14,506

Philippines 213,151 $12.92 $2,753,277

Poland 383,721 $1.99 $765,369

Portugal 355,525 $1.99 $709,130

Puerto Rico 101,035 $11.21 $1,132,660

Qatar 84,282 $0.02 $1,609

Romania 278,800 $1.99 $556,094

Russian Federation 1,449,108 $1.99 $2,890,388

Saint Kitts/ Nevis 3,814 $0.16 $610

Saint Lucia 32,570 $0.16 $5,211

St. Vincent/Gren. 1,331 $0.16 $213

Samoa 6,276 $11.21 $70,358

Sao Tome/Principe 3,620 $0.16 $579

Saudi Arabia 347,306 $0.02 $6,631

Senegal 50,191 $0.17 $8,564

Serbia 197 $1.99 $393

Seychelles 109 $0.17 $19

Sierra Leone 9,275 $0.17 $1,583

Singapore 1,767,860 $12.92 $22,835,490

Slovakia 487 $1.99 $971

Slovenia 69,367 $1.99 $138,359

Solomon Islands 9,373 $12.92 $121,071

Somalia 10,617 $0.17 $1,812

South Africa 299,654 $0.17 $51,130

Spain 2,520,184 $1.99 $5,026,755

Sri Lanka 148,871 $12.92 $1,922,970

St. Helena 447 $1.99 $892

St. Pierre/Miquel. 15 $1.99 $30

Sudan 41,227 $0.17 $7,035

Suriname 6,985 $0.16 $1,118

Svalbard/Jan May. 595 $1.99 $1,187

Sweden 1,078,281 $1.99 $2,150,737

Syrian Arab Rep. 143,632 $0.02 $2,742

Taiwan 1,133,172 $12.92 $14,637,210

Tanzania 60,242 $0.17 $10,279

Thailand 359,131 $12.92 $4,638,904

Togo 33,092 $0.17 $5,646

Tonga 5,278 $0.17 $901

Trinidad/Tobago 138,772 $0.16 $22,202

Tunisia 174,688 $0.17 $29,807

Turkey 2,893,415 $1.99 $5,771,201

Turkmenistan 570 $1.99 $1,137

Turks/Caicos I. 1,286 $12.92 $16,611

Tuvalu 237 $12.92 $3,061

US Minor Islands 16 $11.21 $179
Table 11. Estimated Damage Costs from Lubricant Inputs by Country 

Country/Territory

Operational 

Discharges and 

Stern Tube Leakage 

(litres)

Per Litre 

Environmental Damage 

Cost (US $)

Total Annual Cost 

(US$)

Uganda 8 $0.17 $1

Ukraine 453,779 $1.99 $905,107

United Arab Emir. 634,226 $0.02 $12,109

United Kingdom 3,410,748 $1.99 $6,803,072

United States 2,763,961 $11.21 $30,985,573

Uruguay 39,483 $0.16 $6,317

Vanuatu 6,191 $0.17 $1,056

Venezuela 286,670 $12.92 $3,702,923

Viet Nam 155,985 $12.92 $2,014,862

Virgin I. (UK) 23,360 $1.99 $46,594

Virgin Islands (US) 114,869 $11.21 $1,287,747

Wallis/Futuna Isl. 7 $12.92 $90

Western Sahara 12,761 $0.17 $2,177

Yemen 94,493 $0.02 $1,804

TOTAL 60,876,883 $322,135,640

Total estimated costs for lubricating oil operational leak and discharge 

worldwide based on the probabilities of operational discharges by vessel type in the 

4,708 ports worldwide range are estimated to be US$322 million annually. 

3.4 Future Changes

The estimated damages are based on current shipping rates (i.e., vessel port 

visits) and practices. Future oil inputs, and thus damages, will be determined by 

changes in shipping rates, as well as the implementation of spill and operational 

leakage and discharge prevention measures and practices. 

On the other hand, it is also likely that there may be significant changes in 

practices that will result in reductions in operational oil inputs. The fact that there has 

been more public and industry awareness about operational inputs of lubricating oils 

may lead to more voluntary and regulatory changes in the usage of these lubricants. 

While operational discharges and leakages of lubricating oil as discussed in this 

report were not included in the two most significant international studies of oil inputs 

into the marine environment in recent years (National Research Council, 2003; 

GESAMP, 2007), there is evidence that there has been an increasing trend to 

recognize these inputs as greater than spillage-related inputs in international arenas. 

The issue is being considered by the IMO Marine Environment Protection Committee 

and the European Commission (Pavlakis et al., 2001). The development of Marine 

Protected Areas (MPAs) also may lead to tougher restrictions and more conscientious 

operations in these waters.

In the US, the recent implementation of an Environmental Protection Agency 

(EPA) regulation that requires all commercial and non-recreational vessels of 79 feet 

(24 metres) to have general permits under the National Pollution Discharge 

Elimination System (NPDES) for all operational discharges of any pollutant in US 
waters will include discharges of lubricating oils from stern tubes, deck-based 

machinery, and submerged machinery.

Since a certain proportion of lubricant lost to the sea comes from mechanical 

failure, more regular inspections of equipment by port authorities, in addition to 

modernization of fleets, would also reduce the problem.

There are also a growing number of alternatives to conventional lubricating 

oil usage with the supply of bio-based lubricating oils for vessels designed to meet 

the higher environmental standards for lubricants of the North Sea offshore oil and 

gas industries. Newly-developed non-oil-based bio-lubricants are significantly less 

toxic and 100% more biodegradable than conventional mineral-based lubricating oils, 

but are not yet widely used. There have also been significant advances through 

alternative engineering designs for stern tubes that eliminate or reduce the amount of 

lubricating oil in use, such as seawater-lubricated propeller shaft bearings (e.g., 

Thorndon, 2004; Carter, 2009).

4 Discussion

This study focuses on marine inputs of lubricant oils within the 4,708 ports 

and harbors of the world through spillage, stern tube leakage, and operational 

discharges in marine shipping. Overall, the results indicate that each year in over 1.7 

million vessel port visits, an estimated 4.6 to 28.6 million litres of lubricating oil 

leaks from stern tubes, and 32.3 million litres of oil from other operational discharges 

and leaks. Total annual inputs of lubricating oil worldwide from stern tube leakage

and other operational discharges into port waters is estimated to be between 37

million to nearly 61 million litres.

This analysis focuses on discharges in and near ports and harbours and does 

not specifically estimate the amount of lubricating oil that is discharged in shipping 

lanes and on the open sea during transit. The rate of discharge during transit may, 

however, be inferred from the rate at which vessels discharge while in port. Since 

vessels generally spend more time in transit than in port, the actual level of discharge 

worldwide may be several times what is estimated for ports and harbours. Thus, the 

estimate for ports and harbours represents a very conservative estimate of the global 

lubricant pollution problem.

Assuming that the higher estimate of stern tube leakage is representative of 

the inputs that may occur in port as well as in transit, the total estimated input of 

lubricating oil from leakage and operational discharges represents nearly 61 million 

litres annually worldwide. Putting this volume into perspective with other coastal and 

marine-based sources of oil pollution, this represents about 10% above the total oil 

inputs into marine waters estimated in the 2003 NRC Oil in the Sea study (Figure 1).
Figure 1. Annual Oil Inputs into the Marine Environment (based on NRC, 2003)

Atmospheric deposition from vessel operations and land-based runoff are not 

included in this analysis. Note that the category of vessel operational discharges 

includes MARPOL-permitted discharges at sea but do not include lubricant leakage. 

Lubricant spills are included under tank ship spills and non-tank vessel spills.

Total estimated costs for lubricating oil operational leak and discharge 

worldwide based on the probabilities of operational discharges by vessel type in the 

4,708 ports worldwide range are estimated to be US$322 million annually.

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