Marine engines fuels and lubricants

Real signs of expansion have only been visible since 1988 and it was only in 1989 that the largest figure ever met of more than 3900 million tonnes of products transported by sea was rea

MARINE ENGINES

FUELS AND LUBRICANTS

by Claude OUVRIER-BUFFET

HEAD OF THE MARINE LUBRICANT TECHNICAL DEPARTMENT

SOCIETE DES LUBRIFIANTS ELF AQUITAINE

THE AUTHOR:

Claude OUVRIER-BUFFET qualified as a chemical engineer at Lille ChemistryAcademy (1969) and graduated from the Ecole Nationale Superieure du Petrole

et des Moteurs, Institut Fran9ais du Petrole (1970)

He joined the ELF AQUITAINE GROUP in 1972 as Research and Developmentengineer engaged in the formulation of automotive and industrial lubricants

In 1978, he took over ELF LUB MARINE's Research and Development at the ELFResearch Center

In 1988, he was appointed Head of the Marine Lubricant Technical Department

at the Societe des Lubrifiants Elf Aquitaine in Paris

He is the author of numerous papers on lubricants and lubrication of marineengines published in specialized reviews and in international conferences

He gives a course of lectures on lubrication of marine engines at the EcoleNationale Superieure du Petrole et des Moteurs, France

ACKNOWLEDGEMENTS:

The Author gratefully acknowledges the help and advice given by engine andequipment manufacturers in providing materials and illustrations and checking ofthe subject matter Also to shipowners' technical departments for their helpfulsuggestions

The Author would also like to express thanks to his colleagues and friends fromELF and from LUB MARINE partners all over the world Special thanks must begiven to the Marine department team from the ELF Research Center in LYON(FRANCE)

LUBRICANT STORAGE AND TREATMENT - APPLICATION PROBLEMS 213

INTRODUCTION

Lubricant associated problems encountered on board merchant ships cannot bediscussed without first considering other subjects in the field that do not at firstglance seem to have any direct connection to the subject The technology ofmarine engines and on board equipment is constantly evolving The ships onwhich they are installed are dependent on technological advances, and aresubject to the changing economic requirements of profitability and safety andenvironmental protection which are more and more restraining.

The properties and performance of lubricants are determined by the in-serviceconditions that must not be allowed to affect it Then lubricants must continuallyevolve in order to adapt to new constraints

Good engine operation is essential not only for the ship to complete its task onschedule and under the best possible economic conditions, but also for thesafety of crew and equipment In this context, lubricants and fuels play anessential role

Good engine operation depends on six main parameters:

1 Engine operating conditions linked to trade activity,type of ship andeconomic considerations;

2 Engine and auxiliary machinery maintenance;

3 Fuel quality linked to the world refining industry activities and petroleumproduct consumption;

4 Fuel preparation and treatement;

5 Lubricant quality linked to the type of engine, its operating conditionsand the fuel used;

6 Lubricant purification treatment

Lubrication of all other important equipment on ships has also to be studied andselected on a case by case basis with the same care as for the main engines

It also seems interesting to describe the economical context in which the menwho design, develop and sell "marine" lubricants operate

This will give an overall picture and better understanding of certain requirements

of this particular economic sector that is not always appreciated,but isindispensable to international trade

MAIN TRENDS IN INTERNATIONAL SEABORNE TRADE

GENERAL

DRY BULK SEABORNE TRADE

3250 million tonnes of various products were transported by sea.

Growth between 1964 and 1974 averaged 9% per year A sharp fall caused bythe oil crisis was followed by almost as sharp an upswing The greatest amount

of products ever transported was 3700 million tonnes in 1979 There wasanother recession lasting until 1983, which was in turn followed by a slightrecovery and stabilization Real signs of expansion have only been visible since

1988 and it was only in 1989 that the largest figure ever met of more than

3900 million tonnes of products transported by sea was reached (Fig 1)

After this rapid growth for such a long period of time (1964-1974), adaptation to

a sudden crisis could not be other than difficult As in all sectors, supply anddemand have to be adjusted The tonnage of ships available for the merchantmarine industry is no exception

Movement of crude oil and petroleum products, raw materials, andmanufactured goods depends on the economic health of the countries involvedand are thus influenced by political and economic factors at any given moment

The conditions for growth of imports and exports between countries may beextremely different and variable from one year to the next But a ship cannot bedesigned or built in a few months A 550,000-tonne oil tanker which was ordered

in 1971 and tested at sea in 1975 when the economic crisis was already wellunderway is a prime example of this

To build the appropriate ships, shipowners must not only be able to forecastfuture markets, but also be able to finance these ships

CRUDE OIL AND PETROLEUM PRODUCTS

As a raw material necessary to the growth of modern economies and usuallytransported over large distances, oil has always occupied a predominantposition in international seaborne trade Growth was continuous until 1973,when 1841 million tonnes of oil were transported by sea After a sharp dropfollowed by just as sharp a recovery, another fall occurred until 1983, followed inturn by stabilization at close to 1250 million tonnes A new tendancy toexpansion is really visible since 1988 In 1989,1470 million tonnes of crude oiland petroleum products were transported by sea (Fig 1)

In 1973, oil accounted for as much as 60% of seaborne trade; Although today itsshare is only around 37%, it is still the leading product transported

The tonnage of petroleum products (excluding crude oil) transported has variedlIittle in quantity, but its percentage has increased considerably It rose from15.6% in 1975 to 23.1 % in 1989.Because of the startup of refineries inproducing countries,this tonnage is becoming more and more important sincethese last years (Fig 2).

For political, logistical and geographical reasons, the share of different suppliersfrom a given country may vary from one year to the next Price and exchangerate considerations may also influence this choice

There are no simple solutions, and changes in trade patterns are accompanied

by constant changes in maritime transport The most significant example in thisarea is the size of oil tankers which will be discussed later

The average distance crude oil is shipped has decreased from 7200 miles in themid-70s to some 4700 miles currently

With regard France, this distance has dropped from 9,000 miles in 1976 to lessthan 3,000 miles in 1989

In 1989, the United States was still the world's largest importer of crude oil andpetroleum products (397 Mt), followed by Japan (245 Mt) Western Europeimported 477 Mt, much less than the 1979 figure (675 Mt)

The Soviet Union is one of the few industrialized countries that is independent interms of oil supply In 1989, it exported 20% of its crude oil production and 10%

of its refined product production The U.S.S.R is the world's second-ranked oilexporter, after Saudi Arabia

DRY BULK SEABORNE TRADE

111.1IRON ORE

Iron ore is the predominant dry bulk commodity in world seaborne trade Trade inthis raw material is directly linked to the economic health of industrializedcountries This explains the abrupt variations experienced in the past, which mayoccur again

In 1989, iron ore accounted for 16% of dry bulk seaborne trade with 357 Mt inexcess of 38 Mt compared to 1987 and the largest figure ever met (Fig 3)

Six major exporting countries provided 90% of this tonnage: Brazil (100 Mt),Australia (100 Mt), Canada (25 Mt), India, Sweden and Liberia The leadingimporter is Japan with 115 Mt This traffic is characterized by long transportationdistances (5400 miles approximately) The trend toward ever larger ships iscontinuing 70% of the tonnage was transported by ships over 100,000 dwt; athird of the bulk carrier fleet was used for this purpose Short-haul trades inEurope and Asia were served by ships in the 40,000 to 80,000 dwt range

In the years ahead, very large ore carriers (over 300,000 dwt) should account for

an increasingly larger share of long-haul trade (Brazil, Europe, Japan)

In 1989 coal accounted for 14% of dry bulk seaborne trade with 315 Mt,thelargest figure ever met,in excess of 32 Mt compared to 1987 The evolution ?fthis trade is more stable than the iron ore trade (Fig 3) The leading exporters Interms of maritime transport are Australia (100 Mt), the United States and Canada(90 Mt), Poland (34 Mt) and South Africa (42 Mt) The amount exported by each

of these country may vary considerably from year to year

Canada and the United States are the exporters providing the excess of tonnage

in 1988 and 1989 The leading importer is Japan with 103 Mt

The average shipping distance is 5800 miles

Bulk carriers over 100,000 dwt continue to increase their share of traffic (45%)from Australia, South Africa and the United States to Europe and Japan Short-haul trade is primarily ensured by ships under 60,000 dwt

111.3GRAIN

In 1988 and 1989, this traffic remained stable in excess of 10 Mt compared to

1987 In 1989 grain accounted for 9% of dry bulk seaborne trade with 195 Mt.The largest figure ever met was 207 Mt in 1984

Fifty percent of this tonnage was wheat This traffic is very dependent on theharvests of exporting and importing countries (Fig 3)

The main exporters are the United States (110 Mt), Canada (24 Mt), Argentina(15 Mt) and Australia (11 Mt) The leading importers are always the U.S.S.R.(32 Mt), Japan (31 Mt),and China (22 Mt) The average shipping distance is

The list of other commodities transported primarily by bulk carriers is long Itincludes sugar (30 Mt), manganese (3.1 Mt), gypsum (5.7 Mt), salt (8.3 Mt),sulphur (5.6 Mt), limestone (1 Mt), scrap iron (12.1 Mt), expellers (6.5 Mt), cement(22.3 Mt), nonferrous metal (8.5 Mt), oil coke (15.8 Mt), tapioca (5.1 Mt), etc

It is also necessary to include liquefied gases LNG account for 45 Mt, LPG accountfor 25 Mt, Ammonia gas for 7.5 Mt and other petrochemical gases for 3 Mt

GENERAL CARGO

Statistics on overall commodities trade are very fragmentary because of thewide diversity, however, it is estimated at about 1250 million tonnes Thistonnage includes foodstuffs (fresh,refrigerated,frozen),chemicals, finishedproducts or manufacturated products such as cars,etc These high valueproducts are mainly transported by ships on regular routes with tight schedules

It is especially for this type of cargo that the container ship introduced arevolutiony method of transportation coupled with increased security

Tonnage transported by containers was estimated at 390 Mt in 1988 and 430 Mt

in 1989 representing more than a third of all general cargo traffic In 1988, thenumber of 20-foot container (12 to 15 tonnes) movements in all different portswas estimated at 73 million, i.e up 6 million from 1987 and 20 million from 1984.15% of these movements apply to empty containers

In 1990, seven of the ten largest container ports in the world, excludingRotterdam, New York and Los Angeles,are located in the Far East As early as

1985, Japan, Thailand, Hong Kong, Singapore and South Korea had trafficequivalent to that of Europe Estimates show that more than 80% of the highvalue cargoes shipped by sea between developed countries are transported bycontainer

PASSENGER TRANSPORT

Even if the passenger transport traffic is statistically negligible,its development is

so strong that it is worthy of note

Two types of activities prevail:

- Passenger and car transportation on short crossings ( Scandinaviancountries,cross-Channel,islands,etc.),by vessels usually known asFerries

- The cruise industry which has experienced extraordinary growth and

it is estimated that between 1988 and 1989 this traffic increased 20%

FISH ING

Fishing represents a marine activity which is important and cannot be ignored.ln 1987,nearly 92.7 Mt of fish were caught by the various fishing fleets all over the world.The main species are the following:

Alaska pollack 6.7 Mt Skipjack tuna 0.98 MtJapanese pilchard 5.3 Mt S Africa anchovy 0.96 MtSouth America pilchard 4.6 Mt Gulf menhaden 0.91 MtChilean jack mackerei 2.6 Mt Yellowfin tuna 0.82 MtPeruvian anchovy 2.1 Mt Blue whiting O.71 MtAtlantic cod 2.1 Mt Atlantic mackerei 0.65 MtChub mackerei 1.6 Mt European anchovy 0.64 MtAtlantic herring 1.6 Mt Pacific cupped oyster 0.61 MtCapellin 1.1 Mt Common carp 0.57 MtEuropean pilchard 1.1 Mt

Among the most important commercial species, the pilchard contributed wellover 10 Mt to world supplies

Among the world's leading fishing countries, Japan and the U.S.S.R are in thetop two places

Japan 11.8 Mt Philippines 1.9 MtU.S.S.R 11.2 Mt Norway 1.9 MtChina 9.4 Mt North Korea 1.7 MtU.S.A 5.7 Mt Denmark 1.7 MtChile 4.8 Mt Iceland 1.6 MtPeru 4.6 Mt Canada 1.4 MtIndia 2.9 Mt S Africa & Namibia 1.4 MtSouth Korea 2.8 Mt Mexico 1.4 MtIndonesia 2.5 Mt Spain 1.4 MtThailand 2.1 Mt Taiwan 1.2 MtThe first European country is Norway at the 12th place with 1.9 Mt Denmark isranked 14th, Spain 19th, Great Britain 21 st and France 23rd (0.8 Mt)

The statistics in this chapter provide an idea of volumes shipped by sea Theyshow the changes that occur from one year to the next and underline thesometimes sudden and unpredictable nature of these changes They clearlyshow the difficulties faced by shipowners have in forecasting the number andtype of vessels ships best suited to transportation of a given commodity

REFERENCES

- "Review 1987-1989", Fearnleys, OSLO

- "Maritime transports 1989 ",OCDE,Paris, 1990

- FAa Yearbook of Fishery Statistics

V.1 ORE - OIL CARRIERS

V.2 ORE - BULK - OIL CARRIERS

LIQUID - GAS CARRIERS

WORLD FLEET FIG 4

Shipbuilding is dependent on commissioning, which is in turn heavily dependent

on the economic factors governing the main shipping trade trends

The overall development of merchant vessel technology is marked by twosuccessive trends:

1) the first one is to built specific vessel for specialised trade;

2) the second one is to built larger and larger vessels

Economic factors govern the appearance of specialized ships and areresponsible for their development (increased tonnage, optimal speed,complexity of internal facilities, etc.) When trade increases on a given route, aspecialized ship is by definition better suited to this route's characteristics(dimension, tonnage, speed, etc.) This trend to specialization has alwaysexisted, and shipowners have always adapted vessels to the services provided.When shipowners feel that a specific trade will continue to grow, they willdemand larger ships However, this capacity can be restricted by factors specific

to the route in question

The best example of the very large or ultra large vessel is oil tankers, but thistrend is also very marked for ore carriers and liquid-gas carriers Anothersignificant example is container ships, where up to 2500 TEU ( Totally EnclosedUnits) ships emerged only a few years after this type of vessel appeared

For shipowners, large tonnage specialized ships are the best economic solution,but also carries a certain risk If trade develops in a different direction from theone forecast, these ships can lose much of their market value In early 1986, astudy estimated that the existing ULCC (an oil tanker over 320,000 dwt) fleet thatcost some 6 billion dollars to build was worth less than 600 million dollars

To limit these risks, combined bulk-oil carriers appeared around 1970 and hadvarying degrees of success The different types can be used to carry variouscommodities at short notice

Currently, few ships of this type are on order because of the stringency ofInternational Maritime Organization (IMO) regulations

Another example is polythermal refrigerated ships suitable for transporting suchcargo as frozen freight at -30°C or fruit and fresh produce at +5 to +8°C

In the 1970s, some shipyards offered standardized ships, in particular to replacethe famous Liberty ships These attempts were generally unsuccessful despitelow construction and operating costs, since shipowners rarely found vessels thatmet their immediate needs, and were replaced by specialised or bulk cargovessels

Figure 4 shows the evolution of the total world fleet for ships over 100 grosstons The continual increase in tonnage for more than 15 years and thestabilization that followed are clear.

World tonnage at the end of 1989 was around 410 million gross tons,in excess

1949: 30,000 dwt; 1953: 33,000 dwt; 1956: 45,000 dwt; 1962:100,000dwt;1967: 200,000 dwt; 1969: 310,000 dwt; 1972: 372,000 dwt; 1975: 500,000 dwt

The evolution of this fleet was linked to fluctuations in world petroleum productconsumption, international trade, the recession and political crises

Oil tanker size was long limited by the Suez Canal, through which most of the oilimported by Europe was shipped Before its closure in June 1967, fully-loaded100,000 dwt oil tankers could not travel through the Canal The trend towardever larger ships was linked to the need to continually lower the cost of thetonne transported Until 1975, tankers had to travel the Cape route Lowershipping costs offset the cost of the longer trip

The result was ever larger oil tankers, up to 550,000 dwt Just before the crisis,1,000,000 dwt tankers were being designed

In the 300,000 to 400,000 dwt range, 20 tankers were available in 1975, 43 in

1976 and 65 in 1977 In 1975, 5 tankers over 400,000 dwt were available, asopposed to 29 in 1977

A distinction was soon made between two classes of supertanker: VLCCs 0IeryLarge Crude Carriers), between 160,000 and 320,000 dwt, and ULCCs (UltraLarge Crude Carriers), over 320,000 dwt

The capacity of the long-haul tanker fleet (ships over 10,000 dwt) increasedconsiderably until 1977, the last year when the effect of orders placed prior to

1973 was felt It then rapidly decreased (Fig 5)

WORLD FLEET FIG 5 OIL TANKERS (>10000 Dwt)

The increasing excess capacity caused by slower oil consumption since 1973peaked in 1982-1983 and had still not been absorbed in 1987 (Fig 5) despite anintensive scrapping program, decommissioning of part of the fleet, and shipsnavigating at reduced speed or converted into floating storage facilities (Fig 6).

After the second oil crisis, 350 of the 700 VlCCs and UlCCs in existence,almost all under 10 years old, were unused This represented an investment ofaround 14 billion dollars that was theoretically waste Wholesale scrapping wasthe only solution Between 1978 and 1983, 200 VlCC/UlCCs were scrapped,

65 in 1983 alone

Thus, most 550,000 dwt tankers - the pride and joy of oil companies - werescrapped after only 5 to 7 years of operation Only two were still in service in

1990 Another one was laid up and the last one used for storage

To the effects of the sharp reduction in the oil tonnage transported were addedthose stemming from changes in the geographic distribution of producingcountries Periodically, demand from the Gulf increased or decreased suddenly

in accordance with crude price fluctuations caused by OPEC meetings Thesecyclical ups and downs continued until 1986

The main supply trends for 1989 are given in Figure 7; the change in comparison

to 1979 is obvious

In 1980,as a result of work on the Suez canal (reopened in 1975) modificationsenabled empty 300,000 dwt and fully-loaded 150,000 dwt tankers to travelthrough

After 1983, orders commenced being to be placed for tankers just under100,000 dwt, suitable for almost all traffic Their use was more in line with marketconditions Furthermore, tankers of this size available on the market were old, ordecommissioned when the new SOlAS and MARPOl (inert gas, crude-oilwashing, etc.) regulations came into force

In 1987, excess tonnage was still high, especially in the 150,000 to 320,000 dwttanker range, but since 1988 the situation has improved At the beginning of

1989, according to experts, this excess is rather overestimated and will bereasonably stable in the futuro

Figures 8 and 9 show the evolution of the French long-haul oil tanker fleet

This discussion of tankers covered the evolution of long-haul supertankers In

1989, 2337 of these ships represented close to 239 Mt However, many smalltankers exist and at the same date there were 3645 under 10,000 dwtrepresenting 11 Mt

The total world tanker fleet,including oil/chemical tankers, over 100 gross tonswas 6383 in 1989 for close to 250 Mt (130 million gross tons).

The main problem of tanker construction is finding the most economical solutionfor the metal structure while complying with safety requirements Longitudinaland transverse strength, buckling strength, vibration resistance, and the quality

of the steel used are studied with great care The same is applicable to ballastingand tank washing

Loading and discharging must be performed very quickly, and even the mostminor details of pumping facilities must be carefully designed (high-capacitypumps: 4000 to 5000 m3/hour)

The loaded speed of large tankers has always been relatively low (15 to

16 knots) and has decreased considerably as the price of fuel has risen

The rating needed can be obtained with low- or medium-speed diesel engines,depending on the size of the vessel The very large tankers were propelled bysteam turbines Up to 300,000 dwt, they generally had a single propeller The550,000 dwt tankers had two propellers and the design for 1 million tonne dwttankers included three

The main factor influencing tanker design is the constant demand for improvedsafety and better environmental protection Without going into exhaustive detailabout IMO regulations, requirements cover segregated ballast, smaller cargotanks, inert gas systems and residue tanks

Efforts to improve hydrodynamics also modified tanker appearance such as thebulbous bow,etc

Some significant tanker dimensions are given in Table 3

FRANCE FIG 8 OIL TANKERS (>10000 Dwt)

ORE CARRIERS

Ore carriers are extremely specialized ships that are difficult to adapt to a tradeother than heavy ore, or even sometimes to a route other than that for whichthey were originally designed They have very high double bottoms to raise thecenter of gravity of the cargo and a double hull The volume of the holds aresignificantly low because of the weight of the ore (density: 1.8 to 2.8) The ballastcompartments are large The structural problems are fairly similar to those of oiltankers The athwartship bulkheads are often widely spaced Thehydrodynamics of these ships have also been improved They do not have cargohandling equipment

The existence of some very large vessels of this type means that port facilitiesmust also be specially designed for ore transport and handling

Some ship dimensions are given in Table 4

BULK CARRIERS

Bulk carriers are vessels with a very large loading volume that carry light- tomedium-density cargoes (coal, grain, bauxite, sugar, etc.)

The ballast tanks are relatively small and the bulkheads are not usually designed

to support liquid loads

They can transport a wide variety of bulk products, for example ore in alternateholds and coal and grain in the side upper holds and space

Special ships are built for some specific routes For example, the "Panama bulkcarrier" (Panamax) is specially designed for Panama canal trade with a maximumbreadth of 32.24 m

Some specific problems should be mentioned:

- For grain transportation,internationnal regulations onstability, protection against shifting and ease of loading must berespected;

- The ballast tanks must have sufficient tonnage to satisfy all ballastnavigation conditions

This type of transportation requires suitable large handling and storage facilities

in the loading and discharging ports At present, bulk fleet prospects are muchmore encouraging than some years ago and the considerable excess capacityexisting decreased very quickly since 1988

The evolution of the world ore and bulk carrier fleet is given in Figure 10 Somedimensions are given in Table 4 In 1989, 4708 ships of this type representedclose to 110 million gross tons.

COMBINED CARRIERS

The advantage of combined carriers is their ability to transport either liquid ordry bulk, which gives them a better market position and enables them to takeadvantage of the most favourable conditions There are two main types ofcombined carriers: ore-oil carriers and ore-bulk-oil carriers

Currently, prospects for these ships are gloomy and their use continues todecline With the exception of very specific cases, the investment expenditure istoo great to be offset by their increased operating flexibility However, the future

of combined carriers depends on development prospects for oil and dry bulktransport, and trend reversals do sometimes occur

The evolution of the world combined carrier fleet is given in Figure 11 In 1989,

353 ships of this type represented 20 million gross tons

V.1 ORE-OIL CARRIERS

Ore and oil cannot be carried at the same time, but the two types of cargo cansucceed one another The design of an ore-oil carrier is derived from that ofspecialized ore carriers

The tonnage available in this type of ship decreased by almost 50% between

1979 and 1988

The fleet has aged and has lost its ability to compete with modern ships Veryfew new ships have been delivered in the last few years In 1990, however, avery large (300,000 dwt) ore-oil carrier was built in Taiwan

WORLD FLEET FIG 11

LIQUID-GAS CARRIERS

On these highly specialized ships, innovation succeeded innovation very quickly,and size increased rapidly These ships transport liquefied petroleum gas (LPG),liquefied natural gas (LNG) or petrochemical gas

There are three types of ship in accordance with the means used to transportthe gas:

- under pressure: small ships, since the pressure required (4.5 bar forbutane, 18 bar for ammonia) means that tank weight and pricebecomes prohibitive;

- very low density cargo,

- large ballast volume for in ballast voyages,

- hull strength,

- choice of steels,

- tanks must be gas-tight and insulated,

- loading and unloading

- the engine and the boilers of LNG carriers operating sometimes

4 vessels of more than 120,000 m3 were in fact recommissioned Furthermore,the first methane carrier built for 6 years was delivered, and will be followed by

5 others for shipment of gas to Japan

At the same time, all LPG carriers (>10,000 m3) including 152 ships (6.6 millionm3) were in use This fleet is, on the whole, relatively new Strong growth ispredicted for the next five years and 38 ships have been ordered at thebeginning of 1990

Figure 12 gives the world's increase in the number of liquid-gas carriers In 1989,

789 ships represented 10 million gross tons Some dimensions of these vesselsare given in Table 5

WORLD FLEET FIG 12

LNG CARRIER (Navires Ports et Chantiers - Juin 87)

REFRIGERATED CARGO VESSEL (The Motor Ship - Nov 86)

REFRIGERATED SHIPS

Two types of refrigerated freight transport existed until 1955:

- bananas, fruit and fresh produce at +5 to +8°C;

- frozen freight at -25 to -30°C

The uncertainties affecting this type of transport led shipowners to change over

to polythermal ships, Le ships suitable for both types of trade

Operating flexibility won out over profitability in the strictest sense of the word,since this type of vessel is a compromise; the large volume reserved forventilation is unnecessary for frozen freight and the refrigerating capacity isexcessive for fruit and fresh produce transport needs

These ships have a shallow draft and are relatively fast The refrigerating facilitiesare very sophisticated from the point of view of regulation Excess tonnage wasconsiderable at the beginning of 1985 but, after a period of extensive renewal,this fleet experienced satisfactory years since 1987 The two largest reefers everbuilt were delivered in 1989 (12,500 dwt for a capacity of 700,000 cubic feet)

At this time 1402 of these ships represented 65 million gross tons

CONTAINER SHIPS

The transport capacity of container ships is expressed in TEU (Twenty footEquivalent Unit) which is the size of the first standardized boxes used Whenthese units are stacked cellular containers, the ship is sometimes referred to as alift-on, lift-off ship These vessels have experienced spectacular growth sincetheir introduction in 1967 on regular routes between Europe and North America(solid, boxed, bulk, liquid, etc freight)

The trend to very large size also extended to these ships They were originallyhigh-speed ships (21 to 26 knots), but this speed decreased as a result of theenormous size and increased fuel costs However,since 1989, larger and fastercontainer ships were once again in demand (24 knots) These will serve only afew ports supplying dense industrial areas

Some years ago these ships had a rather shallow draft to satisfy the loading andunloading conditions (height in relation to dock)

The holds have to be adapted to containers, which are bulky,and they arearranged in wells whose dimensions match those of the containers; the latter arestacked by sliding them into metal guides

The need for quick handling resulted in the development of sophisticatedhandling and storage equipment that is sturdy and easy to use

WORLD FLEET FIG 13

TABLE 6 : CONTAINER SHIPS

MULTIPURPOSE RO I RO SHIP (The Motor Ship - April 88)

Ports had to set aside large sections of dockland area and install lifting, storageand handling facilities suitable for containers The ships do not have their ownhandling equipment.

The first container ships in 1965 could carry 800 containers Some containerships are now able to transport more than 3000 containers and even

4000 Single screw container ship engines can be rated up to 67,000 hp

Some dimensions are given in Table 6 Figure 13 gives the world evolution ofcontainer ships Growth has been almost constant In 1989, more than

1100 container ships represented more than 22 million gross tons and had acapacity of more than 1.5 million standard 20-foot containers

RO/RO SHIPS

Horizontal handling ships where cargo is loaded and unloaded using rollingstock or consists of semitrailers, trucks or cars are called RO/RO (roll-on, roll-off)ships

Loading is performed through side doors or using bow and stern access ramps.Internal ventilation must be very efficient

These ships do not rely on port handling facilities, but require special dockfacilities and relatively complex access ramps

They are generally used on short-haul routes (Great Britain, European andMediterranean trade) and very profitable routes (North America-Europe-Japan)

In 1989, 971 of these ships represented 7 million gross tons from which

288 were used only for car or truck transport representing 3.9 million gross tons

WORLD FLEET FIG 14

TABLE 7 : CARGO SHIPS