Ship

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Ship
From Wikipedia, the free encyclopedia
(Redirected from Ships)

For other uses, see Ship (disambiguation).

Italian full-rigged ship Amerigo Vespucci in New ork !ar"or, #$%&

In modern parlance a ship has "een any large "uoyant watercraft' Ships are generally distinguished from "oats "ased on si(e, shape andcargo or passenger capacity' Ships are used on lakes, seas, and ri)ers for a )ariety of acti)ities, such as the transport of people or goods,fishing, entertainment, pu"lic safety, and warfare' !istorically, a *ship* was a sailing )essel with at least three s+uare-rigged masts and a full "owsprit' Ships and "oats ha)e de)eloped alongside humanity' In armed conflict and in daily life they ha)e "ecome an integral part of modern commercial and military systems' Fishing "oats are used "y millions of fishermen throughout the world' ,ilitary forces operate )essels for com"at and to transport and support forces ashore' -ommercial )essels, nearly ./,000 in num"er, carried %'1 "illion tons of cargo in 200%'3#4 5s of 20##, there are a"out #01,.01 ships with I,6 num"ers in the world'324 Ships were always a key in history7s great e8plorations and scientific and technological de)elopment' Na)igators such as 9heng !e spread such in)entions as the compass and gunpowder' Ships ha)e "een used for such purposes as coloni(ation and the sla)e trade, and ha)e ser)ed scientific, cultural, and humanitarian needs' 5fter the #&th century, new crops that had come from and to the 5mericas )ia the :uropean seafarers significantly contri"uted to the world7s population growth' 3.4 ,aritime transport has shaped the world7s economy into today7s energy-intensi)e pattern'
Contents
3hide4

• • o o o o • o o o o • o o o o o • o o • o o

# Nomenclature 2 !istory 2'# ;rehistory and anti+uity 2'2 Renaissance 2'. Speciali(ation and moderni(ation 2'1 <oday . <ypes of ships .'# Inland and coastal "oats .'2 Seagoing commercial )essels .'. Special purpose )essels .'1 Na)al )essels 1 5rchitecture 1'# !ull 1'2 ;ropulsion systems 1'. Steering systems 1'1 !olds, compartments, and the superstructure 1'/ :+uipment / =esign considerations /'# !ydrostatics /'2 !ydrodynamics & >ifecycle &'# =esign &'2 -onstruction

o o • • o o o o • • • • •

&'. Repair and con)ersion &'1 :nd of ser)ice % ,easuring ships ? Ship pollution ?'# 6il spills ?'2 @allast water ?'. :8haust emissions ?'1 Ship "reaking $ @uoyancy #0 See also ## Notes #2 References #. :8ternal links

Nomenclature3edit4

,ain parts of ship' 1A Smokestack or FunnelB 2A SternB3A ;ropeller and RudderB 4A ;ortside (the right side is known asstar"oard)B 5A 5nchorB 6A @ul"ous "owB 7A @owB 8A =eckB9A Superstructure

For more details on this topic, see Glossary of nautical terms.

Ships can usually "e distinguished from "oats "ased on si(e and the ship7s a"ility to operate independently for e8tended periods'314 5 commonly used rule of thum" is that if one )essel can carry another, the larger of the two is a ship'3/4 =inghies are carried on sailing yachts as small as ./ feet (#0'&% m), clearly not shipsB this rule of thum" is not foolproof' In the age of sail, a *ship* was a sailing )essel with at least three s+uare-rigged masts and a full "owspritB other types of )essel were also defined "y their sailplan, e'g' "ar+ue, "rigantine, etc' 5 num"er of large )essels are usually referred to as "oats' Su"marines are a prime e8ample'3&4 6ther types of large )essel which are traditionally called "oats are the Creat >akes freighter, the ri)er"oat, and the ferry"oat'
3citation needed4

<hough large enough to carry their own "oats and hea)y cargoes, these )essels are designed for

operation on inland or protected coastal waters' In most maritime traditions ships ha)e indi)idual names, and modern ships may "elong to a ship class often named after its first ship' In :nglish, a ship is traditionally referred to as *she*, e)en if named after a man, "ut this is not uni)ersal usageB some Dournalistic style guides ad)ise using *it*,3%4 others ad)ise *she* and *her*'3?43$4

!istory3edit4
Further information: Maritime history

Prehistory and antiquity3edit4

5 raft is among the simplest "oat designs'

<he first known )essels date "ack to the Neolithic ;eriod, a"out #0,000 years ago, "ut could not "e descri"ed as ships' <he first na)igators "egan to use animal skins or wo)en fa"rics as sails' 5ffi8ed to the top of a pole set upright in a "oat, these sails ga)e early ships range' <his allowed men to e8plore widely, allowing for the settlement of 6ceania for e8ample (a"out .,000 years ago)' @y around .000 @-, 5ncient :gyptians knew how to assem"le wooden planks into a hull'3#04 <hey used wo)en straps to lash the planks together,3#04 and reedsor grass stuffed "etween the planks helped to seal the seams'3#043##4 <he Creek historian and geographer 5gatharchides had documented ship-faring among the early :gyptiansA !uring the prosperous period of the "ld #ingdom, bet$een the %&th and '(th centuries ). *., the ri+er,routes $ere -ept in order, and .gyptianships sailed the /ed Sea as far as the myrrh,

country.

3#24

Sneferu7s ancient cedar wood ship ;raise of the <wo >ands is the first reference recorded

(2&#. @-:) to a ship "eing referred to "y name'3#.4 <he ancient :gyptians were perfectly at ease "uilding sail"oats' 5 remarka"le e8ample of their ship"uilding skills was the Ehufu ship, a )essel #1. feet (11 m) in length entom"ed at the foot of the Creat ;yramid of Ci(a around 2/00 @- and found intact in #$/1' It is known that ancient Nu"iaF58um traded with India, and there is e)idence that ships from Northeast 5frica may ha)e sailed "ack and forth "etween IndiaFSri >anka and Nu"ia trading goods and e)en to ;ersia, !imyar and Rome'3#14 5ksum was known "y the Creeks for ha)ing seaports for ships from Creece and emen'3#/4 :lsewhere in Northeast 5frica, the ;eriplus of the Red Sea reports that Somalis, through their northern ports such as 9eila and @er"era, were trading frankincense and other items with the inha"itants of the 5ra"ian ;eninsula well "efore the arri)al of Islam as well as with then Roman-controlled :gypt'3#&4 5 panel found at ,ohenDodaro depicted a sailing craft' Gessels were of many typesB their construction is )i)idly descri"ed in the ukti Ealpa <aru, an ancient Indian te8t on ship"uilding' <his treatise gi)es a technical e8position on the techni+ues of ship"uilding' It sets forth minute details a"out the )arious types of ships, their si(es, and the materials from which they were "uilt' <he ukti Ealpa <aru sums up in a condensed form all the a)aila"le information' <he ukti Ealpa <aru gi)es sufficient information and dates to pro)e that, in ancient times, Indian ship"uilders had a good knowledge of the materials which were used in "uilding ships' In addition to descri"ing the +ualities of the different types of wood and their suita"ility for ship"uilding, the ukti Ealpa <aru gi)es an ela"orate classification of ships "ased on their si(e' @y a"out 2000 @-, the ,inoan ci)ili(ation in -rete had e)ol)ed into a na)al power e8ercising effecti)e control of the sea in the eastern ,editerranean'3#%4 <he oldest disco)ered sea faring hulled "oat is the :gyptian Hlu"urun shipwreck off the coast of <urkey, dating "ack to #.00 @'-'3#?4 <he ;hoenicians, the first to sail completely around 5frica, and Creeks gradually mastered na)igation at sea a"oard triremes, e8ploring and coloni(ing the ,editerranean )ia ship' 5round .10 @-, the Creek na)igator ;ytheas of ,assalia )entured from Creece to Western :urope and Creat @ritain'3#$4 In the course of the 2nd century @-, Rome went on to destroy -arthage and su"due the!ellenistic kingdoms of the eastern ,editerranean, achie)ing complete mastery of the inland sea, that they called Mare 0ostrum' <he monsoon wind system of the Indian 6cean was first sailed "y Creek na)igator :udo8us of -y(icus in ##? @-'3204 With .00 Creek ships a year sailing "etween Roman :mpire and India, the annual trade may ha)e reached .00,000 tons'32#4

In -hina, "y the time of the 9hou =ynasty ship technologies such as stern mounted rudders were de)eloped, and "y the !an =ynasty, a well kept na)al fleet was an integral part of the military' Ship technology ad)anced to the point where "y the medie)al period, water tight compartments were de)eloped'

Roman trireme mosaic from -arthage,@ardo ,useum, <unis'

<he Swahili people had )arious e8tensi)e trading ports dotting the coast of medie)al :ast 5frica and Creat 9im"a"we had e8tensi)e trading contacts with-entral 5frica, and likely also imported goods "rought to 5frica through the Southeast 5frican shore trade of Eilwa in modern-day <an(ania'3224 It is known "y historians that at its height the ,ali :mpire "uilt a large na)al fleet under :mperor ,ansa ,usa in the late #.th and early #1th century' 32.45ra"ic sources descri"e what some consider to "e )isits to the New World "y a ,ali fleet in #.##'3214

<he @attle of >epanto, #/%#, na)al engagement "etween allied -hristian forces and the 6ttoman Na)y'

@efore the introduction of the compass, celestial na)igation was the main method for na)igation at sea' In -hina, early )ersions of the magnetic compass were "eing de)eloped and used in na)igation "etween #010 and ###%'32/4 <he true mariner7s compass, using a pi)oting needle in a dry "o8, was de)eloped in :urope no later than #.00'32&432%4

Renaissance3edit4
Hntil the Renaissance, na)igational technology remained comparati)ely primiti)e' <his a"sence of technology did not pre)ent some ci)ili(ations from "ecoming sea powers' :8amples include the maritime repu"lics of Cenoaand Genice, !anseatic >eague, and the @y(antine na)y' <he Gikings used their knarrs to e8plore North 5merica, trade in the @altic Sea and plunder many of the coastal regions of Western :urope'

5 replica of the carrack Santa Mar1a of -hristopher -olum"us

<owards the end of the #1th century, ships like the carrack "egan to de)elop towers on the "ow and stern' <hese towers decreased the )essel7s sta"ility, and in the #/th century, the cara)el, designed "y the ;ortuguese, "ased on the 5ra"ic 2arib which could sail closer to the wind, "ecame more widely used' <he towers were gradually replaced "y the forecastle and sterncastle, as in the carrack Santa Mar1a of -hristopher -olum"us' <his increased free"oard allowed another inno)ationA the freeing port, and the artillery associated with it'

5 Iapanese atake"une from the #&th century

In the #&th century, the use of free"oard and freeing ports "ecame widespread on galleons' <he :nglish modified their )essels to ma8imi(e their firepower and demonstrated the effecti)eness of their doctrine, in #/??, "y defeating theSpanish 5rmada' 5t this time, ships were de)eloping in 5sia in much the same way as :urope' Iapan used defensi)e na)al techni+ues in the ,ongol in)asions of Iapan in #2?#' It is likely that the ,ongols of the time took ad)antage of "oth :uropean and 5sian ship"uilding techni+ues' =uring the #/th century, -hina7s ,ing =ynasty assem"led one of the largest and most powerful na)al fleet in the world for the diplomatic and power proDection )oyages of 9heng !e' :lsewhere in Iapan in the #/th century, one of the world7s first iron-clads, *<ekkJsen* (鉄甲船), literally meaning *iron ships*,32?4 was also de)eloped' In Iapan, during the Sengoku era from the

fifteenth to #%th century, the great struggle for feudal supremacy was fought, in part, "y coastal fleets of se)eral hundred "oats, including the atake"une'

,odel of a medie)al ,ogadishanship'

=uring the 5ge of the 5Duuraan, the Somali sultanates and repu"lics of ,erca, ,ogadishu, @arawa, !o"yo and their respecti)e ports flourished, enDoying a lucrati)e foreign commerce with ships sailing to and coming from 5ra"ia, India, Genetia,32$4 ;ersia, :gypt, ;ortugaland as far away as -hina' In the #&th century, =uarte @ar"osa noted that many ships from the Eingdom of -am"aya in what is modern-day India sailed to ,ogadishu with cloth and spices, for which they in return recei)ed gold, wa8 and i)ory' @ar"osa also highlighted the a"undance of meat, wheat, "arley,horses, and fruit on the coastal markets, which generated enormous wealth for the merchants'3.04 ,iddle 5ge Swahili Eingdoms are known to ha)e had trade port islands and trade routes 3.#4 with the Islamic world and 5sia and were descri"ed "y Creek historians as *metropolises*' 3.24 Famous 5frican trade ports such as ,om"asa, 9an(i"ar, and Eilwa3..4 were known to -hinese sailors such as 9heng !eand medie)al Islamic historians such as the @er"er Islamic )oyager 5"u 5"dullah i"n @attua'3.14 In the #1th century -: Eing 5"u"akari I, the "rother of Eing ,ansa ,usa of the ,ali :mpire is thought to ha)e had a great armada of ships sitting on the coast of West 5frica'3./4 <his is corro"orated "y i"n @attuta himself who recalls se)eral hundred ,alian ships off the coast'3.&4 <his has led to great speculation, with historical e)idence, that it is possi"le that ,alian sailors may ha)e reached the coast of ;re--olum"ian 5merica under the rule of 5"u"akari II, nearly two hundred years "efore -hristopher -olum"us 3.%4 and that "lack traders may ha)e "een in the 5mericas "efore -olum"us'3.?4

Replica of ,agellanKs Victoria' Ferdinand ,agellan led the first e8pedition thatcircumna)igated the glo"e in #/#$-#/22'

Fifty years "efore -hristopher -olum"us, -hinese na)igator 9heng !e tra)eled the world at the head of what was for the time a huge armada' <he largest of his ships had nine masts, were #.0 metres (1.0 ft) long and had a "eam of // metres (#?0 ft)' !is fleet carried .0,000 men a"oard %0 )essels, with the goal of "ringing glory to the -hinese emperor' <he carrack and then the cara)el were de)eloped in I"eria' 5fter -olum"us, :uropean e8ploration rapidly accelerated, and many new trade routes were esta"lished'3.$4 In #1$?, "y reaching India, Gasco da Cama pro)ed that the access to the Indian 6cean from the 5tlantic was possi"le' <hese e8plorations in the 5tlantic and Indian 6ceans were soon followed "y France, :ngland and the Netherlands, who e8plored the ;ortuguese and Spanish trade routes into the ;acific 6cean, reaching 5ustralia in #&0& and New 9ealand in #&12'3104 5 maDor sea power, the =utch in #&/0 owned #&,000 merchant ships'31#4 In the #%th century =utch e8plorers such as 5"el <asman e8plored the coasts of 5ustralia, while in the #?th century it was @ritish e8plorer Iames -ook who mapped much of ;olynesia'

Specialization and

odernization3edit4

<he @ritish !,S Sand$ich fires at the French flagship )ucentaure (completely dismasted) at the "attle of <rafalgar (#?0/)' <he )ucentaure also fights !,S Victory("ehind her) and !,S 3emeraire (left side of the picture)' In fact, !,S Sand$ich ne)er fought at <rafalgar, it7s a mistake from5uguste ,ayer, the painter'3124

;arallel to the de)elopment of warships, ships in ser)ice of marine fishery and trade also de)eloped in the period "etween anti+uity and the Renaissance' Still primarily a coastal endea)or, fishing is largely practiced "y indi)iduals with little other money using small "oats' ,aritime trade was dri)en "y the de)elopment of shipping companies with significant financial resources' -anal "arges, towed "y draft animals on an adDacent towpath, contended with the railway up to and past the early days of the industrial re)olution' Flat-"ottomed and fle8i"le scow "oats also "ecame widely used for transporting small cargoes' ,ercantile trade went hand-in-hand with e8ploration, self-financed "y the commercial "enefits of e8ploration'

=uring the first half of the #?th century, the French Na)y "egan to de)elop a new type of )essel known as a ship of the line, featuring se)enty-four guns' <his type of ship "ecame the "ack"one of all :uropean fighting fleets' <hese ships were /& metres (#?1 ft) long and their construction re+uired 2,?00 oak trees and 10 kilometres (2/ mi) of ropeB they carried a crew of a"out ?00 sailors and soldiers'

R,S 3itanic departs from Southampton' !er sinking wouldtighten safety regulations

=uring the #$th century the Royal Na)y enforced a "an on the sla)e trade, acted to suppress piracy, and continued to map the world' 5 clipper was a )ery fast sailing ship of the #$th century' <he clipper route fell into commercial disuse with the introduction of steam ships, and the opening of the Sue( and ;anama -anals' Ship designs stayed fairly unchanged until the late #$th century' <he industrial re)olution, new mechanical methods of propulsion, and the a"ility to construct ships from metal triggered an e8plosion in ship design' Factors including the +uest for more efficient ships, the end of long running and wasteful maritime conflicts, and the increased financial capacity of industrial powers created an a)alanche of more speciali(ed "oats and ships' Ships "uilt for entirely new functions, such as firefighting, rescue, and research, also "egan to appear' In light of this, classification of )essels "y type or function can "e difficult' :)en using )ery "road functional classifications such as fishery, trade, military, and e8ploration fails to classify most of the old ships' <his difficulty is increased "y the fact that the terms such as sloop and frigate are used "y old and new ships alike, and often the modern )essels sometimes ha)e little in common with their predecessors'

!oday3edit4

<he *olombo .4press, one of the largest container ships in the world, owned and operated "y !apag->loyd of Cermany

In 200%, the world7s fleet included .1,??2 commercial )essels with gross tonnage of more than #,000 tons,
31.4

totaling #'01 "illion tons'3#4 <hese ships carried %'1 "illion tons of cargo in 200&, a sum that grew "y ?L o)er

the pre)ious year'3#4 In terms of tonnage, .$L of these ships are tankers, 2&L are"ulk carriers, #%L container ships and #/L were other types'3#4

In 2002, there were #,210 warships operating in the world, not counting small )essels such as patrol "oats' <he Hnited States accounted for . million tons worth of these )essels, Russia #'./ million tons, the Hnited Eingdom /01,&&0 tons and -hina 102,?.0 tons' <he 20th century saw many na)al engagements during the two world wars, the -old War, and the rise to power of na)al forces of the two "locs' <he world7s maDor powers ha)e recently used their na)al power in cases such as the Hnited Eingdom in the Falkland Islands and the Hnited States in Ira+' <he si(e of the world7s fishing fleet is more difficult to estimate' <he largest of these are counted as commercial )essels, "ut the smallest are legion'Fishing )essels can "e found in most seaside )illages in the world' 5s of 2001, the Hnited Nations Food and 5griculture 6rgani(ation estimated 1 million fishing )essels were operating worldwide'3114 <he same study estimated that the world7s 2$ million fishermen31/4 caught ?/,?00,000 tonnes (?1,100,000 long tonsB $1,&00,000 short tons) of fish and shellfish that year'31&4

<ypes of ships3edit4
See also: 5ist of types of na+al +essels and 5ist of boat types @ecause ships are constructed using the principles of na)al architecture that re+uire same structural components, their classification is "ased on their function such as suggested "y ;aulet and ;resles', 31%4 which re+uires modification of the components' <he categories accepted in general "y na)al architects areA

• •

!igh-speed craft - ,ultihulls including wa)e piercers, small-waterplane-area twin hull (SW5<!), surface effect ships and ho)ercraft, hydrofoil, wing in ground effect craft (WIC)' 6ff shore oil )essels - ;latform supply )essel, pipe layers, accommodation and crane "arges, non and semi-su"mersi"le drilling rigs, production platforms, floating production storage and offloading units'



Fishing )essels ,otorised fishing trawlers, trap setters, seiners, longliners, trollers M factory ships' <raditional sailing and rowed fishing )essels and "oats used for handline fishing



!ar"our work craft

-a"le layers <ug"oats, dredgers, sal)age )essels, tenders, ;ilot "oats' Floating dry docks, floating cranes, lightership'



=ry cargo ships - tramp freighters, "ulk carriers, cargo liners, container )essels, "arge carriers, Ro-Ro ships, refrigerated cargo ships, tim"er carriers, li)estock M light )ehicle carriers'

• •

>i+uid cargo ships - 6il tankers, li+uefied gas carriers, chemical carriers' ;assenger )essels

>iners, cruise and Special <rade ;assenger (S<;) ships -ross-channel, coastal and har"our ferries' >u8ury M cruising yachts Sail training and multi-masted ships

• •

Recreational "oats and craft - rowed, masted and motorised craft Special-purpose )essels - weather and research )essels, deep sea sur)ey )essels, and ice"reakers'



Su"mersi"les - industrial e8ploration, scientific research, tourist and hydrographic sur)ey'



Warships

Surface warships - deep and shallow draft Su"marines Some of these are discussed in the following sections'

"nland and coastal #oats3edit4
See also: /i+erboat and )arge

;assenger ship of ENln-=Osseldorfer on the ri)er Rhine

,any types of "oats are designed for inland and coastal waterways' <hese are the )essels that trade upon the lakes, ri)ers and canals'

@arges are a prime e8ample of inland )essels' Flat-"ottomed "oats "uilt to transport hea)y goods, most "arges are not self-propelled and need to "e mo)ed "y tug"oats towing or tow"oats pushing them' @arges towed along canals "y draft animals on an adDacent towpath contended with the railway in the early industrial re)olution "ut were out competed in the carriage of high )alue items "ecause of the higher speed, falling costs, and route fle8i"ility ofrail transport' >ake freighters, also called lakers, are cargo )essels that ply the Creat >akes' <he most well-known is the SS .dmund Fit6gerald, the latest maDor )essel to "e wrecked on the >akes' <hese )essels are traditionally called "oats, not ships' Gisiting ocean-going )essels are called *salties'* @ecause of their additional "eam, )ery large salties are ne)er seen inland of the Saint >awrence Seaway' @ecause the smallest of the Soo >ocks is larger than any Seaway lock, salties that can pass through the Seaway may tra)el anywhere in the Creat >akes' @ecause of their deeper draft, salties may accept partial loads on the Creat >akes, *topping off* when they ha)e e8ited the Seaway' Similarly, the largest lakers are confined to the Hpper >akes (Superior, ,ichigan, !uron, :rie) "ecause they are too large to use the Seaway locks, "eginning at the Welland -anal that "ypasses the Niagara Ri)er' Since the freshwater lakes are less corrosi)e to ships than the salt water of the oceans, lakers tend to last much longer than ocean freighters' >akers older than /0 years are not unusual, and as of 200/, all were o)er 20 years of age'31?4 <he SS St. Marys *hallenger, "uilt in #$0& as the 7illiam 8 Snyder, was the oldest laker still working on the >akes until its con)ersion into a "arge starting in 20#.' Similarly, the ..M. Ford, "uilt in #?$? as the 8res2ue 9sle, was sailing the lakes $? years later in #$$&' 5s of 200% the Ford was still

afloat as a stationary transfer )essel at a ri)erside cement silo in Saginaw, ,ichigan'

Sea$oin$ co

ercial %essels3edit4

Main article: *ommercial +essel

<wo modern container ships in San Francisco

-ommercial )essels or merchant ships can "e di)ided into four "road categoriesA fishing, cargo ships, passenger ships, and special-purpose ships'31$4,odern commercial )essels are typically powered "y a single propeller dri)en "y a diesel or, less usually, gas tur"ine engine'3citation needed4, "ut until the mid#$th century they were predominantly s+uare sail rigged' <he fastest )essels may use pump-Det engines'3citation
needed4

,ost commercial )essels ha)e full hull-forms to

ma8imi(e cargo capacity' 3citation needed4 !ulls are usually made of steel, although aluminum can "e used on faster craft, and fi"erglass on the smallest ser)ice )essels'3citation
needed4

-ommercial )essels generally ha)e a crew headed "y

a captain, with deck officers and marine engineers on larger )essels' Special-purpose )essels often ha)e speciali(ed crew if necessary, for e8ample scientists a"oard research )essels' Fishing "oats are generally small, often little more than .0 meters ($? ft) "ut up to #00 metres (..0 ft) for a large tuna or whaling ship' 5"oard a fish processing )essel, the catch can "e made ready for market and sold more +uickly once the ship makes port' Special purpose )essels ha)e special gear' For e8ample, trawlers ha)e winches and arms, stern-

trawlers ha)e a rear ramp, and tuna seiners ha)e skiffs' In 2001, ?/,?00,000 tonnes(?1,100,000 long tonsB $1,&00,000 short tons) of fish were caught in the marine capture fishery'3/04 5ncho)eta represented the largest single catch at #0,%00,000 tonnes (#0,/00,000 long tonsB ##,?00,000 short tons)'3/04 <hat year, the top ten marine capture species also included 5laska pollock, @lue whiting, SkipDack tuna, 5tlantic herring, -hu" mackerel, Iapanese ancho)y, -hilean Dack mackerel, >argehead hairtail, and ellowfin tuna'3/04 6ther species including salmon, shrimp, lo"ster,clams, s+uid and cra", are also commercially fished' ,odern commercial fishermen use many methods' 6ne is fishing "y nets, such as purse seine, "each seine, lift nets, gillnets, or entangling nets' 5nother is trawling, including "ottom trawl' !ooks and lines are used in methods like long-line fishing and hand-line fishing' 5nother method is the use of fishing trap' -argo ships transport dry and li+uid cargo' =ry cargo can "e transported in "ulk "y "ulk carriers, packed directly onto a general cargo ship in "reak-"ulk, packed in intermodal containers as a"oard a container ship, or dri)en a"oard as in roll-on roll-off ships' >i+uid cargo is generally carried in "ulk a"oard tankers, such as oil tankers which may include "oth crude and finished products of oil, chemical tankers which may also carry )egeta"le oils other than chemicals and >;CF>NC tankers, although smaller shipments may "e carried on container ships in tank containers' ;assenger ships range in si(e from small ri)er ferries to )ery large cruise ships' <his type of )essel includes ferries, which mo)e passengers and )ehicles on short tripsB ocean liners, which carry passengers from one place to anotherB and cruise ships, which carry passengers on )oyages undertaken for pleasure, )isiting se)eral places and with

leisure acti)ities on "oard, often returning them to the port of em"arkation' Ri)er"oats and inland ferries are specially designed to carry passengers, cargo, or "oth in the challenging ri)er en)ironment' Ri)ers present special ha(ards to )essels' <hey usually ha)e )arying water flows that alternately lead to high speed water flows or protruding rock ha(ards' -hanging siltation patterns may cause the sudden appearance of shoal waters, and often floating or sunken logs and trees (called snags) can endanger the hulls and propulsion of ri)er"oats' Ri)er"oats are generally of shallow draft, "eing "road of "eam and rather s+uare in plan, with a low free"oard and high topsides' Ri)er"oats can sur)i)e with this type of configuration as they do not ha)e to withstand the high winds or large wa)es that are seen on large lakes, seas, or oceans'

<he Albatun !os, a tuna "oat at work near Gictoria, Seychelles

Fishing )essels are a su"set of commercial )essels, "ut generally small in si(e and often su"Dect to different regulations and classification' <hey can "e categori(ed "y se)eral criteriaA architecture, the type of fish they catch, the fishing method used, geographical origin, and technical features such as rigging' 5s of 2001, the world7s fishing fleet consisted of some 1 million )essels'3114 6f these, #'. million were decked )essels with enclosed areas and the rest were open )essels'3114 ,ost decked )essels were mechani(ed, "ut two-thirds of the open )essels were traditional craft propelled "y sails and oars'3114 ,ore than &0L of all e8isting large

fishing )essels3/#4 were "uilt in Iapan, ;eru, the Russian Federation, Spain or the Hnited States of 5merica'3/24

Special purpose %essels3edit4
Main article: 7eather ship

<he weather ship ,S 8olarfront at sea'

5 weather ship was a ship stationed in the ocean as a platform for surface and upper air meteorological o"ser)ations for use in marine weather forecasting' Surface weather o"ser)ations were taken hourly, and four radiosonde releases occurred daily' 3/.4 It was also meant to aid in search and rescue operations and to support transatlantic flights'3/.43/14 ;roposed as early as #$2% "y the a)iation community, 3//4 the esta"lishment of weather ships pro)ed to "e so useful during World War II that the International -i)il 5)iation 6rgani(ation (I-56) esta"lished a glo"al network of weather ships in #$1?, with #. to "e supplied "y the Hnited States'3/14 <his num"er was e)entually negotiated down to nine'3/&4 <he weather ship crews were normally at sea for three weeks at a time, returning to port for #0 day stretches'
3/.4

Weather ship o"ser)ations pro)ed to "e helpful in wind

and wa)e studies, as they did not a)oid weather systems like other ships tended to for safety reasons' 3/%4 <hey were also helpful in monitoring storms at sea, such as tropical cyclones'3/?4 <he remo)al of a weather ship "ecame a negati)e factor in forecasts leading up to the Creat Storm of

#$?%'3/$4 @eginning in the #$%0s, their role "ecame largely superseded "y weather "uoys due to the ships7 significant cost'3&04 <he agreement of the use of weather ships "y the international community ended in #$$0' <he last weather ship was 8olarfront, known as weather station , (*,ike*), which was put out of operation on # Ianuary 20#0' Weather o"ser)ations from ships continue from a fleet of )oluntary merchant )essels in routine commercial operation'

&a%al %essels3edit4
Main article: 0a+al ship

5merican aircraft carrier :arry S. 3ruman and a replenishment ship

Na)al )essels are those used "y a na)y for military purposes' <here ha)e "een many types of na)al )essel' ,odern na)al )essels can "e "roken down into three categoriesA surface warships, su"marines, and support and au8iliary )essels' ,odern warships are generally di)ided into se)en main categoriesA aircraft carriers, cruisers, destroyers, frigates, cor)ettes, su"marines and amphi"ious assault ships' <he distinction "etween cruisers, destroyers, frigates, and cor)ettes is not rigorousB the same )essel may "e descri"ed differently in different na)ies' @attleships were used during the Second World War and occasionally since then (the last "attleships were remo)ed from the H'S' Na)al Gessel Register in ,arch

200&), "ut were made o"solete "y the use of carrier-"orne aircraft and guided missiles'3&#4 ,ost military su"marines are either attack su"marines or "allistic missile su"marines' Hntil the end of World War II the primary role of the dieselFelectric su"marine was anti-ship warfare, inserting and remo)ing co)ert agents and military forces, and intelligence-gathering' With the de)elopment of the homing torpedo, "etter sonar systems, and nuclear propulsion, su"marines also "ecame a"le to effecti)ely hunt each other' <he de)elopment of su"marine-launched nuclear and cruise missiles ga)e su"marines a su"stantial and long-ranged a"ility to attack "oth land and sea targets with a )ariety of weapons ranging from cluster "om"s to nuclear weapons' ,ost na)ies also include many types of support and au8iliary )essel, such as minesweepers, patrol "oats, offshore patrol )essels, replenishment ships, and hospital ships which are designatedmedical treatment facilities'3&24 Fast com"at )essels such as cruisers and destroyers usually ha)e fine hulls to ma8imi(e speed and maneu)era"ility'
3&.4

<hey also usually ha)e ad)anced electronics and

communication systems, as well as weapons'

5rchitecture3edit4
Further information: 0a+al architecture Some components e8ist in )essels of any si(e and purpose' :)ery )essel has a hull of sorts' :)ery )essel has some sort of propulsion, whether it7s a pole, an o8, or a nuclear reactor' ,ost )essels ha)e some sort of steering system' 6ther characteristics are common, "ut not as uni)ersal, such as compartments, holds, a superstructure, and e+uipment such as anchors and winches'

'ull3edit4

5 ship7s hull endures harsh conditions at sea, as illustrated "y this reefer ship in "ad weather'

For a ship to float, its weight must "e less than that of the water displaced "y the ship7s hull'3&14 <here are many types of hulls, from logs lashed together to form a raft to the ad)anced hulls of 5merica7s -up sail"oats' 5 )essel may ha)e a single hull (called a monohull design), two in the case ofcatamarans, or three in the case of trimarans' Gessels with more than three hulls are rare, "ut some e8periments ha)e "een conducted with designs such as pentamarans' ,ultiple hulls are generally parallel to each other and connected "y rigid arms' !ulls ha)e se)eral elements' <he "ow is the foremost part of the hull' ,any ships feature a "ul"ous "ow' <he keel is at the )ery "ottom of the hull, e8tending the entire length of the ship' <he rear part of the hull is known as the stern, and many hulls ha)e a flat "ack known as a transom' -ommon hull appendages include propellers for propulsion, rudders for steering, and sta"ili(ers to +uell a ship7s rolling motion' 6ther hull features can "e related to the )essel7s work, such as fishing gear and sonar domes' !ulls are su"Dect to )arious hydrostatic and hydrodynamic constraints' <he key hydrostatic constraint is that it must "e a"le to support the entire weight of the "oat, and maintain sta"ility e)en with often une)enly distri"uted weight' !ydrodynamic constraints include the a"ility to withstand shock wa)es, weather collisions and groundings'

6lder ships and pleasure craft often ha)e or had wooden hulls' Steel is used for most commercial )essels' 5luminium is fre+uently used for fast )essels, and composite materials are often found in sail"oats and pleasure craft' Some ships ha)e "een made with concrete hulls'

Propulsion syste s3edit4

5 ship7s engineroom

Main article: Marine propulsion ;ropulsion systems for ships fall into three categoriesA human propulsion, sailing, and mechanical propulsion' !uman propulsion includes rowing, which was used e)en on large galleys' ;ropulsion "y sail generally consists of a sail hoisted on an erect mast, supported "y stays and spars and controlled "y ropes' Sail systems were the dominant form of propulsion until the #$th century' <hey are now generally used for recreation and competition, although e8perimental sail systems, such as the tur"osails, rotorsails, and wingsails ha)e "een used on larger modern )essels for fuel sa)ings' ,echanical propulsion systems generally consist of a motor or engine turning a propeller, or less fre+uently, an impeller or wa)e propulsion fins' Steam engines were first used for this purpose, "ut ha)e mostly "een replaced "y twostroke or four-stroke diesel engines, out"oard motors, and gas tur"ine engines on faster ships' Nuclear reactors producing steam are used to

propel warships and ice"reakers, and there ha)e "een attempts to utili(e them to power commercial )essels (see NS Sa+annah)' In addition to traditional fi8ed and controlla"le pitch propellers there are many speciali(ed )ariations, such as contra-rotating and no((le-style propellers' ,ost )essels ha)e a single propeller, "ut some large )essels may ha)e up to four propellers supplemented with trans)erse thrusters for maneu)ring at ports' <he propeller is connected to the main engine )ia a propeller shaft and, in case of medium- and high-speed engines, a reduction gear"o8' Some modern )essels ha)e a diesel-electric powertrain in which the propeller is turned "y an electric motor powered "y the ship7s generators'

Steerin$ syste s3edit4

<he rudder and propeller on a newly "uiltferry

For ships with independent propulsion systems for each side, such as manual oars or some paddles,3&/4 steering systems may not "e necessary' In most designs, such as "oats propelled "y engines or sails, a steering system "ecomes necessary' <he most common is a rudder, a su"merged plane located at the rear of the hull' Rudders are rotated to generate a lateral force which turns the "oat' Rudders can "e rotated "y a tiller, manual wheels, or electrohydraulic systems' 5utopilot systems com"ine mechanical

rudders with na)igation systems' =ucted propellers are sometimes used for steering' Some propulsion systems are inherently steering systems' :8amples include the out"oard motor, the "ow thruster, and the 9-dri)e'

'olds( co part ents( and the superstructure3edit4
>arger "oats and ships generally ha)e multiple decks and compartments' Separate "erthings and heads are found on sail"oats o)er a"out 2/ feet (%'& m)' Fishing "oats and cargo ships typically ha)e one or more cargo holds' ,ost larger )essels ha)e an engine room, a galley, and )arious compartments for work' <anks are used to store fuel, engine oil, and fresh water' @allast tanks are e+uipped to change a ship7s trim and modify its sta"ility' Superstructures are found a"o)e the main deck' 6n sail"oats, these are usually )ery low' 6n modern cargo ships, they are almost always located near the ship7s stern' 6n passenger ships and warships, the superstructure generally e8tends far forward'

)quip ent3edit4
Ship"oard e+uipment )aries from ship to ship depending on such factors as the ship7s era, design, area of operation, and purpose' Some types of e+uipment that are widely found includeA



,asts can "e the home of antennas, na)igation lights, radar transponders, fog signals, and similar de)ices often re+uired "y law'



Cround tackle includes e+uipment such as mooring winches, windlasses, and anchors' 5nchors are used to moor ships in shallow water' <hey are connected to the ship "y a rope or chain' 6n larger )essels, the chain runs through a hawsepipe'



-argo e+uipment such as cranes and cargo "ooms are used to load and unload cargo and ship7s stores'



Safety e+uipment such as life"oats, liferafts, and sur)i)al suits are carried a"oard many )essels for emergency use'

=esign considerations3edit4
'ydrostatics3edit4

Some )essels, like the >-5-, can operate in a nondisplacement mode'

@oats and ships are kept on (or slightly a"o)e) the water in three waysA



For most )essels, known as displacement )essels, the )essel7s weight is offset "y that of the water displaced "y the hull'



For planing ships and "oats, such as the hydrofoil, the lift de)eloped "y the mo)ement of the foil through the water increases with the )essel7s speed, until the )essel is foil"orne'



For non-displacement craft such as ho)ercraft and aircushion )ehicles, the )essel is suspended o)er the water "y a cushion of high-pressure air it proDects downwards against the surface of the water'

5 )essel is in e+uili"rium when the upwards and downwards forces are of e+ual magnitude' 5s a )essel is lowered into the water its weight remains constant "ut the corresponding weight of water displaced "y its hull increases' When the two forces are e+ual, the "oat floats' If weight is e)enly distri"uted throughout the )essel, it floats without trim or heel' 5 )essel7s sta"ility is considered in "oth this hydrostatic sense as well as a hydrodynamic sense, when su"Dected to mo)ement, rolling and pitching, and the action of wa)es and wind' Sta"ility pro"lems can lead to e8cessi)e pitching and rolling, and e)entually capsi(ing and sinking'

'ydrodyna ics3edit4

Fishing "oat !ona !elfina

<he ad)ance of a )essel through water is resisted "y the water' <his resistance can "e "roken down into se)eral components, the main ones "eing the friction of the water on the hull and wa)e making resistance' <o reduce resistance and therefore increase the speed for a gi)en power, it is necessary to reduce the wetted surface and use su"merged hull shapes that produce low amplitude wa)es' <o do so, high-speed )essels are often more slender, with fewer or smaller appendages' <he friction of the water is also reduced "y regular maintenance of the hull to remo)e the sea creatures and algae that accumulate there' 5ntifouling paint

is commonly used to assist in this' 5d)anced designs such as the "ul"ous "ow assist in decreasing wa)e resistance' 5 simple way of considering wa)e-making resistance is to look at the hull in relation to its wake' 5t speeds lower than the wa)e propagation speed, the wa)e rapidly dissipates to the sides' 5s the hull approaches the wa)e propagation speed, howe)er, the wake at the "ow "egins to "uild up faster than it can dissipate, and so it grows in amplitude' Since the water is not a"le to *get out of the way of the hull fast enough*, the hull, in essence, has to clim" o)er or push through the "ow wa)e' <his results in an e8ponential increase in resistance with increasing speed' <his hull speed is found "y the formulaA

or, in metric unitsA

where 5 is the length of the waterline in feet or meters' When the )essel e8ceeds a speedFlength ratio of 0'$1, it starts to outrun most of its "ow wa)e, and the hull actually settles slightly in the water as it is now only supported "y two wa)e peaks' 5s the )essel e8ceeds a speedFlength ratio of #'.1, the hull speed, the wa)elength is now longer than the hull, and the stern is no longer supported "y the wake, causing the stern to s+uat, and the "ow rise' <he hull is now starting to clim" its own "ow wa)e, and resistance "egins to increase at a )ery high rate' While it is possi"le to dri)e a displacement hull faster than a speedFlength ratio of #'.1, it is prohi"iti)ely e8pensi)e to do so' ,ost large )essels operate at speedFlength ratios well "elow that le)el, at speedFlength ratios of under #'0'

Gessels mo)e along the three a8esA #' hea)e, 2' sway, .' surge, 1' yaw, /' pitch, &' roll

For large proDects with ade+uate funding, hydrodynamic resistance can "e tested e8perimentally in a hull testing pool or using tools of computational fluid dynamics' Gessels are also su"Dect to ocean surface wa)es and sea swell as well as effects of wind and weather' <hese mo)ements can "e stressful for passengers and e+uipment, and must "e controlled if possi"le' <he rolling mo)ement can "e controlled, to an e8tent, "y "allasting or "y de)ices such as fin sta"ili(ers' ;itching mo)ement is more difficult to limit and can "e dangerous if the "ow su"merges in the wa)es, a phenomenon called pounding' Sometimes, ships must change course or speed to stop )iolent rolling or pitching' !ow it has "een con)incingly shown in scientific studies of the 2#st century,3&&43&%4 controlla"ility of some )essels decreases dramatically in some cases that are conditioned "y effects of the "ifurcation memory' <his class of )essels includes ships with high manoeu)ring capa"ilities, aircraft and controlled underwater )ehicles designed to "e unsta"le in steady-state motion that are interesting in terms of applications' <hese features must "e considered in designing ships and in their control in critical situations'

>ifecycle3edit4
5 ship will pass through se)eral stages during its career' <he first is usually an initial contract to "uild the ship, the details of which can )ary widely "ased on relationships "etween the shipowners, operators, designers and the shipyard'

<hen, the design phase carried out "y a na)al architect' <hen the ship is constructed in a shipyard' 5fter construction, the )essel is launched and goes into ser)ice' Ships end their careers in a num"er of ways, ranging from shipwrecks to ser)ice as a museum ship to the scrapyard'

>ines plan for the hull of a "asic cargo ship

*esi$n3edit4
See also: 0a+al architecture 5 )essel7s design starts with a specification, which a na)al architect uses to create a proDect outline, assess re+uired dimensions, and create a "asic layout of spaces and a rough displacement' 5fter this initial rough draft, the architect can create an initial hull design, a general profile and an initial o)er)iew of the ship7s propulsion' 5t this stage, the designer can iterate on the ship7s design, adding detail and refining the design at each stage' <he designer will typically produce an o)erall plan, a general specification descri"ing the peculiarities of the )essel, and construction "lueprints to "e used at the "uilding site' =esigns for larger or more comple8 )essels may also include sail plans, electrical schematics, and plum"ing and )entilation plans' 5s en)ironmental laws are strictening, ship designers need to create their design in such a way that the ship -when it nears its end-of-term- can "e disassm"ledor disposed easily and that waste is reduced to a minimum'

,S Freedom of the Seasunder construction in a shipyard in <urku'

Construction3edit4
Main article: Shipbuilding Ship construction takes place in a shipyard, and can last from a few months for a unit produced in series, to se)eral years to reconstruct a wooden "oat like the frigate :ermione, to more than #0 years for an aircraft carrier' !ull materials and )essel si(e play a large part in determining the method of construction' <he hull of a mass-produced fi"erglass sail"oat is constructed from a mold, while the steel hull of a cargo ship is made from large sections welded together as they are "uilt'

5 ship launching at the Northern Shipyard in Cdansk, ;oland

5 shipyard at Eerala, Southern India

Cenerally, construction starts with the hull, and on )essels o)er a"out .0 meters ($? ft), "y the laying of the keel' <his is done in a drydock or on land' 6nce the hull is assem"led and painted, it is launched' <he last stages, such as raising the superstructure and adding e+uipment and accommodation, can "e done after the )essel is afloat' 6nce completed, the )essel is deli)ered to the customer' Ship launching is often a ceremony of some significance, and is usually when the )essel is formally named' 5 typical small row"oat can cost under HSP#00, P#,000 for a small speed"oat, tens of thousands of dollars for a cruising sail"oat, and a"out P2,000,000 for a GendQe Clo"e class sail"oat' 5 2/ meters (?2 ft) trawler may cost P2'/ million, and a #,000-person-capacity high-speed passenger ferry can cost in the neigh"orhood of P/0 million' 5 ship7s cost partly depends on its comple8ityA a small, general cargo ship will cost P20 million, a ;anama8si(ed "ulk carrieraround P./ million, a supertanker around P#0/ million and a large >NC carrier nearly P200 million' <he most e8pensi)e ships generally are so "ecause of the cost of em"edded electronicsA a Sea$olf-class su"marine costs around P2 "illion, and an aircraft carrier goes for a"out P.'/ "illion'

Repair and con%ersion3edit4

5n a"le seaman uses a needlegun scaler while refur"ishing a mooring winch at sea

Ships undergo nearly constant maintenance during their career, whether they "e underway, pierside, or in some cases, in periods of reduced operating status "etween charters or shipping seasons' ,ost ships, howe)er, re+uire trips to special facilities such as a drydock at regular inter)als' <asks often done at drydock include remo)ing "iological growths on the hull, sand"lasting and repainting the hull, and replacing sacrificial anodes used to protect su"merged e+uipment from corrosion' ,aDor repairs to the propulsion and steering systems as well as maDor electrical systems are also often performed at dry dock' Gessels that sustain maDor damage at sea may "e repaired at a facility e+uipped for maDor repairs, such as a shipyard' Ships may also "e con)erted for a new purposeA oil tankers are often con)erted into floating production storage and offloading units'

5 ship gra)eyard in France

)nd o+ ser%ice3edit4
Main article: Ship disposal ,ost ocean-going cargo ships ha)e a life e8pectancy of "etween 20 and .0 years' 5 sail"oat made of plywood or fi"erglass can last "etween .0 and 10 years' Solid wooden ships can last much longer "ut re+uire regular maintenance' -arefully maintained steel-hulled yachts can ha)e a lifespan of o)er #00 years'

5s ships age, forces such as corrosion, osmosis, and rotting compromise hull strength, and a )essel "ecomes too dangerous to sail' 5t this point, it can "escuttled at sea or scrapped "y ship"reakers' Ships can also "e used as museum ships, or e8pended to construct "reakwaters or artificial reefs' ,any ships do not make it to the scrapyard, and are lost in fires, collisions, grounding, or sinking at sea' <here are more than . million shipwrecks on the ocean floor, the Hnited Nations estimates'3&?4 <he 5llies lost some /,#/0 ships during World War II'3&$4

,easuring ships3edit4
6ne can measure ships in terms of o)erall length, length of the ship at the waterline, "eam ("readth), depth (distance "etween the crown of the weather deck and the top of the keelson), draft(distance "etween the highest waterline and the "ottom of the ship) and tonnage' 5 num"er of different tonnage definitions e8ist and are used when descri"ing merchant ships for the purpose of tolls, ta8ation, etc' In @ritain until Samuel ;limsoll7s ,erchant Shipping 5ct of #?%&, ship-owners could load their )essels until their decks were almost awash, resulting in a dangerously unsta"le condition' 5nyone who signed on to such a ship for a )oyage and, upon reali(ing the danger, chose to lea)e the ship, could end up in Dail' ;limsoll, a ,em"er of ;arliament, realised the pro"lem and engaged someengineers to deri)e a fairly simple formula to determine the position of a line on the side of any specific ship7s hull which, when it reached the surface of the water during loading of cargo, meant the ship had reached its ma8imum safe loading le)el' <o this day, that mark, called the *;limsoll >ine*, e8ists on ships7 sides, and consists of a circle with a hori(ontal line through the centre' 6n the Creat >akes of North 5merica the circle is replaced with a diamond' @ecause different types of water

(summer, fresh, tropical fresh, winter north 5tlantic) ha)e different densities, su"se+uent regulations re+uired painting a group of lines forward of the ;limsoll mark to indicate the safe depth (or free"oard a"o)e the surface) to which a specific ship could load in water of )arious densities' !ence the *ladder* of lines seen forward of the ;limsoll mark to this day' <his is called the *free"oard mark* or *load line mark* in the marine industry'

Ship pollution3edit4
Ship pollution is the pollution of air and water "y shipping' It is a pro"lem that has "een accelerating as trade has "ecome increasingly glo"ali(ed, posing an increasing threat to the worldKs oceans and waterways as glo"ali(ation continues' It is e8pected that, R'''shipping traffic to and from the HS5 is proDected to dou"le "y 2020'*3%04 @ecause of increased traffic in ocean ports, pollution from ships also directly affects coastal areas' <he pollution produced affects "iodi)ersity, climate, food, and human health' !owe)er, the degree to which humans are polluting and how it affects the world is highly de"ated and has "een a hot international topic for the past .0 years'

,il spills3edit4
Main article: "il spill

<he .44on Valde6 spilled #0,?00,000 HS gallons (?,$$.,000 imp galB 10,??0,000 >) of oil into 5laska7s ;rince William Sound'3%#4

6il spills ha)e de)astating effects on the en)ironment' -rude oil contains polycyclic aromatic hydrocar"ons (;5!s) which are )ery difficult to clean up, and last for years in the sediment and marine en)ironment'3%24 ,arine species constantly e8posed to ;5!s can e8hi"it de)elopmental pro"lems, suscepti"ility to disease, and a"normal reproducti)e cycles' @y the sheer amount of oil carried, modern oil tankers must "e considered something of a threat to the en)ironment' 5n oil tanker can carry 2 million "arrels (.#?,000 m.) of crude oil, or ?1,000,000 HS gallons (&$,$10,000 imp galB .#?,000,000 >)' <his is more than si8 times the amount spilled in the widely known .44on Valde6 incident' In this spill, the ship ran aground and dumped #0,?00,000 HS gallons (?,$$.,000 imp galB 10,??0,000 >) of oil into the ocean in ,arch #$?$' =espite efforts of scientists, managers, and )olunteers, o)er 100,000 sea"irds, a"out #,000 sea otters, and immense num"ers of fish were killed'
3%24

<he International <anker 6wners ;ollution Federation has researched $,./# accidental spills since #$%1' 3%.4 5ccording to this study, most spills result from routine operations such as loading cargo, discharging cargo, and taking on fuel oil'
3%.4

$#L of the operational oil spills were small, resulting in

less than % tons per spill'3%.4 Spills resulting from accidents like collisions, groundings, hull failures, and e8plosions are much larger, with ?1L of these in)ol)ing losses of o)er %00 tons'3%.4 Following the .44on Valde6 spill, the Hnited States passed the 6il ;ollution 5ct of #$$0 (6;5-$0), which included a stipulation that all tankers entering its waters "e dou"lehulled "y 20#/' Following the sinkings of the .ri-a (#$$$) and 8restige (2002), the :uropean Hnion passed its own stringent anti-pollution packages (known as :rika I, II, and III), which re+uire all tankers entering its waters to "e dou"le-

hulled "y 20#0' <he :rika packages are contro)ersial "ecause they introduced the new legal concept of *serious negligence*'3%14

-allast .ater3edit4
Main article: )allast $ater discharge and the en+ironment

5 cargo ship pumps "allast water o)er the side

When a large )essel such as a container ship or an oil tanker unloads cargo, seawater is pumped into other compartments in the hull to help sta"ili(e and "alance the ship' =uring loading, this "allast water is pumped out from these compartments'3%/4 6ne of the pro"lems with "allast water transfer is the transport of harmful organisms' ,eines(3%&4 "elie)es that one of the worst cases of a single in)asi)e species causing harm to an ecosystem can "e attri"uted to a seemingly harmless Dellyfish' Mnemiopsis leidyi, a species of com" Dellyfish that inha"its estuaries from the Hnited States to the GaldQs peninsula in 5rgentina along the 5tlantic coast, has caused nota"le damage in the @lack Sea' It was first introduced in #$?2, and thought to ha)e "een transported to the @lack Sea in a shipKs "allast water' <he population of the Dellyfish shot up e8ponentially and, "y #$??, it was wreaking ha)oc upon the local fishing industry' *<he ancho)y catch fell

from 201,000 tonnes (22/,000 short tonsB 20#,000 long tons) in #$?1 to 200 tonnes (220 short tonsB #$% long tons) in #$$.B sprat from 21,&00 tonnes (2%,#00 short tonsB 21,200 long tons) in #$?1 to #2,000 tonnes (#.,200 short tonsB ##,?00 long tons) in #$$.B horse mackerel from 1,000 tonnes (1,1#0 short tonsB .,$10 long tons) in #$?1 to (ero in #$$.'*3%&4 Now that the Dellyfish ha)e e8hausted the(ooplankton, including fish lar)ae, their num"ers ha)e fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem' Recently the Dellyfish ha)e "een disco)ered in the -aspian Sea' In)asi)e species can take o)er once occupied areas, facilitate the spread of new diseases, introduce new geneticmaterial, alter landscapes and Deopardi(e the a"ility of nati)e species to o"tain food' *6n land and in the sea, in)asi)e species are responsi"le for a"out #.% "illion dollars in lost re)enue and management costs in the H'S' each year'* 3%24 @allast and "ilge discharge from ships can also spread human pathogens and other harmful diseases and to8ins potentially causing health issues for humans and marine life alike'3%%4 =ischarges into coastal waters, along with other sources of marine pollution, ha)e the potential to "e to8ic to marine plants, animals, and microorganisms, causing alterations such as changes in growth, disruption of hormone cycles, "irth defects, suppression of the immune system, and disorders resulting in cancer, tumors, and genetic a"normalities or e)en death'3%24

)/haust e issions3edit4

:8haust stack on a container ship'

:8haust emissions from ships are considered to "e a significant source of air pollution' RSeagoing )essels are responsi"le for an estimated #1 percent of emissions of nitrogen from fossil fuels and #& percent of the emissions of sulfur from petroleum uses into the atmosphere'S3%24 In :urope ships make up a large percentage of the sulfur introduced to the air, R'''as much sulfur as all the cars, lorries and factories in :urope put together'S 3%?4 R@y 20#0, up to 10L of air pollution o)er land could come from ships'S3%?4 Sulfur in the air creates acid rain which damages crops and "uildings' When inhaled sulfur is known to causerespiratory pro"lems and increase the risk of a heart attack'3%?4

Ship #rea0in$3edit4
Main article: Ship brea-ing Ship #rea0in$ or ship de olition is a type of ship disposal in)ol)ing the "reaking up of ships for scrap recycling, with the hulls "eing discarded in ship gra)eyards' ,ost ships ha)e a lifespan of a few decades "efore there is so much wear that refitting and repair "ecomes uneconomical' Ship "reaking allows materials from the ship, especially steel, to "e reused'

Ship "reaking near -hittagong,@angladesh

In addition to steel and other useful materials, howe)er, ships (particularly older )essels) can contain many su"stances that are "anned or considered dangerous

in de)eloped countries' 5s"estos and polychlorinated "iphenyls (;-@s) are typical e8amples' 5s"estos was used hea)ily in ship construction until it was finally "anned in most of the de)eloped world in the mid #$?0s' -urrently, the costs associated with remo)ing as"estos, along with the potentially e8pensi)e insurance and health risks, ha)e meant that ship"reaking in most de)eloped countries is no longer economically )ia"le' Remo)ing the metal for scrap can potentially cost more than the scrap )alue of the metal itself' In the de)eloping world, howe)er, shipyards can operate without the risk of personal inDury lawsuits or workers7 health claims, meaning many of these shipyards may operate with high health risks' ;rotecti)e e+uipment is sometimes a"sent or inade+uate' =angerous )apors and fumes from "urning materials can "e inhaled, and dusty as"estos-laden areas around such "reakdown locations are commonplace' 5side from the health of the yard workers, in recent years, ship "reaking has also "ecome an issue of maDor en)ironmental concern' ,any de)eloping nations, in which ship "reaking yards are located, ha)e la8 or no en)ironmental law, ena"ling large +uantities of highly to8ic materials to escape into the en)ironment and causing serious health pro"lems among ship "reakers, the local population and wildlife' :n)ironmental campaign groups such asCreenpeace ha)e made the issue a high priority for their campaigns'3%$4

@uoyancy3edit4
See also: )uoyancy 5 floating "oat displaces its weight in water' <he material of the "oat hull may "e denser than water, "ut if this is the case then it forms only the outer layer' If the "oat floats, the mass of the "oat (plus contents) as a $hole di)ided "y the )olume belo$ the $aterline is e+ual to the density of water (# kgFl)' If weight is added to the "oat, the )olume "elow the

waterline will increase to keep the weight "alance e+ual, and so the "oat sinks a little to compensate'

See also3edit4

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