
Slave ships were large
cargo ship
A cargo ship or freighter is a merchant ship that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's List of seas, seas and Ocean, oceans each year, handling the bulk of international trade. ...
s specially built or converted from the 17th to the 19th century for transporting
slaves
Slavery is the ownership of a person as property, especially in regards to their labour. Slavery typically involves compulsory work, with the slave's location of work and residence dictated by the party that holds them in bondage. Enslavemen ...
. Such ships were also known as "Guineamen" because the trade involved human trafficking to and from the
Guinea coast in West Africa.
Atlantic slave trade
In the early 17th century, more than a century after the arrival of
Europeans
Europeans are the focus of European ethnology, the field of anthropology related to the various ethnic groups that reside in the states of Europe. Groups may be defined by common ancestry, language, faith, historical continuity, etc. There are ...
to the
Americas
The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...
, demand for unpaid labor to work plantations made slave-trading a profitable business. The
Atlantic slave trade
The Atlantic slave trade or transatlantic slave trade involved the transportation by slave traders of Slavery in Africa, enslaved African people to the Americas. European slave ships regularly used the triangular trade route and its Middle Pass ...
peaked in the last two decades of the 18th century, during and following the
Kongo Civil War
The Kongo Civil War (1665–1709) was a war of succession between rival houses of the Kingdom of Kongo. The war waged throughout the middle of the 17th and 18th centuries pitting partisans of the House of Kinlaza against the House of Kimpanzu. ...
.
To ensure
profitability
In economics, profit is the difference between revenue that an economic entity has received from its outputs and total costs of its inputs, also known as surplus value. It is equal to total revenue minus total cost, including both Explicit co ...
, the owners of the ships divided their
hulls into holds with little headroom, so they could transport as many slaves as possible. Unhygienic conditions,
dehydration
In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...
,
dysentery
Dysentery ( , ), historically known as the bloody flux, is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications may include dehyd ...
, and
scurvy
Scurvy is a deficiency disease (state of malnutrition) resulting from a lack of vitamin C (ascorbic acid). Early symptoms of deficiency include weakness, fatigue, and sore arms and legs. Without treatment, anemia, decreased red blood cells, gum d ...
led to a high
mortality rate
Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular Statistical population, population, scaled to the size of that population, per unit of time. Mortality rate is typically ...
, on average 15% and up to a third of captives. Often, the ships carried hundreds of slaves, who were chained tightly to plank beds. For example, the slave ship ''Henrietta Marie'' carried about 200 slaves on the long
Middle Passage
The Middle Passage was the stage of the Atlantic slave trade in which millions of Africans sold for enslavement were forcibly transported to the Americas as part of the triangular slave trade. Ships departed Europe for African markets with manu ...
. They were confined to cargo holds, with each slave chained with little room to move.
The most significant routes of the slave ships led from the north-western and western coasts of Africa to South America and the south-east coast of what is today the United States, and the
Caribbean
The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
. As many as 20 million Africans were transported by ship.
The transportation of slaves from Africa to the Americas was known as the Middle Passage of the
triangular trade
Triangular trade or triangle trade is trade between three ports or regions. Triangular trade usually evolves when a region has export commodities that are not required in the region from which its major imports come. It has been used to offset ...
.
Conditions on slave ships
Slaves

The owners of slave ships embarked as many slaves as possible to make the voyage more profitable. They did so by cramming, chaining, and selectively grouping slaves to maximize the use of space. Slaves began to die of lack of oxygen due to these cramped conditions. Portuguese lawmakers passed the Tonnage Act of 1684 in order to slightly improve conditions. Slaves on board were underfed and brutally treated, causing many to die before even arriving at their destination; dead or dying slaves were dumped overboard. An average of one to two months was needed to complete the journey. The slaves were naked and shackled together with several different types of chains, stored on the floor beneath bunks with little to no room to move. Some captains assigned slave guardians to watch over and keep the other slaves in check. They spent a large portion of time pinned to floorboards, which would wear skin on their elbows down to the bone. Diseases such as
dysentery
Dysentery ( , ), historically known as the bloody flux, is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications may include dehyd ...
,
diarrhea
Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...
,
ophthalmoparesis,
malaria
Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...
, smallpox, yellow fever, scurvy, measles, typhoid fever, hookworm, tapeworm, sleeping sickness,
trypanosomiasis, yaws, syphilis, leprosy, elephantiasis, and
melancholia
Melancholia or melancholy (from ',Burton, Bk. I, p. 147 meaning black bile) is a concept found throughout ancient, medieval, and premodern medicine in Europe that describes a condition characterized by markedly depressed mood, bodily complain ...
resulted in the deaths of slaves on board slave ships. Firsthand accounts from former slaves, such as
Olaudah Equiano, describe the horrific conditions that slaves were forced to endure.
The
Slave Trade Act 1788, also known as Dolben's Act, regulated conditions on board British slave ships for the first time since the slave trade started. It was introduced to the United Kingdom Parliament by
Sir William Dolben, an advocate for the abolition of slavery. For the first time, limits were placed on the number of slaves that could be carried. Under the terms of the act, ships could transport 1.67 slaves per ton up to a maximum of 207 tons burthen, after which only one slave per ton could be carried. The well-known slave ship ''
Brookes'' was limited to carrying 454 people; it had previously transported as many as 609 enslaved.
Olaudah Equiano was among the supporters of the act, but it was opposed by some abolitionists, such as
William Wilberforce
William Wilberforce (24 August 1759 – 29 July 1833) was a British politician, philanthropist, and a leader of the movement to abolish the Atlantic slave trade. A native of Kingston upon Hull, Yorkshire, he began his political career in 1780 ...
, who feared it would establish the idea that the slave trade simply needed reform and regulation, rather than complete abolition.
[Hochschild 2005, p. 140.] Slave counts can also be estimated by deck area rather than registered tonnage, which results in a lower number of errors and only 6% deviation from reported figures.
This limited reduction in the overcrowding on slave ships may have reduced the on-board death rate, but this is disputed by some historians.
Sailors and crew
In the 18th and early 19th centuries, the sailors on slave ships were often poorly paid and subject to brutal discipline and treatment.
Furthermore, a crew mortality rate of around 20% was expected during a voyage, with sailors dying as a result of disease, flogging, or slave uprisings.
While conditions for the crew were far better than those of the slaves, they remained harsh and contributed to a high death rate. Sailors often had to live and sleep without shelter on the open deck for the entirety of the Atlantic voyage, as the space below deck was occupied by slaves.
Disease, specifically malaria and yellow fever, was the most common cause of death among sailors. A high crew mortality rate on the return voyage was in the captain's interests, as it reduced the number of sailors who had to be paid on reaching the home port.
[Hochschild 2005, p. 94] Crew members who survived were frequently cheated out of their wages on their return.
[Hochschild 2005, p. 114]
These aspects of the slave trade were widely known; the notoriety of slave ships amongst sailors meant those joining slave ship crews did so through coercion or because they could find no other employment. This was often the case for sailors who had spent time in prison.
[Rediker 2007, p.138]
Black sailors are known to have been among the crews of British slave ships. These men came from Africa or the Caribbean, or were British-born. Dozens of individuals have been identified by researchers from surviving records. Knowledge of this is incomplete, though, as many captains did not record the ethnicity of crew members in their ship's
muster roll. African men (and occasionally African women) also served as translators.
Abolition of the slave trade
The
African slave trade
Slavery has historically been widespread in Africa. Systems of servitude and slavery were once commonplace in parts of Africa, as they were in much of the rest of the ancient and medieval world. When the trans-Saharan slave trade, Red Sea s ...
was outlawed by the United States and the United Kingdom in 1807. The 1807
Abolition of the Slave Trade Act outlawed the slave trade throughout the
British Empire
The British Empire comprised the dominions, Crown colony, colonies, protectorates, League of Nations mandate, mandates, and other Dependent territory, territories ruled or administered by the United Kingdom and its predecessor states. It bega ...
. The
U.S. law took effect on 1 January 1808. After that date, all U.S. and British slave ships leaving Africa were seen by the law as
pirate
Piracy is an act of robbery or criminal violence by ship or boat-borne attackers upon another ship or a coastal area, typically with the goal of stealing cargo and valuable goods, or taking hostages. Those who conduct acts of piracy are call ...
vessels subject to capture by the
U.S. Navy or
Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...
. In 1815, at the
Council of Vienna, Spain, Portugal, France, and the Netherlands also agreed to abolish their slave trade. The trade did not end on legal abolition; between 1807 and 1860 British vessels captured 1,600 slave ships and freed 160,000 slaves.
After abolition, slave ships adopted quicker, more maneuverable forms to evade capture by naval warships, one favorite form being the
Baltimore Clipper. Some had hulls fitted with
copper sheathing, which significantly increased speed by preventing the growth of marine weed on the hull, which would otherwise cause drag.
This was very expensive, and at the time was only commonly fitted to Royal Navy vessels. The speed of slave ships made them attractive ships to repurpose for piracy, and also made them attractive for naval use after capture; and were examples of such vessels. HMS ''Black Joke'' had a notable career in Royal Navy service and was responsible for capturing a number of slave ships and freeing many hundreds of slaves.
Attempts have been made by descendants of African slaves to sue
Lloyd's of London
Lloyd's of London, generally known simply as Lloyd's, is a insurance and reinsurance market located in London, England. Unlike most of its competitors in the industry, it is not an insurance company; rather, Lloyd's is a corporate body gover ...
for playing a key role in
underwriting insurance policies taken out on slave ships bringing slaves from Africa to the Americas.
See also
* ''
Biography and the Black Atlantic''
*
List of slave ships
*
Slave Coast,
Gorée ("Slave island")
*
Slave ship revolts
*
Slave Trade Acts
References
Further reading
*
*
*
*
*
External links
Paper on German Transatlantic trade, including list of slave ships(in German)
Report of the Brown University Steering Committee on Slavery and JusticeUNESCO — The Slave RouteVoyages — The Trans-Atlantic Slave Trade DatabaseSlave Ships and the Middle PassageThe Slave TradeBristol UK Slave Ship Muster Roles
{{Authority control
Ship types