![Ballast tank boat cross section](https://upload.wikimedia.org/wikipedia/commons/b/b9/Ballast_tank_boat_cross_section.png)
Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than
cargo
Cargo consists of bulk goods conveyed by water, air, or land. In economics, freight is cargo that is transported at a freight rate for commercial gain. ''Cargo'' was originally a shipload but now covers all types of freight, including trans ...
, may be placed in a vehicle, often a
ship
A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...
or the
gondola
The gondola (, ; vec, góndoła ) is a traditional, flat-bottomed Venetian rowing boat, well suited to the conditions of the Venetian lagoon. It is typically propelled by a gondolier, who uses a rowing oar, which is not fastened to the hull ...
of a
balloon
A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air. For special tasks, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), or light so ...
or
airship
An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air.
In early ...
, to provide
stability
Stability may refer to:
Mathematics
*Stability theory, the study of the stability of solutions to differential equations and dynamical systems
**Asymptotic stability
**Linear stability
**Lyapunov stability
**Orbital stability
**Structural stabilit ...
. A compartment within a boat, ship,
submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
, or other floating structure that holds water is called a
ballast tank
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, ...
. Water should move in and out from the ballast tank to balance the ship. In a vessel that travels on the water, the ballast will remain below the water level, to counteract the effects of weight above the water level. The ballast may be redistributed in the vessel or disposed of altogether to change its effects on the movement of the vessel.
History
The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the
blowfish
Tetraodontidae is a family of primarily marine and estuarine fish of the order Tetraodontiformes. The family includes many familiar species variously called pufferfish, puffers, balloonfish, blowfish, blowies, bubblefish, globefish, swellfis ...
or members of the
argonaut
The Argonauts (; Ancient Greek: ) were a band of heroes in Greek mythology, who in the years before the Trojan War (around 1300 BC) accompanied Jason to Colchis in his quest to find the Golden Fleece. Their name comes from their ship, ''Argo'', ...
group of
octopus
An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...
. The concept has been invented and reinvented many times by humans to serve a variety of purposes.
In the fifteenth and sixteenth century, the ballast "did not consist entirely of leakage, but of urine, vomit, and various foul food leavings that lazy sailors discharged into the ballast contrary to orders, in the belief that the pumps would take care of it." In the nineteenth century, cargo boats returning from Europe to North America would carry quarried stone as ballast, contributing to the architectural heritage of some east coast cities (for example
Montreal
Montreal ( ; officially Montréal, ) is the List of the largest municipalities in Canada by population, second-most populous city in Canada and List of towns in Quebec, most populous city in the Provinces and territories of Canada, Canadian ...
), where this stone was used in building.
During
World War 2
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
ships returning from Great Britain to America used rubble as ballast. The ballast would be dumped in New York and used for construction projects such as
FDR Drive
The Franklin D. Roosevelt East River Drive, commonly called the FDR Drive for short, is a limited-access parkway on the east side of the New York City borough of Manhattan. It starts near South and Broad Streets, just north of the Battery Park ...
and an outcrop colloquially named Bristol Basin since it was made from rubble from bombed-out
Bristol
Bristol () is a city, ceremonial county and unitary authority in England. Situated on the River Avon, it is bordered by the ceremonial counties of Gloucestershire to the north and Somerset to the south. Bristol is the most populous city in ...
.
Uses
![Yacht keel](https://upload.wikimedia.org/wikipedia/commons/7/7c/Yacht_keel.svg)
Ballast takes many forms. The simplest form of ballast used in small
day sailer
A daysailer, day sailer, or dayboat is a small sailboat with or without sleeping accommodations but which is larger than a dinghy. Dayboats can be mono hull or multihull, and are typically trailer-able. Many dayboats have a small cabin or "cu ...
s is so-called "live ballast", or the weight of the crew. By sitting on the
windward
Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
side of the
hull, the
heeling moment
Forces on sails result from movement of air that interacts with sails and gives them motive power for sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and sail-powered land vehicles. Similar principles in a rotating f ...
must lift the weight of the crew. On more advanced racing boats, a wire harness called a
trapeze
A trapeze is a short horizontal bar hung by ropes or metal straps from a ceiling support. It is an aerial apparatus commonly found in circus performances. Trapeze acts may be static, spinning (rigged from a single point), swinging or flying, an ...
is used to allow the crew to hang completely over the side of the hull without falling out; this provides much larger amounts of
righting moment
The metacentric height (GM) is a measurement of the initial static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre. A larger metacentric height implies greater initial stab ...
due to the larger
lever
A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or ''fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is div ...
age of the crew's weight, but can be dangerous if the wind suddenly dies, as the sudden loss of heeling moment can dump the crew in the water. On larger modern vessels, the
keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
is made of or filled with a high
density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
material, such as
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
,
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
, or
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
. By placing the weight as low as possible (often in a large bulb at the bottom of the keel) the maximum righting moment can be extracted from the given mass. Traditional forms of ballast carried inside the hull were stones or sand.
Sailing ballast
Ballast is used in ships to provide moment to resist the lateral forces on the hull. Insufficiently ballasted boats tend to tip or heel excessively in high winds. Too much heel may result in the vessel capsizing. If a sailing vessel needs to vo ...
is used in
sailboats
A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.
Types
Although sailboat terminology ...
to provide
moment
Moment or Moments may refer to:
* Present time
Music
* The Moments, American R&B vocal group Albums
* ''Moment'' (Dark Tranquillity album), 2020
* ''Moment'' (Speed album), 1998
* ''Moments'' (Darude album)
* ''Moments'' (Christine Guldbrand ...
to resist the lateral forces on the
sail
A sail is a tensile structure—which is made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may ...
. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds. Too much heel may result in the boat
capsizing
Capsizing or keeling over occurs when a boat or ship is rolled on its side or further by wave action, instability or wind force beyond the angle of positive static stability or it is upside down in the water. The act of recovering a vessel fro ...
. If a sailing vessel should need to voyage without cargo then ballast of little or no value would be loaded to keep the vessel upright. Some or all of this ballast would then be discarded when cargo was loaded.
Ballast weight
Ballast weight is something that is added to a race car to alter its performance.
In most racing series, cars have a minimum weight. Often, the actual weight of the car is lower, so ballast is used to bring it up to the minimum. The advantage i ...
is also added to a
race car
Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport involving the racing of automobiles for competition.
Auto racing has existed since the invention of the automobile. Races of various sorts were organi ...
to alter its performance. In most racing series, cars have a minimum allowable weight. Often, the actual weight of the car is lower, so ballast is used to bring it up to the minimum. The advantage is that the ballast can be positioned to affect the car's handling by changing its
load distribution
In computing, load balancing is the process of distributing a set of tasks over a set of resources (computing units), with the aim of making their overall processing more efficient. Load balancing can optimize the response time and avoid unevenl ...
. This is near-universal in
Formula 1
Formula One (also known as Formula 1 or F1) is the highest class of international racing for open-wheel single-seater formula racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The World Drivers' Championship, ...
. It is also common in other racing series that ballast may only be located in certain positions on the car. In some racing series, for example the
British Touring Car Championship
The Kwik Fit British Touring Car Championship is a touring car racing series held each year in the United Kingdom, currently organised and administered by TOCA
TOCA, formally trading as BARC (TOCA) Ltd, is an organiser of motorsport events in ...
, ballast is used as a handicap, the leading drivers at the end of one race being given more ballast for the next race.
Ballast may also be carried aboard an aircraft. For example, in
gliding
Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word ''soaring'' is al ...
it may be used to increase speed and/or adjust the aircraft's center of gravity, or in a balloon as a
buoyancy compensator.
In commercial shipping
If a cargo vessel (such as a tanker, bulk carrier or container ship) wishes to travel empty or partially empty to collect a cargo, it must travel ''in
ballast
Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, ...
''. This keeps the vessel in trim and keeps the propeller and rudder submerged. Typically, being "in ballast" will mean flooding the ballast tanks with sea water. Serious problems arise
when the ballast water is discharged, as water-borne organisms may create havoc when deposited in new environments.
In railways
Not all types of railway tracks use ballast.
[Tubular Modular Track]
References
Sources
* {{cite book , title=Railway Maintenance Equipment: The Men and Machines that Keep the Railroads Running , last=Solomon , first=Brian , publisher=MBI Publishing Company , year=2001 , isbn=0-7603-0975-2
Mechanisms (engineering)
Watercraft components