Why does the sea need laws?
A ship carries people and goods across water that no single country owns. If every country had different rules, ships would be unsafe and confusing. So countries agree on treaties (also called conventions). Most are made at the IMO (International Maritime Organization), a United Nations agency, and the ILO (International Labour Organization) for working conditions.
A treaty only works when each country copies it into its own national law. Then ship officers, owners and inspectors can be punished or fined under that law. The country whose flag the ship flies is called the flag state. The country whose port the ship visits is the port state, and it can inspect the ship.
Laws on seafarers
A seafarer is anyone who works on a ship. Two big treaties protect them.
- STCW (Standards of Training, Certification and Watchkeeping): sets the training a sailor or officer must have and the certificate they must hold. It also sets rules for keeping a safe watch.
- MLC 2006 (Maritime Labour Convention): the seafarers' bill of rights. It asks for a written work agreement, fair pay, medical care, decent food and rooms, and enough rest. The minimum rest is 10 hours in any 24 hours and 77 hours in any 7 days.
Countries add their own acts. For example, Japan has a Seafarers Act and a law for licensing ship officers, and India has its Merchant Shipping Act. A ship that breaks them can be stopped in port.
Laws on ship safety
After the Titanic sank in 1912, countries made SOLAS (Safety of Life at Sea). It says how a ship must be built, what lifesaving and fire-fighting equipment it must carry, and how radios and navigation aids must work.
- Load Line rules: a painted mark on the hull shows the deepest safe draft. If the mark goes under the water, the ship is overloaded.
- COLREGs: the rules for avoiding collisions, such as lights, signals and who gives way.
- Surveys and certificates: a ship is inspected often and gets certificates. In port, Port State Control inspectors can check them.
Laws on marine pollution and disaster prevention
MARPOL stops pollution from ships. It has six parts called Annexes: (I) oil, (II) harmful liquids carried in bulk, (III) packaged harmful goods, (IV) sewage, (V) garbage, (VI) air pollution from engines. Oily water from the engine room may be discharged only after an oily-water separator cleans it to 15 parts per million (15 ppm) or less.
Other rules cover ballast water (so that sea creatures are not carried to new seas), plans for oil spills, and rescue and salvage after an accident. Disaster prevention means being ready: drills, alarms, lifesaving gear, and a plan for fire, flooding or abandoning the ship.
Laws on ship hygiene
Crew live and eat on board for weeks, so clean conditions matter. The rules ask for safe drinking water, clean and covered food stores, a clean galley, safe waste disposal, pest control (rats and insects), and clean rooms. The MLC covers food and living quarters, and the WHO International Health Regulations ask ships to prove that they are sanitary. A port may check the ship and, if someone is ill, keep the ship apart (quarantine) so that disease does not spread ashore.
Public international law of the sea
Public international law is the set of rules between countries. For the sea, the main treaty is UNCLOS (UN Convention on the Law of the Sea, 1982). It divides the sea by distance from the coast (1 nautical mile = 1.852 km):
- Territorial sea: up to 12 nm (about 22 km). The coastal state's law applies, but ships of others may pass peacefully (innocent passage).
- Contiguous zone: up to 24 nm. The coastal state may check customs, health and immigration.
- Exclusive economic zone (EEZ): up to 200 nm (about 370 km). The coastal state owns the fish, oil and wind energy, but ships and aircraft may still pass.
- High seas: beyond. Every country may sail, fish and fly there. The flag state controls its own ship.
Try it: read the zones
In the 3D, tap Sea zones, then slide the ship away from the coast. Stop at 10 nm, 20 nm, 100 nm and 300 nm. Before you read the caption, guess the zone. Then check yourself. Next time you see a ship at a port, ask: which country is its flag state?
Key formulas and definitions
- 1 nautical mile = 1.852 km
- Territorial sea 12 nm = 22.2 km
- EEZ 200 nm = 370.4 km
- Oil in discharged water: 15 ppm or less (MARPOL)
- Rest: at least 10 h in 24 h and 77 h in 7 days (MLC)
Worked examples
1. A ship is 15 nm from the coast. Which zone is it in?
Territorial sea ends at 12 nm and the contiguous zone ends at 24 nm. 15 nm is between them, so it is in the contiguous zone.
2. Convert 200 nm to kilometres.
200 x 1.852 = 370.4 km. This is the outer edge of the EEZ.
3. A sailor worked 14 hours and then rested 8 hours in a day. Is this allowed under MLC rest rules?
In 24 hours he rested only 8 hours. The minimum is 10 hours, so the rest is too short. This breaks the rule.
4. Engine-room water holds 40 ppm oil. May it be pumped into the sea?
No. The limit is 15 ppm. It must go through the oily-water separator again or be kept in a tank.
5. Which treaty covers lifeboats and fire-fighting gear: STCW, SOLAS or MARPOL?
SOLAS. STCW is about crew training and MARPOL is about pollution.
Common mistakes
- Mixing up the treaties: STCW is training, MLC is working conditions, SOLAS is safety, MARPOL is pollution.
- Thinking the EEZ is the high seas. In the EEZ the coastal state controls fish and resources.
- Thinking a treaty works by itself. It becomes enforceable only through national law.
- Reading 1 nm as 1 km. A nautical mile is 1.852 km.