Sea cargo reference
Coaster
Short-sea work, and rivers where a deep-sea ship cannot go. The notes below cover the cargo, the way the hull is arranged, and the limit that puts a ship in this class.
- Typical deadweight
- Typically under 10,000 DWT
- Length overall
- Commonly under 120 m
- The limit that names it
- Shallow-draft ports, rivers and canal systems
- Ship's gear
- Geared
- Usual trade
- Short-sea and regional
- Cargo holds
- Commonly 5 or fewer
Names such as Handysize, Supramax and Capesize are market habits, not a written standard. Brokers, exchanges and owners do not all use the same deadweight band. Canal and berth limits below are published figures and stay fixed. The deadweight ranges are a guide.
Coasters
The smallest ships in the dry cargo trades. They are built for short-sea and river-sea work, not for ocean crossings.
Their value is access. A shallow draft, a modest length, and often a wheelhouse that can be lowered and masts that fold, let them reach inland river ports, canals and small harbours that no ocean-going ship could enter.
Many are ice-strengthened for Baltic and northern European winter trading. They usually carry their own gear, because the ports they serve rarely have cranes.
Cargo on board
How the hull is arranged
- One deck, with large holds closed by steel hatch covers that roll or fold aside for grabs and conveyors.
- Ballast sits in the double bottom and in the topside and hopper tanks. Those tanks also shape the hold so the cargo trims itself as it settles.
- Corrugated bulkheads stand between the holds. They take the push of a dense cargo without extra frames inside the space.
- Engine and accommodation sit aft, so the forward length stays free for cargo.
- Geared ships carry deck cranes or derricks between the hatches and can work where the port has no gear of its own.
Why this trade uses it
- A dry commodity moves with no bags, boxes or lashings, which keeps the cost per tonne low.
- Where the shore gear is good, grabs, conveyors and shiploaders shift thousands of tonnes an hour.
- A geared ship can call at ports that have no cranes.
- Holds can take several parcels of different commodities on one voyage.
Settle these points before you fix
- Iron ore and other dense cargoes load the hull hard. The loading order is strict, so the ship is not overstressed.
- Some concentrates and fines can turn liquid. They have to be checked against the transportable moisture limit before loading.
- Draft and air draft decide which berths and waterways the ship can use. Both shift with the season and the fresh-water allowance.