Bulk carriers, also known as lakers or lake carriers, are a common sight on the Great Lakes. These massive ships transport taconite (iron ore pellets), cement, sand, aggregates, grain, and other commodities throughout the region.
Great Lakes bulk carriers provide an energy-efficient service for transporting bulk commodities as compared to alternatives such as trucking or rail transportation.
Great Lakes ships usually last for many years because they operate in fresh water where corrosion is less. The average lifespan of bulk carriers on the Great Lakes is approximately 40-50 years.
Throughout the Great Lakes region, bulk carriers are enthusiastically viewed and photographed by ship spotting enthusiasts.
Types of Bulk Carriers
Older Great Lakes bulk carriers were usually constructed with the bridge at the bow and a second island over the engine room in the stern. Modern vessels have a single island at the stern.
Mini-bulk carriers are designed primarily for river transport. Their size allows them to pass under bridges and manuever in tight quarters. They usually have a single hold and carry from 500 to 2,500 tons of cargo.
Gearless bulk carriers are common in the Great Lakes region. They range in size from seaway class to giants of 1000 feet in length or more. Many gearless bulk carriers have coastal and deep-sea trading capability.
Geared bulk carriers are equipped with cranes, derricks, or conveyors that allow them to load or discharge cargo in ports without specialized equipment.
Self-unloading bulk carriers are equipped to discharge their cargo without the assistance of shore-based equipment such as cranes, conveyor belts, or loaders. The discharge boom allows operators to unload cargo onto a docks, barges, or onto the ground.
Many geared bulk carriers are built specifically for use within the Great Lakes / St. Lawrence Seaway System. They typically have a snub-nosed bow and vertical sides to maximize cargo carrying capacity.
Numerous configurations of barges are also common along the Great Lakes. Traditional barges are towed or pushed by specialized vessels known as pushboats.
Articulated tug-barges (ATBs) consist of a barge and specialized tug positioned in a notch in the stern of the barge. The configuration features an articulated or “hinged” connection system between the tug and barge. ATBs are sometimes known as “pin tugs.”
Integrated tug-barge configurations consist of a tug and barge in a rigid connection that perform as one unit.
Locks on the St. Lawrence and on the Welland Canal are 766 ft (233.5 m) long, 80 ft (24.4 m) wide, and 30 ft (9.14 m) deep. The maximum allowed vessel size is slightly smaller: 740 ft (225.6 m) long, 78 ft (23.8 m) wide, and 26.5 ft (8.1 m) deep.
Many vessels designed for use on the Great Lakes following the opening of the seaway were built to the maximum size permissible by the locks, known informally as Seawaymax or Seaway-Max.
Large vessels of the lake freighter fleet are built on the lakes and cannot travel downstream beyond the Welland Canal.
On the remaining Great Lakes, these ships are constrained only by the largest lock on the Great Lakes Waterway, the Poe Lock at the Soo Locks (at Sault Ste. Marie), which is 1,200 ft (365.8 m) long, 110 ft (33.5 m) wide and 32 ft (9.8 m) deep.
The largest ship on the Great Lakes is the 1,014 feet long and 105 feet wide self-unloading bulk carrier Paul R. Tregurtha.
Bulk Carrier Sizes
Mini: Capacity of less than 10,000 DWT (dead weight tonnage).
Small: 10,000 to 25,000 DWT capacity.
Handysize: 25,000 to 40,000 DWT capacity.
Handymax: 40,000 to 50,000 DWT capacity.
Supramax: 50,000 to 60,000 DWT capacity.
Panamax: 60,000 to 80,000 DWT capacity.
Capesize: 80,000 DWT capacity.
Seawaymax: vessel dimensions not greater than 740 ft (225.6 m) long, 78 ft (23.8 m) wide, and 26.5 ft (8.1 m) deep.
Maritime Acronyms
ATB – articulated tug-barge
BOL: Bill of Lading
ITB – integrated tug/barge
LCA – Lake Carriers’ Association
OBO – Ore-Bulk-Oil carrier
O/O – Oil/Ore carrier