What is a Heavy Load Carrier?

There are several ways to ship large and heavy loads. Many heavy or oversized items can be shipped by air, ground, or sea. But when it comes to extremely large and heavy items that need to be shipped overseas, the only option is a specialized type of ship called a heavy load carrier (also called a heavy lift ship).

These massive ships can handle loads that are too heavy for planes and could damage the structural integrity of conventional boats.

These ships are some of the largest vessels in the world, measuring as much as 1300 feet long and 200 feet wide. They can transport cumbersome items like construction and mining equipment, industrial machinery, and other ships.

Types of Heavy Load Carriers

There are four main types of heavy lift vessels:

Semi-Submersible Vessels

These ships use ballast water tanks to take on water intentionally. This lowers the boat more deeply into the water until the upper deck is submerged a few meters below the water's surface.

This is done so that goods can be loaded onto the submerged deck by floating them directly over their intended space on the deck. Once correctly positioned, the ballast water is pumped out until the vessel's deck rises above the water for a safe voyage.

Dock Ships

Dock ships are similar to semi-submersibles in design and function, but they use large side panels on the port and starboard to act as reservoirs for ballast water. This allows dock ships to lower their upper decks into the water so cargo can be floated onto the boat before the ballast water is released and it lifts back up to prepare for passage.

The primary type of cargo dock ships carry is other ships for transport or repair. Dock ships are handy for repairing vessels that cannot move or get to dry docks. Repairs can be made to vessels while on the dock ship, so they can even serve as an alternative to dry docks entirely.

Open-Deck Cargo Ships

Unlike semi-submersibles and dock ships, open-deck ships don't require their heavy cargo to be floated into position on deck. Open-deck cargo can be placed on the vessel using cranes on the deck or driven onto it using roll-on-roll-off methods (these are also known as ro-ro carriers).

Because open-deck ships have no deck walls, they export cargo wider than the ship itself; these heavy lift vessels are handy for transporting cranes, construction equipment, large trucks, yachts, and small boats.

Project Cargo Carriers

Project cargo carriers are highly-specialized heavy lift vessels that can carry heavy and oversized, high-value cargo called "project cargo," which is often critical for some industries. This cargo can include pipelines, bridge and crane sections, and sections of industrial units.

Unlike ro-ro carriers, project cargo ships are not designed for wheeled cargo and cannot be floated onboard. Instead, they are equipped with one or more cranes capable of lifting this special, heavy cargo on and off the vessel. Most port facilities don't have cranes to handle project cargo loads, so project cargo carriers don't have to rely on terminal equipment as other heavy-load vessels do.

Project cargo carriers are typically smaller than other heavy-lifting vessels, but they still have the ship design to carry hefty loads.

Types of Heavy Loads

Heavy-lift vessels handle a large variety of cargo. Here are some of the main categories of equipment and machinery that require special heavy-load carriers for proper cargo care during maritime transport:

• Construction Equipment: This includes bulldozers, loaders, cranes, excavators, and concrete mixers.
• Agricultural Equipment: Heavy machinery like tractors, combines, harvesters, and other farm equipment require a cargo capacity larger than regular ships can provide.
• Industrial Machinery: This encompasses various heavy machinery used in manufacturing processes in industrial plants.
• Mining Equipment: Mining operations often use large and heavy equipment, such as drill rigs, dragline excavators, and haul trucks.
• Specialized Equipment: Some types of overweight equipment are specialized, like dredging equipment or equipment for infrastructure or military purposes that conventional ships can't handle.

Heavy Load Carriers vs. Container Ships and Bulk Carrier Ships

It might be easy to picture a container ship while discussing heavy-lifting vessels. Containers (box ships) are among the most significant vessels coming and going from most ports. They have a high load capacity compared to regular ships; they are incapable of the safe maritime transport of bulky cargo that heavy-load carriers can provide.

Container ships are cargo ships that transport the vast majority of non-bulk cargo worldwide in standard-sized, stackable containers. Because they are widely used in international transport, container ships are usually highly automated, and newer models can emit zero emissions.

Meanwhile, bulk carrier ships are specially designed to transport raw materials like iron ore, coal, and grain, although combination carriers can also carry liquid cargo like gas and oil.

The bulk carrier fleet is divided into six major categories based on cargo capacity. These classes are:

• Small-Sized Ships (mostly made up of single-hold mini-bulk carriers)
• Handysize Ships
• Handymax Ships
• Panamax Ships
• Capesize Ships
• Very Large Carriers

Large carriers technically fall into the Capesize category but are generally considered separately. Huge and Capesize ships that travel between the Pacific and Atlantic oceans are too large to traverse the Panama Canal, so they are forced to round Cape Horn on these routes. Some mammoth ore ships can carry up to 400,000 metric tons of cargo.

After World War II, there was a significant increase in international bulk trade, especially between the United States, European countries, and Japan. This resulted in the bulk carrier fleet building larger ocean bulk carriers to meet international shipping demand. While these are impressive carriers, the average design ship speed for huge and Capesize ships is not fast. They have a relatively low fixed-pitch propeller speed and travel at a max speed of about 14.5 knots.

Although there were some tragic bulk carrier sinkings in the 1990s, partly due to outdated and overused ships, today's bulk carrier fleet is subject to many international measures to keep carrier crews and the entire boat safe and ensure proper cargo care. The thorough safety assessment of bulk carriers has never been more robust, with systems like high-level water alarms becoming mandatory on all bulk carriers.

Advanced Technology

The days of only older steam-powered ships for maritime transport are over. The maritime transport industry now includes several different types of marine engines for propulsion. The most common propulsion systems for large ships are diesel or bunker fuel (also known as heavy fuel oil).

But steamships still represent a portion of the maritime transport fleet. Liquified natural gas (LNG) ships have marine engines that use steam turbines powered by high-pressure boilers to power their propellers. Many steamship boilers can run on various fuels, including natural gas, diesel, heavy fuel oil, or coal.

Advanced port technology, improved shipping and terminal logistics, and modern cargo loading operations also add a technological advantage to carriers of all types by minimizing port time while taking care of safety.

Conclusion

Heavy-load carriers play a crucial role in today's ever-growing international shipping demand. With specialized designs for an entire ship, carrier crews move equipment and machinery overseas that once seemed impossible. And with the oversight of the International Maritime Organization, safety will remain a top priority along with cargo care.

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