Not too long ago, a “heavy-lift” cargo referred to a piece weighing as much as 100 tons.
Today, the reference can allude to a single piece of cargo weighing 400 tons or more, said Alberto Mejia, director of marketing at New Orleans-based Intermarine.
“All of a sudden almost any ship can handle 400 to 500 tons,” Mejia said. “And then you have the super heavy-lift ships of 1,600 or 1,800 tons.”
What is driving up lift capacities? Several factors, it turns out. First, contractors that build refineries, coal mines and petrochemical and power plants can lower their construction costs by cutting back on their on-site construction.
And because project sites often are extremely remote; fewer voyages and less on-site construction add up to millions of dollars in cost savings. This is made possible by the ability to ship larger modules; two 1,000-ton modules are generally cheaper to transport than five 200-ton modules. Larger modules built at the fabrication plant mean less construction in a Brazilian or Indonesian jungle, an Australian desert, or a Siberian outpost.
Pre-fabricating reduces risk, Mejia said. “You have one move rather than two or three. The fewer pieces you have, the less risk you have.”
There’s also this: Project cargo is growing in size because ships are able to carry it. When shippers ask for heavier lift capacity, carriers comply to secure the business. Other carriers jump on the bandwagon, shippers build cargo even heavier, and carriers perpetuate the cycle with new ships to fit.
Gary Strom, global logistics chartering manager at Bechtel, has been watching heavy-lift’s evolution from the carrier perspective as well as the engineering, procurement and construction side since the 1970s. Even four decades ago, he said, engineers were tinkering with modularization. Modules would have gone bigger long ago, in his opinion, if vessels capable of transporting them safely had been available.
“If you are designing a facility — and large modules are like a pre-built facility — and you put it on a vessel and it rolls at sea, a 10- or 20- or 30-degree roll, then you are putting forces on a building that it perhaps wasn’t designed to endure. Imagine a 16-story office building at a 30-degree angle. It can’t hold,” Strom said.
Modules could grow to today’s massive sizes only after carriers developed sophisticated ballasting systems, abilities to load and discharge heavy cargo, and other advances that make moving such gigantic pieces possible.
Since the cost of building purpose-built vessels capable of moving huge modules is high, which came first, the cargo or the vessel to carry it? Early on, the situation resembled a cat-and-mouse game between shippers and carriers, Strom said. Carriers built heavy-lift ships, then shippers built bigger cargo. Shippers didn’t want to build cargo that couldn’t be moved; carriers didn’t want to build ships with unused capacity.
Today, the question appears to be resolved: Bigger is better. Four-hundred-ton lifts are routine for heavy-lift vessels. An assortment of super heavy-lift/heavy-load vessels are capable of lifting, rolling or floating onboard much heavier and/or extremely voluminous cargo.
Some ships can handle multiple tasks, capable of rolling, floating or lifting cargo, while others concentrate on one or two modes only. Some 8,000-deadweight-ton vessels can roll on a 4,000-ton piece of project cargo, Strom said. “They don’t have to have that lift capacity to take that heavy weight. Stern ramps can take as much as 1,600 tons at any one time. As the module is rolling onboard, you don’t have the full weight on the ramp. Some of the weight is on the dock, some on the ramp, some on the ship.”
All these modes create additional choices for shippers, Strom said. Often, cargo can either be picked up or rolled on; either method would be fine. “The cargo has to be rolled to the ship anyway. It can just keep rolling and roll right onto the ship, or it can roll up alongside and the carrier can lift it on. It just means shippers have more options.”
Some modules require kid gloves. Pressure vessels typically have heavy walls and don’t bend, so they can be lifted using a pair of cranes. But lifting can become an issue with some modules, Strom said. Normally, the base frame of a module doesn’t require stiffening to control bending movements.
“But if you pick up a 200-meter-long building from the ends (i.e., with two cranes), it’s going to sag in the middle,” he said. “That’s why the ro-ro concept is probably most suited to the very largest modules. When you have transport equipment beneath them, the equipment spreads the load over a much larger area, and that means less steel is required in the overall construction of the module.” Heavy modules become less attractive if shippers have to build in the ability to be lifted.
In the 1970s, Strom worked for the carrier Blaesbjerg. To move heavy cargo, “they mounted an arm on the side of a regular ship, and when the ship heeled toward the dock during a lift, the arm would rest on the dock to keep (the ship) stable,” he said. Heavy-lift was far more precarious then.
“The heavy-lift fleet has made leaps and bounds in technology and sophistication,” Strom said. “Three or four decades isn’t that much time for such a sweeping change. We have a lot more options out there, so it’s definitely a positive.”
Because heavy-lift has evolved, shippers have far more design latitude, but planning still must fall within the capacities of what’s available. “You can’t design it, build, and then afterward go, ‘Whoops, now I’ve got to ship it,’ ” he said.
Contact Janet Nodar at firstname.lastname@example.org.