How are ships built?
How are ships built? Building a small boat is relatively straightforward: form the hull, attach the engine and other electronic components, and it can go on a trailer to be transported anywhere. The entire process could last just a matter of months. But what about something bigger, say a cargo ship over 200 meters long? Large vessels are built in pieces and assembled later. These ships take years to build and can cost hundreds of millions of dollars. Today we’re going to take a look at how huge ships are built and what it takes to get them seaworthy.
How are ships constructed?
Construction starts with bending plates to match the curve of the ship’s hull. Since the 1940s, ships have been mostly made of welded steel, and since the 1950s, specialized steels have been used to eliminate brittle fracture. After 3D modeling, hydraulic presses are used to bend the plates into the correct shape. Plates are pressed cold, and can spring back a bit after forming, so this has to be taken into consideration. Rollers are also used to create some of the contours, plates are rolled through three rollers, with the pressure applied from the roller above forming the plate. In the last method, heat can be used to bend the plates. Frames are used to strengthen the hull, and are bent in a similar way with pressure or heat, to conform to the hull’s shape and reinforce it. If you really want to get into the weeds on ship hulls and how they work, check out the characteristics of hulls and course stability in Marine Insight’s article.
Image Credit: Marine Insight
Once the hull pieces are shaped, framed, and ready, they are assembled. This is a fascinating process where massive pieces of metal are brought together to form a complete ship. The construction is done in segments called sub-assemblies. These assemblies are welded together to form larger and larger pieces, eventually making up prefabricated sections. According to Wikipedia, “Entire multi-deck segments of the hull or superstructure will be built elsewhere in the yard, transported to the building dock or slipway, then lifted into place. This is known as "block construction". The most modern shipyards pre-install equipment, pipes, electrical cables, and any other components within the blocks, to minimize the effort needed to assemble or install components deep within the hull once it is welded together.”
In the video below, you can see massive sub-assemblies being brought together:
Video Credit: The Sea Lad
Where are ships built?
According to the New York Times, “Today, more than 90 percent of global shipbuilding takes place in just three countries: China, South Korea and Japan.” However, the federal government is a significant customer of the American shipbuilding industry. Between military vessels and the Jones Act, which ensures that domestic moving of goods between United States ports is done by ships owned and operated by Americans, over 400,000 jobs are supported through American shipyards.
Image Credit: New York Times
In San Diego there is a shipyard run by General Dynamics NASSCO. They’re building two identical ships for Matson that will travel back and forth from the continental United States to Hawaii. The ship in the photos is called the Matsonia and is a modest-sized ship of over 600 feet long. According to the New York Times, it will “be capable of carrying thousands of 20-foot-long containers and 500 cars and trucks — as much as 57,400 tons of cargo in total.” This is part of almost 13 million tons of cargo that are shipped to Hawaii each year.
Image Credit: New York Times
Depending on the type of ship, there are big ceremonies that go along with a new vessel, including naming, keel-laying, handover, and christening. With a vessel like the Matsonia, this would likely include keel-laying and christening.
Image Credit: Society of Sponsors of USN
Happy Fun Fact Friday!