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Skyscrapers of the seas

Ship design is a dynamic story of adaptation

Blueprint plans for Donald McKay’s clipper ship

Image: Botanical Sculpture #5 god, by Azuma Makoto, 2012. Photo: Shiinoki Shunsuke; courtesy amkk
 

As architects and urban designers, we are drawn to the edges of our commercial ports. We are called on to design the buildings and facilities that connect the land to the sea. But there is a sea side to port design as well. Consider the role of the naval architects and the shape of their products. Look at any panorama of a commercial port, and focus for a minute on the vessels.

Architects design buildings that are firmly planted in the ground. The structural design primarily resists gravity. Buildings are not supposed to move very much — in fact, limiting the amount of sway in wind and earthquake conditions is a key consideration in tall towers.

By contrast, naval architects design structures that are fully intended to move, even when they are the size of skyscrapers. Their ships must be able to survive and maneuver reliably in raging storms and violent seas.

Naval architects are trained to accomplish this. They have their own tradition of education, naval “starchitects,” and historic accomplishments, many of which originated here. MIT’s naval architecture program was among the first in the nation and remains as one of very few. From the foot of the steps of MIT’s domed Building 10 on Massachusetts Avenue, look up. There, on the cornice to the left, “School of Architecture” is chiseled into the limestone. Now look to the right. “Pratt School of Naval Architecture and Marine Engineering” is inscribed on the same level. That department even has its own street entrance, framed by anchors.

Like port architecture, ship design directly reflects the economies and cultures that it serves. The landside and vessel design must also effectively accommodate the available point of contact at commercial ports. This interplay creates a fascinating story of adaptation.

Take the port of Boston. It was an international harbor from the day of its founding, and visiting ships had to contend with the shallow water near the natural shore of the Shawmut Peninsula. Reaching shore was a challenge, so in 1715 all 1,586 feet of Long Wharf were completed, built to dock ships with deep drafts.

But in the same era, many merchant ships were designed by their shipwrights to settle onto the bottom at low tide and then dock at shorter piers when the tide came in. With hulls known as “barks,” they were heavily constructed bulk carriers with shallow drafts and nearly straight floor timbers to make grounding them on the bottom easier. They were very maneu­verable in the small inlets and harbors of our coast.

Bottoming out was handy, but this type of hull design limited the size, shape, and speed of seagoing ships. As early America’s industrial age grew, merchants and manufacturers turned to faster ships with larger capacity — and deeper hulls. In the early 1800s, finger piers reached out from the shore while dredges removed mud alongside of them. Architect Charles Bulfinch helped lead the landside changes with his stone-sided wharf and marble-decorated brick storehouse designs for speculative investors at India Wharf. Many others followed.

Naval architecture seized the trend and took it to its practical limits in the age of sail. Naval architect Donald McKay revolutionized merchant shipping with his clipper ships. They were visually stunning, but their value was in their nautical brilliance. The maximum speed of a displacement vessel is derived from its hull length and shape relative to the fluid properties of water. McKay’s ships incorporated sharp, hollowed bows in front of exceptionally long, straight hulls that offered less resistance to the water at high speeds. These stable hulls could take on more sail area on taller masts, adding power to the equation.

Launched from his East Boston shipyard, McKay’s ships set records: the largest clipper ship ever constructed, the fastest sailing ship ever built, and the fastest passage from New York to San Francisco — 89 days.

But trains could top that, and soon did. Steamboats and steam trains rapidly co-evolved, meeting at tracks’ ends. In Boston, more mudflats were filled, shaping South Boston’s Fan Pier into a long curve, ideal for railyards. The famous Cunard Line brought steam passenger ships to an East Boston pier built in place of McKay’s shipyard. Its massive Caronia packed tourists and immigrants efficiently — 1,550 passengers in 678 feet of ship.

Still, these were small compared to the supersized cruise ships that ports accommodate today. Boston adapted by converting the former US Army’s troop and supply ship World War II departure terminal, now Massport’s Black Falcon Cruise Ship Terminal. Its 1,600-foot-long building and even longer dock are more than adequate for these giants. But unlike the past when such floating hotels were iconic features of Boston’s harborscape, these great ships are now largely hidden from view, tucked behind the taller, longer former Army dockside warehouse that is now the architect-frequented Boston Design Center.

Ship design, trucking, and railways became aligned in the 20th century with the advent of containerization. As the United States became a prosperous consumer economy, producer nations had to ship vast amounts of goods to our ports. But contemporary regulations effectively block harbor filling to create more land. So, the ships and ports adapted to the harbor edge we had already created.

The hulls of these container ships have open rectangular cross sections to carry boxy containers from the bottom of the hold to high above the deck. The hull size and shape result in immense torsional stresses, as they span waves from any direction. The naval architects and engineers responded with sophisticated torsion boxes running the length of vessels as integral elements of their double hull designs, using welded lateral plates connecting them to resist the torsion moments. It is like solving the famous twisting problem of I. M. Pei’s 790-foot John Hancock tower for a ship that is longer than that tower is tall — and with much greater forces at work.

Navel architecture callout

The international Council on Tall Buildings and Urban Habitat classifies “supertalls” as buildings above 984 feet. They are rising up all over the world, presenting architects with new challenges. And soon, their 1,200-foot maritime equivalents may be coming to Boston, when post-Panamax megaships slide into Massport’s docks after necessary dredging is completed.

Because of their greater size, such ships can flex so much that metal fatigue could compromise their structures. The naval architects and engineers must overcome unprecedented torsion “springing” (resonating and twisting with passing waves at a destructive natural frequency).

Unfortunately, the panoramas of our historic central harbor are graced only by reminders of the great ships that once docked at its wharves, like the preserved USS Constitution or the occasional visits of the Tall Ships. But keep an eye out for the vessels at the port’s active edges, and thank a naval architect for fusing beauty, efficiency, and adaptability in the craft. ■