A complex engineering marvel, the SS United States remains the fastest ocean liner ever built. She smashed the Queen Mary’s coveted transatlantic speed record on her 1952 maiden voyage and achieved an astonishing average speed of 36 knots (41 mph; 67 km/h). It was the culmination of a dream long held by the ship’s designer, William Francis Gibbs. He was proud of the “Big Ship.”
Gibbs shared credit for the new liner at a gala aboard the United States on June 28, 1952. He said:
The fact is, that this ship is the product of many minds, much enthusiasm, of people who with head and hand have joined in a great project and thus presented to their fellow citizens an example of something which has been denied these fellow citizens for 100 years.
Among those “many minds” was Elaine Kaplan. Her contribution to the new ship’s design was tremendously important.
A top engineer in Gibbs & Cox, William Francis Gibbs charged Kaplan to design the United States state-of-the-art propulsion system. She and her team threw themselves into the project. They exceeded expectations: during speed trials, the United States achieved 38.32 knots (44 mph; 71 km/h).
Without Elaine Kaplan’s contributions, “America’s Flagship” probably wouldn’t have achieved these incredible speeds.
Elegance and Engineering Know-how
Armed with a bachelor’s degree in Mathematics from New York’s Hunter College, Elaine Scholley started working for Gibbs & Cox during World War II. William Francis and Frederic H. Gibbs founded the naval architecture firm in 1922 as “Gibbs Brothers.” Their first major project was refitting the SS Leviathan (the ex-Vaterland) for American transatlantic passenger service. By World War II, the firm was designing ships for the Allied war effort. It’s estimated that Gibbs & Cox designed 70% of American tonnage launched between 1941 and 1945. Scholley thrived in the firm’s high-pressure environment and became a top propulsion engineer who eventually earned William Francis Gibbs’ high esteem.
In 1945, Scholley married fellow Gibbs & Cox engineer Howard Kaplan. The new Mrs. Kaplan didn’t let the social conventions of 1940s and 1950s America define her, however, and broke barriers.
Kaplan’s daughter, Susan Caccavale said of her mother:
She had an understated elegance. You could tell she was bright but she was so humble and unassuming that you would never know how accomplished and brilliant she was, which was part of her charm.
Gibbs & Cox was unique in that it hired people based on their abilities and expertise, regardless of gender or background. Regardless, Kaplan was one of only two women on the SS United States’ 50-person design team (the other being Rebekah Dallas). But no one questioned her presence. Like Gibbs, Kaplan had the uncanny ability to break down complex engineering concepts and explain them in such a way that laymen could understand them.
Gibbs put Elaine Kaplan in charge of designing the United States’ propulsion systems, and its propellers in particular. They were absolutely critical if the ship was to achieve its intended speeds.
Bad Vibrations
Since the creation of transatlantic express liners, naval architects had to balance speed and passenger comfort. These ships needed to run on a set schedule and sail through rough seas, all while ensuring minimal discomfort to those onboard. Vibrations from engines and propellers were a chronic problem that plagued great ocean liners like Lusitania, Normandie, and Queen Mary.
The propellers on an ocean liner need to spin fast. Very fast. For example, the Queen Mary’s four 32-ton propellers each turned 172 times per minute (or three times per second) at full speed. Fast-spinning propellers create tiny bubbles in the water, which disturbs the blades’ grip on the water. This is called cavitation.
The Shipyard, an awesome blog that I highly recommend checking out, wrote a post explaining propeller cavitation:
Because a ship’s propeller rotates through the water at an angle of attack, a pressure side and a suction side are created on each of the propeller’s blades. The faster the blades cut through the water, the lower the pressure on the suction side of the blades becomes. At a certain speed, the pressure on the suction side is so low that the water flowing over that area evaporates, forming vapor bubbles or voids. This happens because at “normal” air pressure of 1013.25 hPa, water evaporates at 100 ° C. At a higher pressure, the evaporation temperature is higher, and respectively lower at a lower pressure. Thus, in this case water starts boiling and evaporates at a pressure of 23.37 hPa at a temperature of 20 ° C.
Going into more detail, when the local pressure decreases below the vapor pressure, water evaporates, a cavitation bubble forms, grows larger and gets transported with the flow to a region with a higher pressure. At this point the bubble stops growing and when the local pressure exceeds the vapor pressure, vapor condenses starting from the wall of the bubble. Eventually, the surface of the bubble starts to break down in its weakest spot and the bubble implodes. During this implosion, the water flows back into the space to fill the collapsed void whereby pressure surges arise that can have orders of magnitude of several hundred MPa. This process creates pressure waves with high pressure peaks. If the vapor bubbles are in the vicinity or directly on top of a solid wall surface, such as propeller blades, the implosion produces a liquid microjet, which exerts high stresses onto the surface. The sudden release of energy causes pressure loads on the surface, which create crater-shaped material erosion in the propeller blades.
In addition to the erosion, the layer of bubbles packed onto the surface of the propeller blades makes them “thicker”. This increases resistance, as the blades move through the water, which in return decreases the performance of the propeller. Last but not least, cavitation can also cause loud popping noises and vibrations, which further affect ships and those travelling on them.
In short, propeller cavitation wears down propeller blades and sends vibrations through the ship’s hull. On a liner, this could cause tables to shake and mean sleepless nights for passengers. That wouldn’t do for the United States.
Kaplan and her team had their work cut out for them.
“Mrs. Kaplan is quite the equal of any technical person that we have in this place.”
Elaine Kaplan initially designed four 18-foot propellers with four blades each for the SS United States. This was a very traditional arrangement for ocean liners at the time. Kaplan made regular trips from New York to the shipyard in Newport News, Virginia to test propellers in model tanks. The 18-foot size was deemed optimal, and special attention was given to the pitch of the blades. But testing later showed that it still created bad vibrations. Kaplan and her shipyard colleagues put their heads together to come up with a solution.
In the end, the United States‘ propellers were configured in an entirely new way. While the ship’s two outboard propellers would have the traditional four blades, her two inboard propellers would have five. Testing showed that the ship would be able to achieve 37 knots (42.5 mph; 68.5 km/h) at full speed with minimal cavitation.
William Francis Gibbs typically wasn’t one to lavish compliments or praise. Of Kaplan’s achievement, he simply said:
Let me say that for my money, Mrs. Kaplan is quite the equal of any technical person that we have in this place. Now for God’s sake don’t get conceited and for God’s sake come in on time.
That was high praise indeed coming from Gibbs.
The Big Ship
On June 23, 1951, Elaine Kaplan proudly watched the SS United States’ christening and launch in Newport News. As she’d boarded the train for Virginia, her husband Howard gave her an orchid corsage to wear at the event. However, wanting to be seen as an engineer and not as someone’s wife, she took it off and put it away shortly thereafter.
After the United States’ highly publicized and successful maiden voyage in July 1952 (which she was unable to make), Elaine Kaplan left Gibbs & Cox to have a family. William Francis Gibbs offered her anything to get to stay on, but she politely and respectfully refused. However, Kaplan was immensely proud of the work she’d done on the “Big Ship.” A model of the United States was featured prominently in the Kaplan home, and it was widely known that working at the firm was one of the happiest times of her life.
Elaine Kaplan eventually returned to Gibbs & Cox as a marine engineer in the 1980s after teaching high school for years. She passed away in 1996.
Susan Caccavale noted:
In those days, a woman’s identity was to stay home and have children. If you were to ask my mother her identity, she would say a nautical mechanical engineer, and then a mother.
Leave a Reply