Gustav Pielstick – the designer and his engines

The story of the German ship engine designer who worked for MAN before developing a family of medium speed engines in France.

When discussing the Ruston AO engine in Britain’s last major engine designs, mention was made of how many of these were replaced with SEMT-Pielstick engines. At the time, in the 1980s, this family of engines had emerged as perhaps the most successful medium speed design. Behind the success of the engine was its designer, Gustav Pielstick. Born on 25 January 1890 in Sillenstede, Friesland, Germany, Pielstick would go on to design a whole range of powerful diesel engines, and help to develop the design bureau SEMT (Société d’Etudes des Machines Thermiques). 

Design guru

After schooling in Wilhelmshaven, Pielstick began an internship at the Wilhelmshaven Imperial Shipyard, later attending the higher ship and mechanical engineering school in Kiel. In October 1911, he joined MAN as a design engineer where he worked on the development of submarine engines. During World War I, he was promoted to chief engineer and, after the war, worked on the development of the first MAN four-stroke crosshead engines for commercial shipping.  

At the end of the 1920s, Germany’s Navy wanted a high-performance diesel engine with a power to weight ratio of 6kg/hp, a previously unattained figure. By 1931 MAN and Pielstick had developed engines that achieved this performance. The first was tested in the training ship Bremse and later versions were used as the propulsion engines for the ‘pocket battleships’ Admiral Scheer and Admiral Graf Spee. 

In 1934 Pielstick was appointed director of the diesel engine department of MAN. Under his leadership, diesel engines emerged for ships, locomotives and stationary work. Pielstick paid particular attention to the development of engines with ever higher power density, based on the turbocharged submarine engine.

SEMT

After World War II Pielstick, who was seen as having been too supportive of the Nazi regime, left his post at MAN and moved to France in November 1947. There, together with six of his MAN engineer colleagues, he joined SEMT as technical director. The new company, established by France's ministry for industrial production in 1946 to develop engines that could be licensed internationally, combined five national companies: Société des Chantiers et Ateliers de Penhoët (Saint-Nazaire), Société Générale de Construction Mécaniques (La Courneuve), Société des Chantiers et Ateliers Augustin Normand (Le Havre), Société des Ateliers et Chantiers de Bretagne (Nantes), and Société des Aciéries du Nord  (Denain).  

SEMT’s first engine test beds were constructed in 1951 at La Courneuve. Pielstick's contribution as director was so successful that the organisation’s designs were soon licensed in numerous countries, including Germany. In the late 1950s, Pielstick retired from professional life and spent his later years in Lugano, Switzerland. He died in Zurich on 11 March 1961. 

There was a certain irony when, in 2006, MAN B&W AG bought SEMT-Pielstick given that Gustav Pielstick, having fallen out with the immediate post-war management, was told at the time of his leaving that “there is no longer any place in the MAN for men of this way of thinking.”

The SEMT Pielstick engine range

The Pielstick engine range was launched in the early 1950s as a family of monobloc, multiple crankshaft engines with output speeds of approximately 500 rpm. The PC1 was soon succeeded by the PC2 which reverted to a single crankshaft design, and was followed, in 1971, by the PC3 which featured an increase in bore size from 400mm to 480mm. The PC4, from the late 1970s, saw bore size further increased to 570mm. 

Longer strokes versions of the PC2, the PC20, and of the PC4, the PC40, appeared in the mid 1980s. There was further progress with increased maximum firing pressures and reduced specific fuel consumption and the engines achieved dominance of the medium speed market.  

Engines were available in-line and vee form with up to 18 cylinders and high power outputs, for example, the PC4.2 B long-stroke model from 1985 raised the output to 1,325 kW per cylinder. In its 18-cylinder version, the latter model was one of the most powerful four-stroke engines on the market at the time. 

However, developments in smaller versions of the rival two-stroke diesel, and their simpler maintenance requirements with fewer cylinders for a given output, saw the medium speed concept for propulsion fall from favour for most types of ship. Nevertheless, its main advantage remains the low height making it particularly suitable for ferries and cruise ships.

High speed for naval uses

SEMT-Pielstick designs continue to prosper, in the high-speed sector, particularly for naval vessels. The company’s PA range followed the design features of the PC family and culminated in the PA6. Initially intended as a locomotive engine, from 1975 it was adopted for maritime use, especially in naval vessels. In 1981, the PA6 CL long-stroke engine with reduced fuel consumption was released, followed in 1988 by the PA6 STC, which used sequential turbo-charging. In 1995, SEMT launched the final versions, the PA6 B and PA6 B STC, with increases in power and performance. 

John Barnes is a journalist and author and former editor of Marine Engineers Review.