There was no sail. No one was rowing it along. Yet the sharp-nosed launch was moving, cruising quietly along the Neckar River near Cannstatt in August of 1886. Maybe an electric motor was hidden under the hutch in front of the helmsman? Porcelain insulators and copper wires along the sides suggested that it was. Gottlieb Daimler was certainly up to something, he and Maybach in that little lean-to they called a workshop. But it couldn’t be one of the noisy, smelly, smoky and dangerous gasoline engines the pair had made last year – or could it?
The secret boats
Powering the launch was the identical 226 cc single-cylinder engine that Daimler and Maybach used in their 1885 carriage and two-wheeled “riding wagon.” The first portable four-stroke, it gave 1.1 horsepower at 650 rpm. Strollers along the bank of the Neckar saw its test runs with Daimler’s co-workers on board. The real show came at 3 o'clock in the afternoon of October 13th when dignitaries from Baden-Baden were invited to a jaunt on the little Waldsee Lake south of that resort town.
“We hear that the inventor has had three boats built according to his system so far,” reported the Schwäbischen Chronik, “the larger of which can accommodate ten people and the smallest two people. Daimler himself demonstrated the middle one, named Rems, operating the engine and controlling the steering. The former is located in the middle of the boat and takes up little space, as the mechanism is functionally mounted in the rear, simply constructed. The engine works regularly and without any noticeable noise, whereby the consumption of petroleum is minimal. The boat darted around the Waldsee with swift agility and beauty. Mr. Daimler received the fullest appreciation for his beautiful invention.”
Daimler’s son Paul related, “This first boat was fitted with electrical insulators and wires during the day in order to keep the fact that it was powered with petrol a secret. My father’s explanation was: ‘It runs on oiltricity.’ The engine was removed and reinstalled on a daily basis.”
His suggestion of electricity was Gottlieb Daimler’s strategy to deal with a wary public, who were aware of gasoline's high flammability and propensity to explode. He countered this by calling its fuel “petrol,” the English term for gasoline, which Daimler knew from his stay in Britain. “Petrol engine” sounded less problematic because people were used to petroleum as fuel for lamps.
Explosive gas marine engine
On October 26, 1886 in France, Daimler first registered a patent for his “Device for operating a screw-shaft of a boat by means of a gas or petroleum engine.” Its American patent was filed on November 9, 1886, rather spoiling the effort to divert attention from its fuel by its title: “Explosive-Gas Marine Engine.” In fact, his patent included cylindrical containers for gas fuels at atmospheric pressure and more. His other patents discussed storage for “petrol.” Its drawings detailed the way water was scooped up to circulate through the engine’s cooling jacket and then released at the rear. A crank at the front of the engine dealt with starting.
While the engine’s massive flywheel was internal, it drove a simple external clutch. Effecting its engagement was the propeller shaft, which was free to move fore and aft in its bearings. To get the boat under way, the shaft with its integral clutch-driven element was moved forward into contact with the engine-driven element, which initiated drive. Thereafter the propeller’s forward thrust sufficed to keep the clutch engaged. "Without altering the speed of the engine," said Daimler, "the speed of the propeller, and consequently the motion of the vessel, can be increased or decreased at will or entirely stopped by simply causing the frictional coupling to be brought into contact with greater or lesser force."
For reversing the drive – one of the features that flaunted the boat’s maneuverability – Daimler and Maybach fixed a disc to the propeller shaft in a position where it could be contacted by two discs at the sides that could also press against the clutch’s driving element. Two coordinated bell cranks pushed the disc pair into contact with those fore and aft to provide reverse gear. Controls for this function and others of the drive were linked to the internal passage of a vertical shaft. The latter carried handlebars the pilot operated to steer the craft through a chain to the rudder that was twisted so the boat turned where the levers were aimed.
These features figured in the three boats commissioned by Daimler-Motoren-Gesellschaft (DMG) in 1886. With room for ten, the Neckar was the largest. The Rems was in the middle and the two-passenger Schwaben the smallest. After the patent was issued the inventors stepped up promotion of their new creation. An appearance by Wilhelm Maybach with a Daimler motorboat in Frankfurt am Main in the spring of 1887 was a crowd-pleaser. There the “King of Designers” drew attention at a rowing regatta with his boat by cruising rapidly up and down the Main River. Even the police took an interest in what the novel craft was up to.
Boat manufacturing
Series production of motorboats by DMG began in 1888. The young company even built its own shipyard at the bend of the river in Bad Cannstatt for this purpose. There the hulls provided by boat builders were fitted out with the company’s machinery. On October 15, 1888 Hamburg on the Elbe was the site of an impressive demonstration: The 23-foot Die sieben Schwaben, powered by a 2-horsepower engine at 740 rpm, swam silently in the wake of the tugs that accompanied Kaiser Wilhelm II on his journey through the new port of Hamburg.
A notable creation that year was the motorboat Marie, built for the family of German Reich Chancellor Otto von Bismarck and named for his daughter. With a hull like that of the Neckar made by Anderssen at Neckarsulm, the craft was richly decorated by Stuttgart experts Paul Stotz & Co. Today it is on permanent display at the Mercedes-Benz Museum.
Motorboats quickly became a sales hit for Daimler. After further demonstrations on Lake Constance and in Sicily, customers were convinced. Daimler-powered boats were delivered to remote lands, as for the Sultan of Morocco. His magnificently equipped craft, delivered in 1892, was disassembled into six pieces and transported on camels to this early Daimler VIP customer.
Wilhelm Maybach’s first four-cylinder engine was shipped to New York on August 21, 1890. Intended for marine use, it displaced 6 liters and produced 12.3 horsepower at 390 rpm. Another seagoing engine was available days later, a 2.4-liter giving 5.9 horsepower at 620 rpm. Daimler was on a roll. In fact, motorboats and their power units were the principal product of the early DMG, playing a crucial role in the signing of export contracts to Britain, the United States and other nations.
Not to be outdone, Mannheim's Benz & Cie. also produced marine engines. The first Benz-powered motorboat could be spotted on the river Spree in 1887, followed by the lodging of a Benz patent on August 9, 1888, for a reversing device using bevel gears – a concept mooted in Daimler’s patent. Limited production of motorboats began in Benz's Mannheim factory.
A legacy of marine engines
Gottlieb Daimler was often quoted to the effect that the motorboat in particular contributed a great deal to eliminating the considerable prejudice that was then held against “explosive” gasoline as a fuel. The lively interest shown in motorized boats thereafter meant that marine engines had the largest share of Daimler production for many years. When the DMG celebrated its first decade in 1896 with a poster featuring all its products, marine applications were front and center.
Into the twentieth century, the first powerful racing machines were boats, not cars. Although they didn’t figure among the winners, craft with Mercedes engines were among those entered for the big April 1904 races at Monaco. Soon the German Navy took a keen interest in this newfangled method of marine propulsion.
In 1909, DMG delivered a 100 horsepower diesel to the Navy for use in a ship tender. This led to a series of marine diesels giving up to 150 horsepower. Alongside this, DMG built gasoline marine engines with upwards of 60 horsepower. September of 1911 saw Benz deliver its first Hesselman-patent two-stroke marine diesel engine. Benz was the sole German licensee of the Hesselman process, which was used by the engine that powered the ship used for polar exploration by Norway’s Roald Amundsen. From Hobart he cabled: “DIESEL MOTOR SPLENDID.”
Benz and Daimler built engines for the navies of both Germany and Austria-Hungary in World War 1. By this time, the works in the Berlin suburb of Marienfelde, acquired in 1902 to expand car production, was DMG's principal production plant for heavy engines. Its first engine designed for submarine use was the 109-liter MU 256, which gave 300 horsepower at 450 rpm and was ultimately developed into a 500-horsepower version.
The Benz counterpart was its six-cylinder S6Ln, making 450 horsepower at 400 rpm. Like its successors, it used the Hesselman propeller-reversing system which exchanged inlet- and exhaust-valve functions and tweaked other parameters. During the war, Benz supplied 72 heavy diesels for submarines; Daimler built 64 lighter-duty diesels for underwater craft.
Porsche on deck
With peace in 1918, orders for advanced marine engines were thin on the ground. At DMG, a new board member for engineering from 1923 was Ferdinand Porsche. He was encouraged by news that the Navy was visiting the works at Untertürkheim. Leading the Navy’s delegation on the morning of November 24, 1926 was Ministerialrat Wilhelm Laudahn. Scant weeks younger than Porsche, Laudahn was an engineer who had introduced diesel power and directed other advanced technical projects for Germany’s Navy. Accompanied by two colleagues, Laudahn met with Wilhelm Kissel and Richard Lang as well as Porsche.
As soon as possible, said the visitors, they would like to see a supercharged aero engine making 800 horsepower in air- and water-cooled versions. This led to a lively and detailed discussion between the two technicians about the implications of this request. Kissel asked whether this was likely to develop into a regular business for Daimler-Benz and also whether the Navy was prepared to provide financial support for the engines’ creation. This was great news for the company, although it was for use in the air rather than on water.
For Ferdinand Porsche, here was a happy reminder of the way the Austro-Hungarian Navy had commissioned a V-12 engine from Austro Daimler. As in that undertaking, the aim was to have a suitable power unit for the Navy’s future large flying boats. How big did an 800-horsepower engine have to be? Any risk of failure was skirted by settling on a capacity of 53.9 liters for the base engine with supercharging as a bonus. Each of its cylinders displaced 4.5 liters, as much as a luxury car of the era. This would be the largest engine that Porsche had yet built.
The F2, as it was dubbed, was a 60-degree V-12 with each bank having a single overhead camshaft. An array of shafts and bevels at the engine’s anti-drive end turned the camshafts, twin water pumps along the flanks, ignition apparatus, dry-sump lubrication pumps and, indirectly, two Junkers fuel pumps. Four vertical valves per cylinder were opened by individual roller fingers for exhausts and a single forked finger for the inlets. A supercharger at its tail could be engaged from the cockpit.
Developed through 1929 and into 1930, the F2 made 800 horsepower at 1,580 rpm at sea level and 880 horsepower at 1,600 rpm takeoff power. Maximum supercharged output was 1,030 horsepower at 1,700 rpm. It weighed 2,160 pounds with all accessories including the reduction gear. Its output figures ranked the F2 among the most powerful aero engines of its era, such as the Fiat A25 of 950 horsepower and Sunbeam’s massive Sikh III airship V-12, with 1,000 horsepower.
Only two prototypes of the F2 marine engine were ever produced. While neither ultimately reached installation in a naval vessel, the engines were the subject of testing through 1932. Porsche’s departure at the end of 1928 seemed to deflate the company’s interest in this aeronautical project with its obvious military implications. It did however, lead to a marine adaptation version that the Navy also commissioned.
Naval applications
The marine version of the 53.9-liter V-12 was the BF2. In all respects its features echoed those of the F2, with its reduction gear inverted so that it suited a low-placed drive to a propeller. Its cooling system still preferring fresh water, preferably distilled; it required a heat exchanger to interface with seawater. Fuel was to be either leaded gasoline or a half-and-half blend of gasoline and benzol to produce a supercharged output of a steady 800 horsepower at 1,600 rpm or 950 horsepower at 1,700, sustainable for half an hour at a stretch.
In the post-Porsche era three of the BF2 versions of his design powered Germany’s first modern Schnellboot, a fast attack craft. Commissioned from Bremen’s Lürssen in August of 1930, this displaced 51.6 tons and was mahogany-planked on an aluminum frame. Ultimately known as S-1, first of the Schnellboot line, it was powered by three BF2 V-12s. While the center and port engines had conventional rotation, the starboard BF2 had reverse rotation to minimize torque effects.
Three of these boats were launched, fitted with two torpedo tubes, a 20 mm anti-aircraft weapon and machine gun. All had BF2 power with 34 knots of sustained speed. This was an important foot in the door for Daimler-Benz, which competed with Mannheim for the supply of engines for subsequent S-boats. With petrol engines rejected on the grounds of their flammability, diesels were preferred. Daimler-Benz eventually prevailed with its marine diesels.
Airship applications
Daimler-Benz's seagoing diesels traced their origins to yet another version of Ferdinand Porsche’s F2 V-12. First run on November 14, 1930, this was the OF2, the ‘O’ indicating Ölmotor or oil engine. It had new valve gear with twin overhead camshafts on each bank, still shaft-driven. At the center of its vee were two six-cylinder Bosch injection pumps in line, pushing fuel oil to the prechamber at the center of four valves atop each cylinder.
With a compression ratio of 16.0:1, no supercharger was fitted to the OF2, which carried reduction gears in its initial version. Called from Benz to Stuttgart after Porsche’s departure, new engineering chief Hans Nibel’s right-hand man Fritz Nallinger took charge of testing, including high-speed diesels. Test results with this prototype led directly to the design of the 1933 Daimler-Benz LOF 6, soon renamed the DB 602, an 88.5-liter diesel designed for airship propulsion.
Developing a maximum 1,320 horsepower and weighting 4,360 pounds, the DB 602 powered two Zeppelins, the LZ 129 Hindenburg and its sister, LZ 130 Graf Zeppelin. This was a high-profile coup for Daimler-Benz, for Zeppelin airships had long been solely Maybach-powered. Fittingly for such a starring role, the V-16s were handsomely designed and finished.
V-20 engine & World War II
Under its MB 502 designation for the Kriegsmarine, the same diesel V-16 powered four of the 1933 series S-boats, each of which had three engines. The MB 502 also served as the starting point for the magnificent V-20 MB 501 diesel, whose 1,500 horsepower at 1,480 rpm output gave it a range of military applications, including later and faster S-boats with three such engines. Remarkably, two Type IX D1 fast cruisers were powered by six such engines apiece, a total of 120 cylinders per craft.
Daimler-Benz's marine engine and Schnellboot contracts continued after the outbreak of World War II. In 1939, arch-rival Auto Union was nibbling for a share of the Kriegsmarine’s business. The Daimler-Benz board voted to ward this off by laying down a second production line at Marienfelde, “allowing the retention of Daimler-Benz’s monopoly in an area that it saw as remaining highly profitable even after the war,” wrote historian Neil Gregor.
Daimler-Benz AG was less successful in getting permission to build marine engines at its Genshagen plant near Berlin. To compensate, additional acreage at Untertürkheim was devoted to naval-engine production. However, the still-new second line at Marienfelde was soon uprooted to make room for tank production and moved to Untertürkheim to create a concentration of large-scale naval engine production. The workforce there was solely German, no prisoners of war being engaged for security reasons.
Postwar marine
Management's idea of expansion to plan for a post-war world worked well. In peacetime, Daimler-Benz enjoyed strong demand for its marine engines. More recently, since 2010 the company has been working with select partners to design watercraft to a high standard under the label “Mercedes-Benz Style.” In 2016, Silver Arrows Marine collaborated with the Stuttgart company to build an impressive 14-meter luxury cruiser, the Arrow 460-GT.
Perhaps the most striking postwar use of a Mercedes-Benz engine on water was the 300SL’s slant-six – the M198 – installed in racing speedboats. At the end of the 1950s, the fuel-injected six powered two record-breaking boats owned by early company shareholder Herbert Quandt.
A less-privileged personage also took advantage of the 300SL engine for boat racing – the Austrian Peter Haas, who emigrated to South Africa in the 1930s. His contacts in pre-war motor racing paid off when his friend Maurice E. “Bobby” Bothner, who had raced a Maserati and Bugatti, arranged for him to be released for the duration of the war. Among his activities, Haas took up speedboat racing.
He competed with a hydroplane named Blue Peter. For power, Haas turned to his brother, who had worked at Steyr Puch in Austria and was now in the United States designing tanks. The fraternal tie led to Daimler-Benz, which had built special 300SL engines for the 300SLS raced by Paul O’Shea to an SCCA class championship in 1957. These had aluminum blocks and fabricated inlet manifolds reducing their weight by 135 pounds. Top-end tweaks brought power to 235 horsepower.
His brother worked his Stuttgart contacts to wangle a 300SL engine for Blue Peter. Installed with a reduction gear, the thoroughbred six stood up to the high-revving demands of boat racing through several seasons in the late 1950s. After winning several championships, Haas had to give way to progress, selling his special 300SL six to fund the purchase of an American V-8. The rare engine’s whereabouts are unknown today.