Mention the name Porsche and usually cars come to mind, but in 1959 Porsche began promoting an air-cooled marine engine in the U.S. called the Type 729. Weighing in at 285 pounds, it was nicknamed the “light engine for lightweight boats.” Based on the 1.6-liter, four-cylinder boxer engine used in the Porsche 356 A, the original 729-type marine engine was offered as a transom drive, although Porsche also planned to offer it as a traditional inboard with shaft and prop. Ferry Porsche, son of Porsche founder Ferdinand Porsche Sr., installed one of the first 729-type engines on his personal motorboat, which he tested on Wörthersee Lake in Austria. Producing 52 horsepower at 3600 rpm, the engine offered features that the company claimed others did not. Porsche said that apart from its light weight, air-cooling had numerous advantages, including “no cooling-water corrosion or water filtration requirements, rapid warm-up of the engine resulting in less wear, virtually no sludge, and immediate full power.” Fresh air was fed to a cooling fan that kept the engine from overheating and the engine also provided cabin heating. The company claimed that “air-cooling abolishes all inconveniences of the past done away with.” That included corrosion by salt water. Nonetheless, Porsche gave the crankcase a corrosion-resistant coating. “There is no need to check the cooling water or use anti-freeze,” the company’s literature claimed. “The Porsche Air-Cooled Marine Engine is ideal for year-around enthusiasts. With a Porsche boat engine, you’re installing a true powerhouse on your boat and thus ensuring the success of your boldest water sports plans.” By 1959, the 729 engine was used on search and rescue boats, and by 1960 it also appeared on narrow-gauge locomotives. Regardless, the air-cooled marine engine would never meet the success of Porsche’s car engines. While mariners today often get their power from Mercurys, Yamahas and Volvo Pentas, Porsche has not abandoned its efforts at boat propulsion. Today the company is using the electric technology used in the Porsche Macan car to partner with Frauscher, an Austrian boatbuilder, to develop a new electric boat; The Frauscher x Porsche 850 Fantom Air.
This article was originally published in the January 2024 issue.
