The drive to conquer

The appearance of the Aquamatic, with its sterndrive linked to an 80hp petrol engine, arrives just at the right moment to be part of the major transformations that await the recreational boatyards from the early 1960s. The idea is not really new. In the 1920s and 1930s, some tried to replace the traditional transmission line shaft on board powerful racing boats with inboard engines. The French engineer Paul Bonnemaison and the Italian Guido Cattaneo draw inspiration from the fixed drives of the competition outboard engines seen at the time. A few “tourism” versions are created from 1946, but without the ability to raise the propeller, which is only available with outboards until 1957.

In the same year, Jim Wynne, a test pilot on the lake at Mercury’s secret outboard base in Florida, resigns to embark on a personal project: developing a new sterndrive transmission. The charismatic and formidable head of Mercury, Karl Kiekkaffer, is at the time unaware of all the technical assistance that he secretly receives from his own chief engineer, the highly inventive Charles Strang. Strang has already spent more than 10 years with plans drawn up for the future “Z-drive, but without having a positive response from his employer. He is the real instigator behind the operation. The outboard market is expanding rapidly, but with limited power levels and relatively high costs in the high-end sector. 

At the end of the 1950s, everything seems to be coming together to support the widespread adoption of recreational boating. The objective of Strang and Wynne is to bring together the benefits of mass-produced automotive blocks (price, reliability, variety, power) with the strengths of outboard transmission. At the time, Volvo supplies them with the machines and is involved, from the outset, in developing a system to considerably expand the powerboating ranges offered. In 1960, the Volvo Aquamatic is still the only one of its kind on the market, but from 1961, the competition gets organized, including other inboard engine manufacturers as well as outboard manufacturers, with Mercury leading the way and announcing the release of its “sterndrive”, which can be adapted for many different engines. Charles Strang, who was forced out by Wynne, has successfully sought to work a

For small and mid-size engines, including diesel, the Aquamatic triumphs from the mid-1960s, with more than 30 yards using it in both Europe and America. In the country of relentless competition, a trade war breaks out, with Chrysler, then O.M.C. with Evinrude, Johnson and others entering the fray. 

At the end of the 1960s, Europe has more than 10 sterndrive propulsion brands, with possible adaptations for a range of engines, taken from the automotive industry in most cases. Even Porsche and BMW get involved, while France has R.H.F., François, Peugeot and Constantin. Many of them will quickly disappear as a result of the economic contingencies, the international situation and the market’s demands. 

From the late 1960s, despite the constant progress with outboard engines, the Z-drive continues to develop its market shares, with the four-stroke petrol engine consuming less than the two-stroke outboards, without forgetting the growing presence of diesel units, on which Volvo still has a lead.