20 Now, any Frauscher boat with both electric and IC-engined variants will be named such that the electrified model number will end in ‘0’, and the ICEpowered model number will end and begin with the same digit. This tradition is now entirely stylistic as the 858 Fantom Air and 850 eFantom are both 867 cm long. A history of two halves The 858 model was conceived in 2012 as a larger, modernised upgrade to the 757 St. Tropez, with a hull specified for stern drive propulsion (as opposed to the shaft drive typical of Frauscher’s higher-powered electric boats or the pod drive on 48 V systems). “It was the first boat we produced with Kiska, a design studio, perhaps most famous for working on KTM’s motorcycles,” Helmberger says. “They design many different vehicle types, but they had never done a boat before, and that was a major reason [why] we chose to work with them – we wanted to bring a new, fresh feel into the industry.” He concedes that Kiska’s open and honest inexperience in boat engineering brought significant challenges, particularly when it came to instructing them on technical areas, such as packaging, laminations and the correct construction of moulds. Frauscher therefore also consulted one of its routinely contracted naval architects, Harry Miesbauer (who in the past had designed boats for the America’s Cup and worked for Luca Brenta at Luca Brenta Yachts). “We put him and Kiska together to come up with the hull design, structure, packaging and materials of the original 858,” Helmberger recounts. “That was still challenging as they spoke different languages and had different priorities in their development styles. Nevertheless, the product was so successful in the end that we contracted the two in partnership again for many further models – in fact, roughly half of our current range was designed by this team.” The 858’s internal space had not been optimised for integrating an electric powertrain, however, as electrified boat powertrain technology was not mature in the 2010s. Having decided upon the next-gen Macan’s componentry, the first step for the teams at Porsche and Frauscher was to adapt the internal hull compartments for installing the battery, inverter, motor, transmission and control box. Much of the work in that stage went into redesigning and then engineering the internal space for mounting the battery pack – the single-largest component in the powertrain – and also in positioning the e-motor as being best for both thermal management and coupling it with the stern drive. A stern drive is also known as an inboard/outboard drive (or I/O). It is a form of marine propulsion that combines inboard power with an outboard drive. As such, the engine sits just forward of the transom (the flat surface at the rear), while the drive unit (also known as an outdrive or drive leg) lies outside the hull. Internally, Frauscher and Porsche have also used the term Z-drive, although this is more commonly applied in German than in English. In some cases, the team was able to use the exact same kinds of mounting parts used in the original 858’s IC engine-related modules. This was an advantage towards the team’s ambition of being as specific and straightforward as possible with regard to the installation and mounting instructions they were to pass to Frauscher, to ensure the shipyard team could quickly learn and repeat the integration process for the powertrain into the 858 hull to produce the ‘eFantom’ units. But the bulk of the challenge in the integration process was software, particularly in the engine control unit (ECU). For the project to be successful, Porsche’s team had to include as much of the original 858 boat and next-gen Macan powertrain as possible, with as few changes as possible; doing otherwise, they felt, would not be worth it, given the low production numbers that luxury powerboats are traditionally manufactured in. An estimate has been made to us that a complete rewrite of the battery management system (BMS) and other ECUs would have cost millions of extra euros. Hence, the principal objective during software integration was to take the original modules as they were and write intermediary modules to make the powertrain think it was driving a car. This meant using analogous data inputs and translating them as far as necessary for safe, smooth and efficient operation. A considerable number of simulations were performed, to repeatedly make sure the ECUs and boat-side Dossier | Frauscher x Porsche 850 Fantom Air Beneath the top deck, the e-motor sits at the back, the battery further forwards, and the inverter between them, with the controls box on top (Courtesy of Porsche) March/April 2024 | E-Mobility Engineering
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