A Venice taxiboat is on the way to being transformed from a dirty, exhaust-belching anachronism into a robust, high-tech hybrid.
But there were a number of challenges to overcome before getting it back into the water for the first tests. Not only did the planned launch see unseasonable, driving rain hit the Boat Stack in Southampton, but there was a hitch getting hold of the Duoprop propeller – though the local dealer, Marine Power, saved the day by driving miles to pick up an identical unit for loan. “Things like this only come up when you’re in the final assembly process,” explained REAP System’s Anton Evdokimov.
However, underneath these smaller niggles have been larger challenges, critical to the success or failure of the entire project.
Space, for example. The 20kWh, battery bank, (tailored for both a frequent charging cycle and a prolonged sub-6kn electric-only lagoon transit) is around 200kg. “Working out the best position for the battery - to achieve a perfect centre of gravity - and making it fit there was not easy” admitted Dennis Doerffel, CEO of REAP. On top of this, there needed to be “efficient yet safe” water cooling not just for the gears and inverter but the Xalt cells, in order to keep them at the optimum temperature.
The engine itself, a 3 litre, six-cylinder diesel Hyundai marine unit, had been chosen for its ability to get the vessel moving at 35kn during longer high speed runs while also keeping up the punishing 20 hour duty cycle common to Venice taxis. However, there’s no denying it’s not been easy to get the system layout right: “In fact we didn’t have this engine when we started adapting the boat,” he told MJ.
This is not, actually, a bad place to begin explained Dr Doerffel, since flexibility is at the heart of the concept. The idea that this hybrid set-up can be adapted across a number of very similar 8.8m vessels and allow the fitting of a number of different engines despite their slightly different alignment.
The engine is “totally fly-by-wire” he added: it has to be simple to operate. Therefore a CANbus solution is necessary because (although there’s an override feature) the inline hybrid system “has to make the decisions about when to cut in or out with the batteries or diesel engines”.
The next step in the process will be tailoring the control system to charge or expend the batteries automatically at certain trigger points said Dr Doerffel, hopefully arriving at a set of parameters that can easily be transferred to other builds.
When complete the boat will be taken back to Venice to demonstrate the system’s ability to deliver better, more efficient watertaxis and a cleaner city.
By Stevie Knight
