Repower-e, progetto dello studio H3O di Milano
Andrea Colli, H3O: designing green boats, a must for the planet
It is tangible that something was already being done in the world with regard to the Green Deal before the Covid 19 pandemic, experts point to it all the more so today as the real factor of change for the whole of humanity, across every sector. Green Deal signals a new phase focused on reducing climate risk to a minimum and safeguarding human health and biodiversity: the challenge is to reduce CO2 emissions, partly by developing cleaner energy sources and green technologies, partly through the growth of a culture of holding each individual responsible, so that they have greater respect for the environment, changing their habits and lifestyles.
This is happening in every area, especially in the automotive sector, where the fleet of existing vehicles numbers in the billions and the use of engines powered by fossil fuels is gradually being replaced by different solutions, so-called alternative sources: renewable energy. A challenge of epic proportions has therefore begun, which will lead us in a fairly brief time to replace billions of vehicles, and which quite rightly concerns every type of human activity, including those related to leisure, to our passions, especially when these involve close contact with the environment.
To talk about what is happening in the field of water transport and boating, we interviewed Andrea Colli, Senior Architect of the Milan firm H3O Design, who together with his team has designed one of the most interesting electric boats, Repower-e, a project that is most certainly ahead of its time and the trend.
PressMare - What were, first of all, the focal points around which the project was developed?
Andrea Colli - In 2016 we received a request from a forward-thinking client, who works in public transport on the lakes, to design a new boat for navigation on Lake Garda - including when anti-pollution restrictions apply.
Together with our many collaborators, including CIMA 1915 (a company specialised in the production of electric motors), we designed a state-of-the-art zero emissions boat, 100% electric, suitable for both transporting people and leisure boating.
At the same time, it was necessary to be able to register the boat in accordance with the new, rather restrictive European directives, which in fact tended to significantly limit the number of passengers on board.
PM - How did you resolve this?
AC - We succeeded in our objective by reorganising the deck spaces thanks to the versatility of the electric motors, both in terms of positioning and thanks to their greatly reduced size, basically obtaining an open deck available for seating and for the boarding and getting off of landing areas required by the regulations.
The result, after a period of testing of this first project with a modular logic - again made possible by the extreme adaptability of the spaces and the absence of the engine compartment, was Repower-e, the 100% electric boat launched at the 58th Genoa International Boat Show.
It is a boat with modern lines, the deck is protected by an elegant central deckhouse with a roof that can be opened to various heights and a blend of classic materials such as teak. Boarding has been designed to be extremely simple and, with appropriate modifications, can also be made accessible to passengers with reduced mobility.
PM - Could it also be used as a taxi in the Venetian Lagoon?
AC - It's more versatile than the classic Venetian taxis, while at the same time echoing their elegance. Measuring 10.50 metres in length, including the stern platform, and 3 metres wide, it can board up to 12 people in addition to the driver.
PM - What characteristics are required for the hull of a boat that is created to be used with electric propulsion alone, and therefore with low power consumption?
AC: The hull has been designed to optimise the water lines at average operating speeds. These are speeds below or close to the hull speed. In addition, at the specific request of the customer, the hull had to be able to reach 16 knots with the power installed, so it had to be able to get to planing mode without major changes in trim, while maintaining sufficient stability both when on a straight course and when turning. The design compromise necessary to get a good response in both conditions was very complex to obtain, which is why the water lines of these boats are so particular.
PM - Is the vertical bow a fashionable whim or is there a technical reason for it?
Thanks to the vertical bow, the waterline length at hull speed corresponds to the overall length: this helps to distribute the submerged volume as much as possible along the length and to get as linear as possible a rocker from halfway down the boat to the stern. The maximum width of 3 metres is also due to a compromise between reducing resistance in navigation, the need for a usable floor area on the deck, and form stability in the first angles of heel.
The structure of the hull is also based on the type of propulsion chosen, which in this case is allocated to two propellers placed on the sides of the V hull, both for reasons of efficiency and to limit the draft. In addition, we focused a lot on being lightweight, using construction systems that are usually used on luxury yachts: the complete boat in this set-up weighs just over 3,000 kg and can carry a load of 2,900 kg.
PM - Since this is a passenger boat, a taxi boat, one would imagine that the naval design had to place great emphasis on the stability factor: how did you handle that?
AC - Ensuring the necessary stability was one of the most important tasks and was one of the most interesting parameters in defining the overall architecture of both the hull and the entire boat. We lowered the centre of gravity as much as possible, positioning the batteries as low as possible, in special longitudinal central compartments, which take advantage of the maximum depth of the boat (right at the V of the hull). In addition, the fundamental component of stability of form, the one that is most important at low angles of heel, is ensured by the presence of wide longitudinal rails, whose lines follow both the form of the hull wave and the disposition of volumes, allowing you to keep a constant trim with varying loads (in the public transport version with a maximum capacity of 29 passengers, boarding and turning operations were designed with 2,500 kg of passenger weight in mind).
PM - To ensure range with current technologies, electric boats must use an appropriate number of batteries: how did you solve the problem of weight? What specific measures did you employ?
AC - Increasing the capacity of the battery packs on board means increasing the total weight of the boat and thus increasing the resistance in navigation. Here again it was therefore a question of reaching an ideal compromise between total weight and battery capacity based on the real range requirement that you want to achieve. Having twice the capacity that you really need is useless: you would have more weight, more resistance and greater energy consumption. The ratio between the weight of the batteries in relation to their capacity has been greatly improved since the launch of the first boat in the open version. The one presented at the Genoa Boat Show has 20% greater capacity and a battery pack system that takes up much less space.
For this reason, the system must be able to adapt to updates and must therefore be modular in order to meet the varying needs of customers.
Of course, an indirect aid to the increase in efficiency is obtained from the control and limitation of weight, which is why the construction was done using only biaxial and unidirectional reinforcements, and epoxy resin with membrane moulding technology. This process allows you to have a final laminate with the precise ratio of resin and fibres, it also allows you to obtain finished surfaces on both sides from the moulding phase, eliminating the need for expensive and heavy finishing works.
PM - For the Repower-e project did you also carry out specific studies in terms of safety?
AC - The boat has obtained full approval from the classification bureau, it is a product that can be sold on the market with standards of stability and deck organisation in accordance with the current European directives for public transport on inland waters.
In several respects, this was the first boat of its kind, so much so that the certifying bureau, at least initially, used some of the parameters found on the first boat as a reference for its subsequent certification tests on other boats.
The same applies from the point of view of the systems: electric propulsion on boats of this type only existed through retrofits. Getting into the project in depth we found a degree of superficiality in the way in which several companies in the sector tried to fulfil our requests. Above all, there seemed to be a lack of unity of purpose among the manufacturers of components that needed to be part of the same system.
It was precisely the idea of viewing the systems as a whole that made the difference in terms of product quality and safety. Six years have passed and giant strides have been made in the field, going precisely in the direction we envisioned.
PM - Repower-e is not only a taxi boat, there are different versions of the design that see it used as a prestigious tender or a vessel for pleasure sailing in its own right, including in areas where heat engines are prohibited. Do you think this design could be the foundation for a new way of conceiving motor boating?
AC - Yes, absolutely. Regardless of the version, this is a new way of conceiving mobility on the water: free of emissions and noise, integrating perfectly with the surrounding environment and preserving it for future generations. Together with my team it is something that we try to do every day, in all of our projects, whether it's mass production or custom tenders.
No less than 5 years ago, thinking about sustainable mobility in boating was pioneering. Few people would listen to you, few considered the initiative economically sustainable. As far back as 2016, the first version of this boat was awarded the accolade of being an Excellence of Lombardy in design for mobility, after which I was very proud to achieve an honourable mention in the ADI (Association for Industrial Design) Compasso d'Oro Awards 2018 in the sustainable mobility category.
PM - Does this mean that in the nautical field awareness is also changing rapidly?
AC - Fortunately yes, but we have to take the issue of green boats very seriously, because it is a question of our future, everyone's future. To give you an idea of the level of quality of the project and its potential use, in 2017 Repower, a company operating in the electrical sector and one of the leading players in Switzerland in the generation of energy from renewable sources, which operates on the entire Swiss and Italian market, co-financed the development of the project and then bought it outright in 2018.
For the future we have new projects planned, to be developed with our many partners.