off ” due to their very high speed combined with the lightness of the hulls themselves. That’s how and why the ground effect idea and the lift factor came to be exploited solely in competition models for many years, at least up until such a time when someone down sized this technology so that it could be deployed more safely for more conventional usages. So the inevitable advent of A2V company. A2V is short for Advanced Aerodynamic Vessels. This recent research company founded in 2013 has been focusing on fluid dynamics ever since inception and has drawn up extremely fast boats which are truly efficient in terms of energy. A2v’s founding members have since developed and patented some of their project work in line with passive ground effect findings so as to build a new kind of boats with the same name A2V. This is not a mere slogan because the company’s team of young engineers have already built two boats of the kind with a third currently being built and we’re not talking about small water craft! The first one off the chocks is an A2V- 25- CB. It was delivered in January 2018. This model carries up to 25 passengers with a top speed of 40 knots. It has been designed to carry crew to and from offshore platforms in west African waters. Peschaud International is the owner of this French build named “Clementine” with an LOA of 15 metres and a beam of 12 she’s powered up by a pair of hydro- jets thanks to two 600 HP engines but uses half as much fuel by comparison to others in aluminium owned by the company which translates into a yearly saving of 500,000 litres of diesel fuel per unit. Half a million litres saved per unit per year is by any standard a considerable saving. The second unit an A2V- SHUTTLE which was delivered September last carries 10 passengers at up to 50 knots ferrying clients staying at luxury hotels on lake Leman in Switzerland. With an LOA of 12 metres and a beam of a little over 7 this craft shuttles a greater number of passengers in less time and with less fuel when compared to other models currently used. And above all the degree of comfort the A2V offers is comparable to business class! These results have been achieved thanks to passive aerodynamic lift and thanks to A2V engineers’ fine tuning, the details of which are shown in the appropriate box. The technology deployed has entailed a clearly visible conditioning of the vessels’ shape which resemble large closed sea shells which means that interior spaces are inevitably penalised while the exteriors are practically nonexistent. The sum of these factors do not encourage any recreational use at least for the time being as it is the very “wing like” shape they possess which delivers the performance obtained. However the possibility of opening up portions of the existing external “body” is being examined so as to enjoy several external areas along the rear winglet which according to A2V’S engineering team can convert into a terrace overlooking the sea. There’s
La tecnologia messa a punto con gli A2V che rende possibile, A2V’S fine tuning of all the technology involved translates into safe passive aerodynamic lift and efficiency which is based upon a proportional balancing of two factors: the craft’s hydrodynamic and aerodynamic components. The aerodynamic part is represented by the above water structural section resembling wings which develop lift or vertical force which makes aircraft fly. The hydrodynamic part is made up of two identical catamaran hulls connected to the wing superstructure. As for A2VS in addition to the lift generated on the back ( top of the wing) another vertical force comes into play due to the quantity of air channelled between the two hulls which is compressed between the lower section of the wing or face with the sea surface. The sum of these vertical forces will partially lift the hulls off the water surface thereby notably reducing drag. In fact having the hulls advance not in water but through air ( which is 1000 times less dense than water) means that the required thrust forward is considerably very much less. As you probably know lift effect will grow exponentially as speed rises. Air compression effect will increase between the sea surface and the wings giving rise to what we know as WIG or wing in ground effect. As opposed to conventional ships where all of this represents added drag, instead where A2VS are concerned this means exploiting ground effect to partially lift the hulls off the water thereby decreasing submerged volume up to 50% which translates into much less drag. In conventional hulls drag effect increases exponentially as speed increases the opposite of which happens in A2VS. Above 25 knots all of this brings about a series of significant advantages. To begin with, less power is required by the engines which therefore saves fuel. For example, when a conventional fast boat usually requires 30 litres of diesel per passenger per 100 km at 40 knots, an A2V requires only nine litres and what’s more not at 40 but at a ground speed of 50 knots in the same sea conditions. Furthermore, this remains true irrespective of the ship’s size, no matter whether it is 12 or 30 metres long and whether it is carrying 10 or 100 passengers. Up until today high speed over water has been the prerogative of large ships carrying considerable numbers of passengers over long hauls which allow shipping companies to better amortize very high fuel consumption costs required to cruise at 40 knots with conventional fast hulls. We’re talking about catamarans or semi- planing single hulls which despite their capacity to reach 50 knots and more, rarely go beyond 40. In fact this is due to the fact that only a handful of extra knots are enough to double consumption. To sum up in plain words, the technology which A2V has developed and patented is best expressed with the following slogan on the company’s website ( www. aavessels. com): “safely transferring, the entire weight of the ship from water to air”. In addition to the advantages in terms of speed and of reduced consumption, the technologies deployed on A2VS translate in further benefits when compared to conventional fast hulls beginning with safety. The attentive and in depth detailed study of the above surface aerodynamics, of the hydrodynamics of the hulls, of the fine tuned distribution of weights have gone into harmonizing and balancing all the forces which come into play when cruising at several diverse speeds in such a way as not to have to resort to active stabiliser systems necessary in conventional hulls to control pitch and roll with flaps for instance, interceptors and so on. In an A2V all of that is not necessary since sea keeping qualities are enhanced naturally by an air cushion which is entrapped between the two hulls guaranteeing an all round smoother ride.
The A2V-SHUTTLE is well equipped with surface props. the special stepped geometry of the hulls recalling those of hydroplanes can be clearly seen.