Effect Ships International AS (ESI) is reporting extraordinary results from tank testing of their Air Supported Vessel (ASV) mono hulls, in the SSPA towing tank in Gothenburg, Sweden.
ESI's patented ASV Mono hull underway in the towing tank at 30 knots
A 50% reduction in hull resistance over market leading conventional hulls is not commonplace. But that is exactly what was recorded. Deduct 3-6% to power the lift fan system, and there is still a 40% + reduction in powering or fuel consumption left.
Yards and end users alike are frantically searching for ways to beat the high fuel costs and to improve environmental aspects. Different kinds of air based solutions are evaluated. Air lubrication and air bubbling techniques are investigated to improve performance and reduce hull resistance.
Ulf Tudem, general manager for ESI is convinced ASV technology is the most efficient. "It is unquestionable that a full separation between the vessel's hull and water, by means of a proper layer of air (ASV) will reduce resistance more than use of an air and water mix (air lubrication) on the same underwater area. "Bubbling the hull" will have the least hull resistance reducing effect of the three concepts."
BB GREEN, a project under EU 7th Framework will be using ASV technology. A 7 partner strong European consortium is developing the world's first Zero emission fast ASV commuter ferry, to be operated on battery power only; and with a design speed of 30 - 35 knots. The vessel will have a length of approx 20 m with a beam of 6 m; and will be designed to carry up to 100 Pax.
Although the BB GREEN ferries are intended for fast commuter services in and around cities and densely populated coastal regions, the similar types of ASV hulls may be used for other types, sizes and applications of vessels.
Fast ferries, water busses, cruise ship shuttle crafts, crew boats and workboats of different sizes and kinds.
The BB GREEN ASV Mono hull, now tank tested at SSPA, is designed for relatively sheltered waters. Low hull resistance over a wide range of speeds and modest wake wash have been key design objectives. State of the Art planing hulls has been used as the bench mark. Resistance tests were carried out at speeds from 10 knots all the way to 50 knots, full scale values.
To the amazement of the SSPA test team the ASV displayed a very low resistance already from 10 knots, corresponding to approx half that of the planing craft. Between 15 and 35 knots the hull resistance curve was almost flat, and above this speed the increase was modest.
Wake wash was also pleasantly low, and well below the levels set by the Dutch Authorities for operating i.e. around Rotterdam, which is a targeted operational area for the BB GREEN. Dutch ferry operator Aqualiner is the end user partner in the project.
ESI will soon start another ASV Mono project; design development of a 24 m fast ASV Environmental Ferry, for operation on routes along the Norwegian coast. A soft motion hull form will be developed tailor made for use of Volvo Penta IPS propulsion system. The project will be supported by Innovation Norway. Collaboration partners will be Br. Aa, Diab and ferry operator Torghatten Nord. SSPA (Sweden) and Studio Sculli (Italy) will also contribute.
In Indonesia the first ASV fast crew boat is under construction, a 40 knots fast 22 m constructed by Pt. Eka Multi Bahari.
Source: ESI
