Brødrene Aa has over 40 years of experience building high-speed, lightweight vessels at its yard in Hyen, Norway. Over the past 12 years, the company has supplied Scandinavian customers with 25 catamaran ferries in progressively larger sizes. Though the first was only 18.5 m long, 27 m vessels have been exported to Sweden and 37.5 m vessels are now being used in Norway.
The yard’s new KRILO CARBO ferry, recently delivered to Croatia, sets a new length record at 41 m. Likewise, it is the first of Brødrena Aa’s boats to utilize Paradis Nautica’s Advanced Slender Catamaran displacement hulls. With 340 seats in two saloons, it provides a midship kiosk, a large area for stowed baggage and a crew area with mess, toilet/shower and twin-berth cabins.
For all of its firsts, however, the KRILO CARBO is the yard’s 32nd sandwich-composite vessel with skins of carbon fiber and a vinylester core. Like the others, it was vacuum infused using Divinycell H core from Diab, which Brødrena Aa has found to have the best capabilities for its applications.
Brødrene Aa was an early champion of carbon-fiber sandwich constructions, due to their reduced weight in comparison to fiberglass sandwich and aluminum. Carbon fiber provides four times the rigidity of fiberglass reinforcement, as well as two to three times the tensile strength. While more expensive than fiberglass, it creates a positive spiral where reduced structural weight leads to smaller power requirements and the ability to install lighter engines and smaller fuel tanks.
The resulting fuel savings easily outweigh the additional investment, which is exactly what appealed to Croatian operator UTO Kapetane Luka. With the high fuel taxes in Croatia and diesel at a cost of EUR 1.60 per liter, fuel efficiency is critical on the operator’s route of Korcula-Hvar-Split. The KRILO CARBO is the fourth sandwich-composite catamaran acquired by the operator since 2001 – and easily the most efficient.
The KRILO CARBO has two MTU 16 V 2000 M72 diesel engines, complemented by a Humphree interceptor on each hull for optimum trim. This engine setup yields a service speed of 31 knots. Yet despite the limited engine size, the vessel achieved a maximum speed of 36 knots on its first day of testing. With MTU 2000 engines instead of the MTU 4000 engines a more traditional construction would require, UTO Kapetane Luka can run its service with 1000 kW less installed power and 50% lower fuel costs.