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Maritime Propulsion

December 19, 2023

Croatian Ferry Refit for Operations on New Route

The Croatian ferry Krk operated by the national Jadrolinija shipping company was retrofitted to cater for a new route with stronger winds and currents. (Photo: Jadrolinija)

Sometimes, a change in a vessel's operational profile requires considerable modernization or retrofitting of its propulsion system in order for the vessel to remain fit for purpose. And in some cases, newly required thruster performance features can be achieved with the help of modifications that preserve most of the existing units.

Earlier this year, the Croatian ferry Krk operated by the national Jadrolinija shipping company, was retrofitted to cater for a new route with stronger winds and currents. The open propellers of the Krk’s thrusters were replaced with new optimized propellers and fitted with SCHOTTEL VarioDuct SDV45 nozzles. The thruster upgrade comprised a mixture of overhauls and modernizations in accordance with the time schedule of the vessel’s planned maintenance cycle.

The entire retrofit process took place during the annual lay days between seasons. The thrusters were dismounted and reinstalled in Croatia by SCHOTTEL partner Alfa Marine. The conversion work on the thrusters themselves was carried out at the SCHOTTEL service workshop in Spay, Germany. A cost saving of around 50% was achieved by overhauling the existing thrusters – including the transportation costs to Germany – as opposed to purchasing new ones.

with modernization work completed, the ferry is responding more accurately to steering maneuvers and the autopilot makes fewer corrections thanks to the much-increased course-keeping stability. Hydrodynamical analyses from SCHOTTEL predicted the now realized top speed of 13 knots and various other advantages gained from using the SDV45 nozzle. In addition to the vessel’s increased course-keeping stability, the new nozzles also ensure smoother operation of the thrusters.

As an added benefit, due to the improved thrust and performance values of the Krk, Jadrolinija is now able to tighten the ferry’s schedule.

The open propellers of the Krk thrusters were replaced with new optimized propellers and fitted with SCHOTTEL VarioDuct SDV45 nozzles. (Photo: Alfa Marine)