ZAP - Zero Emission Auxiliary Propulsor

ZAP: Zero Emission Auxiliary Propulsor

The International Maritime Organisation (IMO) has introduced several measures to lower the CO2 emissions from the fleet in active service and the permissible limits will be further reduced in the coming years. This is due to the IMO's goal to cut carbon emissions by 40% relative to the 2008 level until 2030 and to reduce the total green house gas emissions of the shipping industry by 50% up to the year 2050. Fleet operators must therefore adapt their existing ships to the new requirements and retrofit appropriate systems. In view of the complexity of today's ship systems, the challenge is to identify solutions that are as efficient as possible, require only minor interventions in the existing ship structure and reduce emissions to a large extent.

As part of the ZAP (Zero Emission Auxiliary Propulsor) project, a new type of active rudder will be developed that can be retrofitted in place of the conventional rudder and, together with an electrification package, will enable zero-emission cruising. The active rudder is equipped with a ducted propeller and an electric motor integrated into the rudder, which offers additional operating capabilities. Among them, the propulsion of the vessel only by the active rudder, for slow transits or port approaches, where the main engine may be shut down. This will lead to considerable reductions in air pollution or noise emissions. In addition to that, the manoeuvrability at slow speeds is enhanced which increases the safety and operability in crosswind conditions. Such a retrofit is interesting for both cargo and passenger vessels. It can relieve port areas as the Elbe/Hamburg region and reduce the impact of shipping on ecologically sensitive areas such as the Geirangerfjord. The project includes extensive research activities based on numerous simulations for the development of the ZAP concept, with the aim of developing a fully functional product.

Our group is responsible for the hydrodynamic design and numerical modelling of manoeuvrability as well as estimations of the radiated underwater noise. Based on the institute's expertise in various disciplines of numerical modelling, intensive numerical simulations are carried out with RANS methods and with the in-house panMare boundary element method. The calculation results are compared with model tests during the development of the concept and with full-scale measurements in the later phases of the project. Furthermore, strength calculations and vibration estimations based on FEM simulations are carried out by the Institute for Ship Structural Design and Analysis. This cross-competence collaboration aims on the prediction of the structural behaviour and to gain insights into the fluid-structure interaction in the vicinity of working propulsors with a distinct focus on the radiated noise. In addition, the knowledge gained will be incorporated into a simplified design tool.


Project Acronym ZAP
Project Title Zero Emission Auxiliary Propulsor ZAP
Duration 2022-11-01 - 2025-05-31
Principal Investigator Moustafa Abdel-Maksoud

Jonathan Achstetter

Project partners


This project is funded by the Hamburgische Investitions- und Förderbank (IFB Hamburg).