Q&A: Hydrodynamics and energy efficiency improvements

Shipowners are increasingly exploring hydrodynamic efficiency improvements – including Energy Saving Devices (ESDs) and hull-form retrofits – to cut fuel consumption, improve CII performance and strengthen short-term returns on existing tonnage. With fuel prices and emissions pressure rising – and the IMO’s Net Zero Framework delayed by a year – many owners are focused on keeping existing tonnage compliant and economically competitive for as long as possible before committing to new fuels and newbuilds.

When correctly applied, targeted hydrodynamic upgrades can deliver 5-15% propulsion savings, sometimes more, with payback periods measured in months rather than years. At the same time, the performance of such measures is highly vessel-specific. Results depend on geometry, operating profile, propulsion arrangement and historical design constraints, making case-specific CFD analysis and commercial screening essential.

In this 10-question Q&A, Head of R&D Mia Elg, together with Head of Hydrodynamics Matias Niemeläinen and naval architects Juho Suortti and Aki Ruohonen, explain where retrofit potential is typically found, which ESD concepts deliver reliable real-world savings, how projects move from CFD to steel-in-water, how results are validated in service and when it makes commercial sense not to proceed.

The perspective reflects Deltamarin’s holistic approach to hydrodynamic optimization, where performance is evaluated as part of the vessel’s wider propulsion and operational system – ensuring improvements are technically sound, commercially defensible and well-timed for a fleet in transition.