Session: 06-12-01 Ship Hydromechanics I

Paper Number: 103261

103261 - Reducing Containership Greenhouse Gas Emissions Through Speed Optimization by Coupling a Fast Time Manoeuvring Solver to a One-Dimensional Propulsion Model and Under Keel Clearance Prediction System in Shallow Water Under Environmental Forcings 

Deciding the target speed profiles within the harbour approach and navigational channels requires a trade-off between sufficient under-keel clearance and control of the ship under weather circumstances. The rudder as the main type of steering system for conventional ocean-going vessels is considered as a passive control device leading to decreased steering performance when ship speed through water decreases. On the shallow sections of navigational channels, the ship needs to slow down to maintain safe bottom clearance margins. However, once combined with strong wind or currents, this speed reduction may limit the ship's controllability and course-keeping which becomes a challenge to navigation.  In response to the recent pressures on the climate, another dimension has been added to this transit planning balance. It is now also important to optimize target speed profiles to minimize emissions while ensuring safety in maneuvering and reducing grounding risk. The emissions from the ship directly depend on the performance of the main propulsion system during the transit. A fast-time maneuvering solver using a PID controller for steering the ship is developed based on SimFlex 4 maneuvering model and linked to a one-dimensional model of the ship propulsion system to estimate the actual loading on the propeller and engine during the maneuvers. Consequently, the fuel consumption and emission of greenhouse gases from the engine are predicted. The ship under keel clearance is calculated based on the empirical squat, turning and wind-induced heel methods, and a second order panel method for evaluating vessel frequency response incorporating implicitly the effect of vessel forward speed and varying depth for the ship responses in waves. Consolidated as a commercial package, NCOS ONLINE, it is of the modern generation of operational tools for navigation optimization in shallow and confined waterways. The tool is then used to find the optimum target speed resulting in minimum emissions from the main propulsor, while the manoeuvring performance and under keel clearance remain within the acceptable thresholds for safe navigation of large containerships. The speed optimization tool is run on historic data of transits of similar containerships in the Port of Brisbane navigation channel for a full year and seems promising in terms of reducing shipping emissions in the port domain.

Keywords: emission, shipping, manoeuvring, propulsion, hydrodynamics.

Presenting Author: Reza Fathi Kazerooni Seaport OPX

Presenting Author Biography: Reza holds a PhD in Naval Architecture focused on manoeuvring and dynamic stability of high-speed crafts. He has submitted state-of-the-art publications in peer-reviewed international journals on ship manoeuvring and experimental methods for ship hydrodynamics in shallow and confined waterways and has 6 years of experience on novel designs of ship hulls and propulsion systems through working with an ITTC-recognized towing tank. Reza has assisted with the development of the NCOS ONLINE, Seaport OPX's (DHI Group) award-winning physics-based vessel response system providing operational and strategic decision support to all port stakeholders. NCOS ONLINE empowers port and maritime safety authorities to maximize both capacity and efficiency of marine assets, reduce CAPEX/OPEX, and always ensure safe operating conditions. Reza has a strong foundation in working on numerous navigation and channel capacity assessments worldwide.

Authors:

Reza Fathi Kazerooni Seaport OPX
Helena Karatvuo Seaport OPX
Alex Harkin Seaport OPX
Timothy Womersley Seaport OPX
Bugge Jensen Force Technology