Synergy between theory and practice for Ultra Large Containerships sailing to the port of Antwerp

In 2003 an accessibility study based on real-time simulations for the S-class container ships of Maersk Sealand was performed at Flanders Hydraulics Research in cooperation with all involved parties (public and port authorities, pilots, tug and shipping company). The regulation for the upstream and downstream navigation on the Western Scheldt did not accept the arrival of a ship with length over all greater than 340 m.The paper describes two main research studies executed to fill in the gap of knowledge about the manoeuvring behaviour of container ships in shallow and confined water: the accessibility of Ultra Large Container Ships with a maximum capacity of 14,000 TEU to the Western Scheldt and the accessibility of the Berendrecht Lock and Delwaide Dock located on the right bank of the port of Antwerp. An integrated simulation platform with mathematical models describing hydrodynamic (manoeuvrability, ship-bank and ship-ship interaction) and external (wind, current, tug assistance) forces and coupled ship manoeuvring simulators helped in evaluating the possibilities and limitations of head-on encounters, lock and turning manoeuvres.The combination of research and training has finally led to the arrival of the MSC Beatrice in April 2009. After a validation period of more than half a year, characterised by a constant adaptation of negotiated restrictions, a new regulation for the upstream and downstream navigation is being prepared

Development of a test program for the prediction of ship manoeuvrability in deep and shallow water

As in many coastal and estuary areas, navigation to and in the Belgian harbours takes place in environmental and operational conditions which differ from the design conditions of sea-going ships: water depth to draft ratios vary between 2.0 and 1.1 which means that the under keel clearance is often restricted to 10% of the ship’s draft. In addition, low ship velocities have to be considered as manoeuvring in harbour areas is characterised by a wide range of speed - propeller rpm combinations. Based on the results of captive model tests executed in the Towing Tank for Manoeuvres in Shallow Water (co-operation Flanders Hydraulics Research - Ghent University, Antwerp, Belgium) with a 6000 TEU containership and the tanker Esso Osaka, an optimized test program has been developed for the determination of a mathematical manoeuvring model in later-ally unrestricted water. Contrary to deep water and service speed the selected test types and test parameters will influence the measured contributions of the modules hull, propeller and rudder in shallow water: as an example, stationary oblique towing and harmonic sway tests may lead to dif-ferent results, while the reliability of the test results is much more sensitive to the selected test pa-rameters during PMM tests. Due to the reduced under keel clearance even unusual phenomena may occur

Probabilistic regulation for inland vessels operating at sea as an alternative hinterland connection for coastal harbours

In 2007, the Belgian Federal Authorities issued a Royal Decree concerning “inland vessels that can also be utilised for non-international sea voyages”, allowing inland vessels to operate in coastal areas between the Belgian coastal harbours and the Belgian inland waterway network via the Western Scheldt. These new regulations have a unique character due to their probabilistic approach: among other requirements, a risk analysis must demonstrate that the probability of adverse events such as bottom slamming, overtaking of water on deck and ingress of water in open cargo holds is limited to an acceptable level. Several inland vessels (tankers, container vessels, car carriers) are nowadays operating according to this Decree in significant wave heights up to 1.90 m. Background is provided into these present regulations, with emphasis on the probabilistic aspects. A description is given of the methodology used for performing the required risk analyses. The effect of important parameters is discussed, both ship related (metacentric height, bilge keels) and wave climate dependent, and an overview of the ongoing research at Flanders Hydraulics Research and Ghent University on estuary container vessels is given

Estuary traffic: an alternative hinterland connection for coastal ports

In 2007, the Belgian Federal Authorities issued a Royal Decree concerning "inland vessels that can also be utilised for non-international sea voyages", allowing inland vessels to operate in coastal areas between the Belgian coastal harbours and the Belgian inland waterway network via the Western Scheldt, provided that – among other requirements – a risk analysis demonstrates that the probability of adverse events such as bottom slamming, overtaking of water on deck and ingress of water in open cargo holds is limited to an acceptable level. Several tankers and container vessels are nowadays operating in significant wave heights up to 1.90 m. The present paper intends to provide background into the present regulations, to describe the methodology used for performing risk analyses, and give an overview of the present and future research at Flanders Hydraulics Research and Ghent University on estuary container vessels

A methodology for evaluating the controllability of a ship navigating in a restricted channel

A methodology is presented for evaluating the controllability of a ship navigating in a restricted channel by means of a hydrodynamic force analysis. This method is applied to assess the controllability of a container vessel in straight channel reaches and in bends in two practical cases. By comparing different initial conditions and bottom configurations the influence of different ship characteristics (main dimensions, draft, rudder and propeller characteristics), operational parameters (such as speed, propeller commands, and bank clearance), environmental parameters (such as current and tidal level), and channel characteristics (water depth, bank slope, bend radius) on this controllability can be evaluated. For estimating the components of the force analysis, use is made of results of captive model tests in shallow and restricted waters

An overview of squat measurements for container ships in restricted water

Squat is an important issue for ships navigating with limited under keel clearance in restricted waterways such aschannels and canals. The admittance policy for containerships on the Western Scheldt, a tidal estuary in theNetherlands giving access to the port of Antwerp (Belgium), is based on a minimal static under keel clearance toensure safe passages on the river. A large number of captive model tests executed in the Towing Tank forManoeuvres in Shallow Water (co-operation Flanders Hydraulics Research - Ghent University) have beenevaluated to determine squat prediction formulae. Measured sinkage and trim depend on a number of parameterslike ship velocity components, ship loading condition, propeller action, blockage of the waterway, bankgeometries and characteristics of other shipping traffic. The derived mathematical models have beenimplemented in the ship manoeuvring simulators of FHR to visualize the dynamic under keel clearance duringreal-time simulations at different locations on the Western Scheldt

Validation of ship manoeuvring in shallow water through free-running tests

The shallow water effect on ship manoeuvring cannot be neglected. Most sea-going ships become more course stable when they sail from deep to (very) shallow water. International collaborations such as SIMMAN intend to grade up the knowledge on ship manoeuvring prediction through model tests and system based and numerical methods. Free-running model tests executed with the very large crude carrier KVLCC2 at two laboratories have been compared with the results of simulated turning circles and zigzag manoeuvres from two different mathematical models.It was concluded that the type of mathematical model has an important influence on the simulated behaviour. Moreover, further research is necessary as simulations result into a more course stable behaviour compared to free-running tests at model scale

Prediction of low speed manoeuvring based on captive model tests: opportunities and limitations

The Flemish waterways authorities are permanently concerned about safety of navigation to the Belgian harbours in order to maintain their present position in the European shipping market Special attention is paid to the effect of the constant growth of ship dimensions, especially in the container traffic, to safe shipping traffic. Harbour manoeuvres are characterised by a great diversity and particularly tow speed manoeuvring is brought more and more to the attention of the institutes involved in the prediction of ship manoeuvrability. Hydrodynamic forces induced at low speed and low or even reversed telegraph positions must be determined carefully both in deep and in shallow water. Some insight into the opportunities and limitations of mathematical modelling based on captive model tests could be obtained based on a thorough investigation started at Flanders Hydraulics Research. This paper will focus on results of model tests with a fourth generation containership with a draught of 15.0 m at an under keel clearance of 20%