Discussing the effect of propeller turning direction on manoeuvring and course keeping (MORE project)

to their advantage and had knowledge that their competitors did not have.

Which applied research did CRS perform? CRS established a working group with a budget to investigate these issues. CRS members needed to know what it would take to reach acceptable stopping distances. The loads that acted on the propeller were very unconventional during stopping manoeuvres. Research took place while measuring the strength of the propellers, and the rapid change of the turning direction of the engine. The Manoeuvring in Early Design Stage working group (1988-1991) and the MAN working groups (1992-1996) focused on the possibility of predicting the cross-flow drag coefficients using segmented model test results.

28 report

Segmented model tests were carried out to obtain insight into the distribution of manoeuvring forces over the length of a ship. Re-analysis of existing segmented model tests of the so-called ‘Todd series’ formed the start of the MPP program. Testing of the first version of MPP revealed a good correlation for most ships, except modern tanker forms which had the ‘pram’ stern. To correct for this, a modern tanker hull was selected to conduct further segmented model tests. This hull form was both lengthened and shortened so that data for different hull forms became available. Hydrodynamicists such as Geert Kapsenberg, Jan Hooft, Ian Dand and Wim Beukelman performed groundbreaking investigations and set-up the cross flow drag method to quantify the non-linear manoeuvring forces. At that time, this was unconventional, but

the scientists were convinced that they were on the right track. While somewhat quirky, this has resulted in improvements that otherwise would not have been possible. And it has led to a practical and robust tool for CRS members!

Since 1990, the following working groups have all played a role:

• LB: tankers in light ballast conditions • MED: manoeuvring in early design • RUD: rudder design manual • MAN: manoeuvring predictions • MANTS: manoeuvring for twin screw vessels • MAN3: manoeuvring predictions for podded vessels

• COGNAC: low speed manoeuvring (crabbing)

• COGNAC-2: crabbing in the neighbourhood of quays

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