Crabbing near Quays

Crabbing near Quays


From 2003 to 2006, a 3 years project was carried out, called COGNAC. This project succeeded in providing a practical software tool. This software tool enables the CRS Members to predict low speed manoeuvring and present low speed manoeuvring capability in a very meaningful way. Also, fundamental insight was obtained in the low speed manoeuvring phenomena.
The COGNAC Working Group has used one (representative) ship as a study object. The crabbing phenomena are studied for a podded, flap rudder and spade rudder arrangement. The developed theory and formulations are based on this study object.
There is a distinct wish to extend the capabilities, in particular for ‘near quay’ operations, but also to other (nautical) scenarios and other arrangements than the main study object up to now.

Left: open quay of San Diego Cruise Terminal – Right: closed quay of New Orleans Cruise Terminal


The major aim of the working group COGNAC2 is to understand the underlying principle of crabbing in the neighbourhood of the quay. Also more understanding of the influence of the hull form on crabbing is desired. In addition, the COGNAC tool will be elaborated and further distributed amongst the members.

Expected Results

  1. Knowledge and insight in crabbing
  2. Reports, including “Nautical procedures for crabbing” and “Summary report with insight in crabbing explained”
  3. Updated software tool