Ship Assist in Fully Exposed Conditions - Joint Industry Project SAFETUG
Author Johan H de Jong
Title Ship Assist in Fully Exposed Conditions - Joint Industry Project SAFETUG
Conference/Journal Tugnology
Paper no. 2
Month June
Year 2007

Abstract
SAFETUG Joint Industry Project (JIP) gathered almost 30 participants who jointly studied the performance and behaviour of tugs in waves while assisting at very slow speed (berthing), slow speed (escorting direct assist) or high speed (escorting indirect assist). The data on performance and behaviour is used to define the operability during berthing and escorting operations. The operability determines the downtime of certain operations critical for the economic viability. The performance aspects in waves covered propulsion efficiency, direct and indirect assist capabilities and pushing capabilities. Behavioural aspects focussed on dynamic towline forces, required winch response, extreme tug motions (primarily roll and yaw) and the identification of the operational criteria for the various modes of operation. The extreme tug motions and criteria definition focussed on the human safety and workability issues of tug operation. The project took as a reference a representative Azimuthing Stem Drive (ASD) design and a representative Voith Water Tractor (VWT) design. The latter could be seen as comparable with Azimuthing Water Tractor (AWT). The most important means to determine the performance and behaviour of the tugs is done through model testing and limited model definition. Operability methodologies were defined, which used the collected data to settle the relevant model aspects.
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