2. MODEL EXPERIMENTS TO MEASURE HYDRODYNAMIC FORCES
The hull used for the experiments was an example of a modern escort tug hull developed by Robert Allan Ltd. of Vancouver, B. C (Allan et al. 2000). The hull is shown in Figures 1 and 2.
A summary of the model geometry is given in Table 1. For this series of experiments the model was always
moving with the fin (when fitted) going forwards (although the ship is actually going astern based on conventional definitions of bow and stern). This situation results from the fact that escort tugs have evolved from tractor tugs, which under normal operations sail with the propulsion system at the forward end of the hull. For effective escort mode at high speed, the tug operates in ‘indirect mode’, which is astern by the conventional definition.
0 10 9 6 7 8 1 2 3 5
Design Waterline
Figure 1, Body plan for tug model, used in PIV experiments.
Design Waterline
Figure 2, Profile view of tug, with fin and propulsion cage
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©2008: Royal Institution of Naval Architects
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