Making fast Tugboats make fast at about anywhere between 10 knots for escort duties and 6-8 knots for your general harbor approach. Now imagine making fast in the turbulent wake of a big sea-going vessel sailing at 8 knots and what effect this has on for example tugboats with big lateral underwater areas. A Rotor®Tug enables a tug master to make fast in between 5-7 minutes. Conventional tugboats with big lateral surface areas generally make fast in excess of 10 minutes. This doesn’t look like much, but the sea-going vessel moved some 750 meter ahead in the meantime. Ship turning Generally a ship calling at a port will enter the port under escort of tugboats before being turned in a turning basin and towed to its designated berth. Turning a ship before berthing generally enables simple un-berthing and sailing from a port after loading or discharging. Figure 2, Ship turning using push-pull
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The assisted vessel is turned by the turning couple (Bollard pull x Lever arm L) enacted by the assisting tugboats about its pivot point P;
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Lever arm L ↑ means increased turning moment = bollard pull effectiveness ↑;
Figure 3, Ship turning using full-pull
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Lever arm L ↑ 30% due to towing in the line instead of pushing on the designated tug area;
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Increased turning moment reduces turnaround time ↓ 30% and is an effective way to increase number of ship movements in fixed timeframes;
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A combination of figure 2 and figure 3 ship turning is also feasible dependent on: → local conditions (wind/current/under keel clearance/ jetty type or quay side structure) → vessel size
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