Tug Use in Port - Cap 4 Tug Capabilities and Limitations

4.1 -Introduction
4.2 - Basic priciples and definitions
1. 4.2.1 - Pivot Pint
2. 4.2.2 - Towing point, pushing point and lateral centre of pressure. Direct Towing and indirect towing. Skegs
  1. The lateral centre of pressure
  2. The lateral centre of pressure
  3. Direct and indirect towing method
  4. Pushing point
  5. Skeg and their effect
3. 4.2.3 Stability
  1. High GM and good dynamic stability
  2. Reducing transverse resistance of the hull
  3. Reducing de height of the towing point
  4. Reducing the height of the pushing point
  5. A towline with good shock absortion characteristics
  6. Tug freeboard being such that the deck edge is not immersed at too small a heeling angle
4.3 - Capabilities and limitations
1. 4.3.1 Capabilities and limitations of the tug
  1. Tugs towing on a line
    1. forward tugs towing on a line
    2. Stern tugs towing on a line
  2. Tugs opeting at a ship`s side
    1. Pushing mode
    2. Pulling mode
    3. Stopping assistance
  3. Summary
    1. Conventional tugs
    2. Tractor and Reverse-tractor tugs
    3. ASD tugs
2. 4.3.2 Effectiveness of tug types
  1. Performance diagrams
    1. Performance of a conventional and ASD-tug when pushing at a ship underway at speed
    2. Performance of a ASD and VS tug while towing on a line
  2. Speed control - braking assistance
3. 4.3.3 Effective tug position
4. 4.3.4 Towing on a line compared with operating at a ship`s side
4.4 - Operational limits
4.5 - Design consequences
4.6 - Conclusions regarding tug types
4.7 - Some other pratical aspects
1. Coperation
2. Communications between pilots and tug captains
3. Tug use
4. Speed
5. Decreasing effectiveness of tugs when a ship gathers speed
6. Ship´pulled or pushed around by a bow tug gathers speed

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Tug Use in Port - Cap 4 Tug Capabilities and Limitations

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	Created by Hegner Machado almost 8 years ago