Kubla Ports Technical Manual
Channel widths are set based on the concept design method outlined in the PIANC Guidance and using the data which the user has input to define the site conditions and also in the properties of each channel element. The calculations are repeated with two design vessel speeds to determine the worst case.
The channel width for a given point along the channel is determined using the following expression for vessels where one-way traffic is specified:
w = wBM + Σwi + 2wB
...and with the following expression where two-way traffic is specified.
w = 2wBM + 2Σwi + 2wB + Σwp
Where wBM = basic manoeuvring lane, taken from the user-specified manoeuvrability for the vessel at the depth in question, using the following table:
| Vessel Manoeuvrability | Good | Moderate | Poor |
|---|---|---|---|
| wBM | 1.3B | 1.5B | 1.8B |
Where B is the beam of the design vessel
wi = additional widths, taken from the following table.
| Parameter | Value | Vessel Speed | Outer Channel | Inner Channel | ||
|---|---|---|---|---|---|---|
| Vessel speed (knots) | > 12 (Fast) | 0.1B | ||||
| 8 - 12 (Moderate) | 0.0 | |||||
| 5-8 (<8)(Slow) | 0.0 | |||||
| Prevailing cross wind (knots) | < 15 (Mild) | Fast | 0.1B | |||
| Mod | 0.2B | |||||
| Slow | 0.3B | |||||
| 15-33 (Moderate) | Fast | 0.3B | ||||
| Mod | 0.4B | |||||
| Slow | 0.6B | |||||
| 33-48 (>33) (Severe) | Fast | 0.5B | ||||
| Mod | 0.7B | |||||
| Slow | 1.1B | |||||
| Prevailing cross current (knots) | ≤ 0.2 (Negligible) | All | 0.0 | 0.0 | ||
| 0.2-0.5 (Low) | Fast | 0.2B | 0.1B | |||
| Mod | 0.25B | 0.2B | ||||
| Slow | 0.3B | 0.3B | ||||
| 0.5-1.5 (Moderate) | Fast | 0.5B | 0.4B | |||
| Mod | 0.7B | 0.6B | ||||
| Slow | 1.0B | 0.8B | ||||
| 1.5-2.0 (Strong) | Fast | 1.0B | - | |||
| Mod | 1.2B | - | ||||
| Slow | 1.6B | - | ||||
| Prevailing longitudinal current (knots) | ≤ 1.5 (Low) | All | 0.0 | |||
| 1.5-3.0 (Moderate) | Fast | 0.0 | ||||
| Mod | 0.1B | |||||
| Slow | 0.2B | |||||
| >3 (Strong) | Fast | 0.1B | ||||
| Mod | 0.2B | |||||
| Slow | 0.4B | |||||
| Bow and stern quartering Hs (m) | Hs ≤ 1 (irrespective of direction) | 0.0 | 0.0 | |||
| 1 < Hs < 3 (irrespective of direction) | ≈0.5B (0.5B) | - | ||||
| Hs ≥ 3 (irrespective of direction) | ≈1.0B (1.0B) | - | ||||
| Aids to Navigation | Excellent | 0.0 | ||||
| Good | 0.2B | |||||
| Poor | 0.4B | |||||
| Bottom Surface | Depth ≥ 1.5 T | 0.0 | ||||
| Depth < 1.5 T | ||||||
| - Smooth and soft (Mud or Sand/Clay) | 0.1B | |||||
| - Rough and hard (Rock/Coral) | 0.2B | |||||
| Depth of Waterway | ≥ 1.5T | 0.0 | ≥ 1.5T | 0.0 | ||
| 1.5T-1.25T | 0.1B | 1.5T-1.15T | 0.2B | |||
| <1.25T | 0.2B | <1.15T | 0.4B | |||
Where T = vessel draft and Hs = Significant wave height, and fast is > 12 knots, moderate is 8-12 knots, and slow is < 8 knots
wB = additional width for bank clearance, taken from the table below, based on Table 3.6 of the PIANC guidelines (guideline values in black, values used by software are highlighted)
| Vessel Speed | Additional Width | |
|---|---|---|
| Gentle underwater channel slope (1:10 or less steep) (Slope ≥ 1:10) | Fast | 0.2B |
| Moderate | 0.1B | |
| Slow | 0.0 | |
| Sloping channel edges and shoals (Slope ≥ 1:2) | Fast | 0.7B |
| Moderate | 0.5B | |
| Slow | 0.3B | |
| Steep and hard embankments, structures (Slope > 1:2) | Fast | 1.3B |
| Moderate | 1.0B | |
| Slow | 0.5B |
Where fast is > 12 knots, moderate is 8-12 knots, and slow is < 8 knots
wp = additional width for passing distance, taken from Table 3.7 of the PIANC guidelines.
| Vessel speed (knots) | Outer Channel | Inner Channel |
|---|---|---|
| Fast | 2.0B | 1.8B |
| Moderate | 1.6B | 1.4B |
| Slow | 1.2B | 1.0B |
In addition to this, 0.5B is added to the additional width for passing distance in the case of heavy traffic (>3 design vessels / day)