The impact of muddy bottoms in ports

ABSTRACT

Ports are drivers of regional and of countries’ economic development. Most ports are built close to coastlines, where waters are shallower and tend to suffer from deposit sedimentation processes, which reduce depths in operational areas. In presence of shallow waters and sedimentation, ports must decide whether to dredge or not, where both decisions have significant impacts on ports’ annual incomes. Nevertheless, there are seabeds, namely muddy bottoms, in which vessels can navigate with a safety degree. This paper aims at investigating the extent to which the theoretical knowledge of vessel’s control in muddy waters is valid at a certain nautical bottom, as defined by the Permanent International Association of Navigation Congresses (since 2009 the World Association for Waterborne Transport Infrastructure but the acronym stays PIANC) and its impact on port economics. To achieve the proposed objective, an email survey was sent to worldwide pilots that manoeuvre ships in muddy waters. The survey validated the theoretical knowledge, showed that navigation in muddy waters is possible, that it can contribute to reduce ports’ operational costs, and that the subject can be rather controversial.

KEYWORDS:

• Mud navigation
• sedimentation
• nautical bottom
• squat
• dredging

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Tanker (model L) = 310 m; B = 47.2 m; T = 18.9 m; C_B = 0.85, where being L length, B beam, T draught, and C_B coefficient of block.

2. 6000 TEU container carrier (model D): Lpp = 289.8 m; B = 40.25 m; T = 13.50 m; CB = 0.59.

3. Full-bodied ship (tanker/bulk carrier model E): Lpp = 286.8 m; B = 46.77 m; T = 15.50 m; CB = 0.82.

4. 8000 TEU container (model U): Lpp = 331.8 m; B = 42.8 m; T = 14.5 m; CB = 0.65; scale 1/80.

5. Post-Panamax model Jumbo: Lpp = 320 m; B = 40 m; T = 14.5 m; C_B = 0.74; UKC = 1–2 m.

6. Post-Panamax model Mega-Jumbo: Lpp = 360 m; B = 55 m; T = 15.5; C_B = 0.667, UKC = 1–1.5–2 m.

7. The tests were as follows: Type 1: acceleration/deceleration tests, Type 2: constant pitch (power), and Type 3: rotation of the ship at zero speed by means of bow thruster.

8. Hamburg Express Class ships 7506 TEU: Lpp 320.4 m, B = 42.8 m, T = 10.8–12.6 m, C_B = 0.62–0.65.

9. Yang Ming Shipping company 5500 TEU class: Lpp = 274.7 m, B = 40 m, T = 11.4–13.2 m, C_B = 0.56–0.59.