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Research Papers: Ocean Engineering

Tow Forces for Emergency Towing of Containerships

[+] Author and Article Information
Vladimir Shigunov

DNV GL SE,
Hamburg 20457, Germany
e-mail: vladimir.shigunov@dnvgl.com

Thomas E. Schellin

DNV GL SE,
Hamburg 20457, Germany
e-mail: thomas.schellin@dnvgl.com

1Corresponding author.

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received June 26, 2014; final manuscript received May 20, 2015; published online July 3, 2015. Assoc. Editor: Solomon Yim.

J. Offshore Mech. Arct. Eng 137(5), 051101 (Oct 01, 2015) (8 pages) Paper No: OMAE-14-1070; doi: 10.1115/1.4030688 History: Received June 26, 2014; Revised May 20, 2015; Online July 03, 2015

For a series of five containerships of differing capacities (707, 3400, 5300, 14,000, and 18,000 TEU), systematic computations were performed to estimate the tow force required in an emergency. Time-average ship positions with respect to the given waves, wind, and current directions and the corresponding time-average forces were considered. Current speed was considered to include also towing speed. Directionally aligned as well as not aligned wind and waves were investigated. Wave height, wind speed, and wave and wind direction relative to current direction were systematically varied. Wind speeds based on the Beaufort wind force scale corresponded to significant wave heights for a fully arisen sea. Waves were assumed to be irregular short-crested seaways described by a Joint North Sea Wave Observation Project (JONSWAP) spectrum with peak parameter 3.3 and cosine squared directional spreading. For each combination of current speed, wave direction, significant wave height, and peak wave period, the required tow force and the associated drift angle were calculated. Tow force calculations were based on the solution of equilibrium equations in the horizontal plane. A Reynolds-Averaged Navier–Stokes (RANS) solver obtained current and wind forces and moments; and a Rankine source-patch method, drift forces and moments in waves. Tow forces accounted for steady (calm-water) hydrodynamic forces and moments, constant wind forces and moments, and time-average wave drift forces and moments. Rudder and propeller forces and towline forces were neglected.

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References

Harding, S., Pearse, J., and Riding, J., 2008, “Emergency Towing Vessels Assessment of Requirements,” The Maritime and Coastguard Agency, Southampton, UK, Final Report UK MCA 258 (ETV).
IMO, 1998, Guidelines for Safe Ocean Towing, International Maritime Organisation, London, UK, Secs. 6 and 9.4.
Sanders, R. E., and Shepherd, W. D., 1998, The Practice of Ocean Rescue, Brown, Son & Ferguson, Nautical Press, Glasgow, UK, Chap. 1.
Sinibaldi, M., Bulian, G., and Francescutto, A., 2013, “A Nonlinear Dynamics Perspective on Some Aspects of Towing Operations Relevant to Safety and Energy Efficiency,” First International Conference IDS2013—Amazonia, Iquitos, Peru, July 17–19, pp. 05-1–05-16.
Bernitsas, M. M., and Kekrides, N. S., 1985, “Simulation and Stability of Ship Towing,” Int. Shipbuild. Prog., 32(369), pp. 112–123.
Schellin, T. E., 2003, “Mooring Load of a Ship Single-Point Moored in a Steady Current,” J. Mar. Struct., 16(2), pp. 135–148. [CrossRef]
Sharma, S. D., Jiang, T., and Schellin, T. E., 1994, “Nonlinear Dynamics and Instability of SPM Tankers,” Fluid Structure Interaction in Offshore Engineering, S. K.Chakrabarti, ed., Computational Mechanics Publications, Southampton, UK, pp. 85–123.
Myers, J. J., Holm, C. H., and McAllister, R. F., eds., 1969, Handbook of Ocean and Underwater Engineering, McGraw-Hill Book, New York, pp. 97–99.
CD-adapco, 2011, STAR-CCM+ User Guide 6.02.007, CD-adapco, Nuremburg, Germany.
Söding, H., Shigunov, V., Schellin, T. E., and el Moctar, O., 2012, “A Rankine Panel Method for Added Resistance of Ships in Waves,” ASME J. Offshore Mech. Arct. Eng., 136(3), p. 031601. [CrossRef]
Pinkster, J. A., 1980, Low Frequency Second Order Wave Exciting Forces on Floating Structures, Netherlands Ship Model Basin, Wageningen, The Netherlands, p. 95.
el Moctar, O., Schellin, T. E., and Priebe, T., 2006, “CFD and FE Methods to Predict Wave Loads and Ship Structural Response,” 26th Symposium on Naval Hydrodynamics, Rome, Italy, Sept. 17–22, pp. 333–351.
U. S. Navy, 1988, Towing Manual SL 740-AA-MAN-010 Rev. 1, Naval Sea Systems Command, Washington, DC, Chap. 6, Appendix G, Sec. G-1, Item 18.

Figures

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Fig. 1

Coordinate systems and definitions for towed ships

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Fig. 7

Layout of the 14,000 TEU containership towed in collinearly acting wind and waves of hs = 1.5 m (left) and 3.0 m (right)

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Fig. 9

Layout of the 14,000 TEU containership towed in wind deviated 30 deg counterclockwise from waves of hs = 1.5 m (left) and 3.0 m (right)

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Fig. 12

Layout of the 14,000 TEU containership towed in wind deviated 30 deg clockwise from waves of hs = 4.5 m (left) and 6.0 m (right)

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Fig. 2

Nondimensional hydrodynamic calm-water force and moment coefficients X's, Y's, and N's versus drift angle β (deg) for the 14,000 TEU containership

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Fig. 3

Nondimensional aerodynamic wind force and moment coefficients X'w, Y'w, and N'w versus apparent wind angle of attack ε (deg) for the 14,000 TEU containership

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Fig. 4

Quadratic transfer functions of (from top to bottom) longitudinal drift force Fx/ζa2 (N/m2), lateral drift force Fy/ζa2 (N/m2), and yaw drift moment Mz/ζa2 (N m/m2) versus wave frequency ω (rad/s) for a single-point moored tanker in bow-quartering waves from Germanischer Lloyd (GL) Rankine computations (lines) and experiments (symbols)

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Fig. 5

Maximum tow force Ft (t) over all primary wave directions versus significant wave height hs (m) for the 14,000 TEU containership in collinearly acting wind and waves (solid line) and in wind deviating by 30 deg (dashed line) and −30 deg (dash-dotted-dotted line) from the primary wave direction

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Fig. 6

Maximum tow force Ft (t) over all wave directions versus significant wave height hs (m) for 707 (lower solid line), 3400 (dashed line), 5300 (dash-dotted line), 14,000 (dash-dotted-dotted line), and 18,000 (upper solid line) TEU container ships

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Fig. 8

Layout of the 14,000 TEU containership towed in collinearly acting wind and waves of hs = 4.5 m (left) and 6.0 m (right)

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Fig. 10

Layout of the 14,000 TEU containership towed in wind deviated 30 deg counterclockwise from waves of hs = 4.5 m (left) and 6.0 m (right)

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Fig. 11

Layout of the 14,000 TEU containership towed in wind deviated 30 deg clockwise from waves of hs = 1.5 m (left) and 3.0 m (right)

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