# Effect of bilge keels on maneuverability of a fine ship

- 74 Downloads

## Abstract

This paper discusses the effect of bilge keels on maneuverability of a fine ship experimentally and theoretically. To capture the effect, first, free-running model tests were conducted using a KCS container ship model with detachable bilge keels. We found that bilge keels improve the turning performance and enlarge overshoot angles in zig-zag maneuvers, and that this tendency becomes more pronounced with increasing ship speed. Next, captive model tests were conducted to capture the hydrodynamic forces’ effects on maneuvering to clarify the reason for the difference in maneuvering in the presence of bilge keels. By attaching bilge keels, the absolute values of \(Y_v'\), \(N_v'\), and \(K_v'\) (the linear derivatives of lateral force, yaw moment, and roll moment acting on the ship with respect to lateral velocity *v*, respectively) are increased and \(Y_{\phi }'\) (the derivative of the lateral force with respect to roll \(\phi\)) is also increased. It can be explained theoretically that the change of the hydrodynamic derivatives leads to course instability according to the course stability criterion presented by Yasukawa and Yoshimura [3]. The special feature of the criterion is to include the roll-coupling effect. Thus, the roll-coupling significantly affects ship maneuverability through hydrodynamic derivative changes by attaching bilge keels to fine ships with small metacentric height \(\overline{GM}\).

## Keywords

Bilge keels Ship maneuverability Captive model tests Free running tests Course stability## Notes

### Acknowledgements

This study was inspired through discussions with Dr. F. Quadvlieg of the Maritime Research Institute Nederland (MARIN), and we would like to express our thanks to him. We would like to extend our thanks to Dr. A. Matsuda and Dr. D. Terada of the National Research Institute of Fisheries Engineering, Japan, and Mr. S. Mizokami and Mr. R. Kuroiwa and their staff of the Seakeeping and Maneuvering Basin at the Nagasaki R & D Center, Mitsubishi Heavy Industries, for their help with the tank tests. This study was supported by JSPS KAKENHI Grant no. JP26249135.

## References

- 1.Karimata T (1974) Effect of the bilge keel on the maneuverability of ship. Mem Fac Fish Kagoshima Univ 23:71–80 (
**in Japanese**)Google Scholar - 2.Dubbioso G, Durante D, Broglia R, Mauro S (2012) Comparison of experimental and CFD results for a tanker like vessel. In: International Conference on Marine Simulation and Ship Maneuverability (MARSIM’12), Singapore (2012), USB MemoryGoogle Scholar
- 3.Yasukawa H, Yoshimura Y (2014) Roll-coupling effect on ship maneuverability. Ship Technol Res 61(1):16–32Google Scholar
- 4.Part B: Benchmark Test Cases, KCS Description, SIMMAN (2008) Workshop on verification and validation of ship manoeuvring simulation method, Workshop Proceedings, Vol 1 Copenhagen, Denmark, pp B11–B14Google Scholar
- 5.Miyazaki H, Tsukada Y, Takimoto T (2013) Experimental study about the effect of the container ship’s metacenter height on the manoeuvrability, Conference Proceedings, The Japan Society of Naval Architects and Ocean Engineers, Vol 16, Paper no.2013S-OS1-6 (
**in Japanese**)Google Scholar - 6.Fukui Y, Yokota H, Yano H, Kondo M, Nakano T, Yoshimura Y (2016) 4-DOF mathematical model for manoeuvring simulation including roll motion. J Jpn Soc Naval Archit Ocean Eng 24:167–179 (
**in Japanese**)Google Scholar - 7.Hamamoto M, Kim Y-S (1993) A new coordinate system and the equations describing manoeuvring motion of a ship in waves. J Soc Naval Archit Jpn 173:209–220 (
**in Japanese**)CrossRefGoogle Scholar - 8.Lewandowski EM (2003) The dynamics of marine craft: maneuvering and seakeeping. World Scientific Publishing Co. Inc, Hackensack (
**ISBN-10: 9810247560**)Google Scholar - 9.Yasukawa H, Yoshimura Y (2015) Introduction of MMG standard method for ship maneuvering predictions. J Mar Sci Technol 20(1):37–52CrossRefGoogle Scholar
- 10.Yasukawa H, Sano M (2008) Maneuvering simulation of MOERI container ship, SIMMAN 2008, Workshop on verification and validation of ship manoeuvring simulation methods, Workshop Proceedings, Vol 1, Copenhagen, Denmark, pp E68–E73Google Scholar
- 11.Fujii H, Tuda T (1961) Experimental research on rudder performance (2). J Soc Naval Archit Jpn 110:31–42 (
**in Japanese**)Google Scholar