Estimation of Effective Wave Slope Coefficient of Ships with Large Breadth and Draught Ratio

*Daeng Paroka scopus  -  Department of Ocean Engineering, Faculty of Engineering, Hasanuddin University, Indonesia
Andi Haris Muhammad  -  Departement of Marine System Engineering, Faculty of Engineering, Hasanuddin University, Indonesia
Sabaruddin Rahman  -  Department of Ocean Engineering, Faculty of Engineering, Hasanuddin University, Indonesia
Received: 2 Feb 2020; Revised: 26 Feb 2020; Accepted: 26 Feb 2020; Published: 29 Feb 2020; Available online: 29 Feb 2020.
Open Access License URL: https://creativecommons.org/licenses/by-sa/4.0/

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Section: Research Articles
Language: EN
Statistics: 1221 174
Abstract
One of parameters to estimate heel angle of a ship in beam seas is effective wave slope coefficient. In the weather criterion of IMO, the effective wave slope coefficient is determined as function of ratio between distance of center of gravity from the sea surface and the ship draught. The others methods could be used to estimate the effective wave slope coefficient are simplified strip theory and model experiment. A ship with shallow draught and large vertical center of gravity can have an effective wave slope coefficient larger than 1.0 if the coefficient is calculated by using the formulae of weather criterion. Therefore, an alternative method to estimate the coefficient is necessary when it is applied to ships with geometry characteristics different with those used to develop the formulae. This research conducts to estimate the effective wave slope coefficient using three different methods, namely the formulae of weather criterion, the simplified strip theory and model experiment. Results of the three methods may provide enough evidence about suitable method to estimate the effective wave slope coefficient of ships with breadth and draught ratio larger than 3.5 like the Indonesian ro-ro ferries. Results and discussion show that the effective wave slope coefficient obtained by using the formulae of weather criterion is larger compared to that obtained by using the simplified strip theory and the model experiment. Here, the result of simplified strip theory for wave frequency the same as the roll natural frequency of subject ship is similar with the result of model experiment. This results show that the simplified strip theory can be used as an alternative method to determine the effective wave slope of a ship with breadth and draught ratio larger than 3.5 if the result of model experiment does not available.
Keywords: ship stability; weather criteria; wave slope coefficient; ro-ro ferry

Article Metrics:

  1. I. M. O. Resolution, “267 (85)-adoption of the international code on intact stability.” London, UK: IMO Publishing, 2008.
  2. A. Francescutto, A. Serra, and S. Scarpa, “A critical analysis of weather criterion for intact stability of large passenger vessels,” in OMAE 2001, 2001, pp. 1–8.
  3. S. Ishida, H. Taguchi, and H. Sawada, “Evaluation of the Weather Criterion by Experiments and its Effect to the Design of a RoPax Ferry,” in Contemporary Ideas on Ship Stability and Capsizing in Waves, Springer, 2011, pp. 65–78.
  4. Y. Sato, H. Taguchi, M. Ueno, and H. Sawada, “An experimental study of effective wave slope coefficient for two-dimensional model,” in 6th Osaka Colloquium on Seakeeping and Stability of Ships (OC2008), 2008.
  5. A. Francescutto, “Intact stability criteria of ships--Past, present and future,” Ocean engineering, vol. 120, pp. 312–317, 2016.
  6. IMO, “Finalization of Second Generation Intact Stability Criteria: Information Collected by the Correspondence Group on Intact Stability Regarding Second Generation Intact Stability Criteria,” in Document SDC 3/INF.10 Submitted by Japan, 2015.
  7. S. Rudaković, G. Bulian, and I. Bačkalov, “Effective wave slope coefficient of river-sea ships,” Ocean Engineering, vol. 192, p. 106427, 2019.
  8. IMO, “Interim Guidelines for Alternative Assessment of Weather Criterion,” in Document MSC.1/Circ.1200, 2006.
  9. IMO, “Development of Second-Generation Intact Stability Crtieria: Vulnerability Assessment for Dead-Ship Stability Failure Mode,” in Document SDC 1/INF.6 Submitted by Italy and Japan, 2013.
  10. D. Paroka, “Karakteristik geometri dan pengaruhnya terhadap stabilitas kapal ferry ro-ro Indonesia,” Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan, vol. 15, no. 1, pp. 1–8, 2018.
  11. F. Tasai and M. Takagi, “Theory and Calculation Method for Response in Regular Waves (in Japanese),” in The Seakeeping Symposium, Society of Naval Architects of Japan, 1969.
  12. ITTC, “Numerical Estimation of Roll Damping: Recommended Procedures,” in The 26th ITTC Specialist Committee on Stability in Waves, 2011.
  13. R. Borisov, A. Luzyanin, M. Kuteynikov, and V. Samoylov, “An approach to assess the excessive acceleration based on defining roll amplitude by Weather Criterion formula with modified applicability range,” Proceedings of STAB, pp. 601–612, 2015.
  14. D. Paroka, S. A. Rosmani, and Hamzah, “Alternative Assessment of Weather Criterion for Ships with Large Breadth and Draught Ratios by Model Experiment: A Case Study on an Indonesian Ro-Ro Ferry,” International Journal of Maritime Engineering, 2019.
  15. G. Bulian and A. Francescutto, “A simplified modular approach for the prediction of the roll motion due to the combined action of wind and waves,” Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, vol. 218, no. 3, pp. 189–212, 2004.