Development and validation of speed loss for a blunt-shaped ship in two rough sea voyages in the Southern Hemisphere

Sasa, Kenji; Faltinsen, Odd M.; Lu, Li-Feng; Sasaki, Wataru; Prpić-Oršić, Jasna; Kashiwagi, Masashi; Ikebuchi, Takuro

doi:10.1016/j.oceaneng.2017.07.029

Cited by 14 publications

(6 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The criteria for deliberate speed reduction proposed between 1960s and 1980s should be revaluated against contemporary data from practical marine environments. The authors of this paper in a separate study had already produced the results of performance analysis of the 28,000-DWT-class bulk carrier in the rough seas of the Southern Hemisphere (Sasa, et al, 2017). Hence, the validity of the criteria in this paper is shown with the measured data gathered from some rough sea voyages.…”

Section: Introductionmentioning

confidence: 74%

“…It is basically discussed for regular waves in frequency domain. In case of irregular sea state, the ship speed is decided by solving the following equations in frequency and time domain (Sasa, et al, 2017).…”

Section: Analysis Methods Of Measured Datamentioning

confidence: 99%

“…The relative wave direction should be constant in each data unit. According to the former research (Sasa et al, 2017), the relative wave direction varies every 10-30 min. in rough sea conditions.…”

Section: Analysis Methods Of Measured Datamentioning

confidence: 99%

“…The validity of parameters discussed in previous sections is considered for the measured data of the 28,000-DWT-class bulk carrier in actual seas (Sasa, et al, 2015;Sasa, et al, 2017;Lu, et al, 2017). The measurement was conducted from July 2010 to August 2016, with periods of missing data in between because of mechanical troubles.…”

Section: Onboard Measured Data In Actual Seamentioning

confidence: 99%

See 3 more Smart Citations

Evaluation of speed loss in bulk carriers with actual data from rough sea voyages

et al. 2019

Self Cite

View full text Add to dashboard Cite

The evaluation of speed loss is the most important studies in the optimal ship routing. However, the mode of speed loss during rough sea voyages is complicated because of the involvement of the human factor. A speed loss analysis is conducted to improve the accuracy of evaluation of measured data extracted from actual marine conditions. First, the conventional criteria to judge the deliberate speed reduction is summarized with the conventional ship maneuvering techniques. Second, a nationwide questionnaire for marine engineers implemented for engine safety during rough sea voyages is detailed. Third, these conventional criteria are validated by analyzing the collated data on accelerations, ship motions, navigation, and engine parameters. The limiting value of vertical acceleration agrees with that obtained via practical measurements. On the contrary, the limiting values of lateral acceleration, roll motions, probabilities of deck wetness, and slamming do not agree with that obtained via measurements. The probabilities of deck wetness, slamming, and propeller racing start to increase at approximately the same instant where the deliberate speed reduction occurs. Some relations between the deck and engine parameters detailed in this paper were found to be highly correlated. Finally, the results of the analysis were used to model simpler estimations.

show abstract

Section: Introductionmentioning

confidence: 74%

Section: Analysis Methods Of Measured Datamentioning

confidence: 99%

Section: Analysis Methods Of Measured Datamentioning

confidence: 99%

Section: Onboard Measured Data In Actual Seamentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of speed loss in bulk carriers with actual data from rough sea voyages

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The difference in estimated ship motion reflects on both involuntary and voluntary speed reduction. Lu et al [14] and Sasa et al [15] have analyzed three extreme cases of bulkcarrier sailing during storms at Southern Hemisphere. They reproduced the environment by three different wind inputs with various spatial and temporal resolutions.…”

Section: Uncertainty Of Seakeeping Analysis and Operating Factorsmentioning

confidence: 99%

Uncertainties of Ship Speed Loss Evaluation Under Real Weather Conditions

Prpić-Oršić

Sasa

Valčić

et al. 2020

Journal of Offshore Mechanics and Arctic Engineering

Self Cite

View full text Add to dashboard Cite

A correct assessment of the ship speed loss in conditions of operation is becoming increasingly important for ship owners as well as ship designers. We are witnessing increasing concern for the environment and awareness of the necessity to preserve it as much as we could. The ship speed drop in the real environmental conditions can cause increased fuel consumption as well as increased emissions of CO2 and other greenhouse gases (GHGs) from ships. Decrease in the ship speed in real conditions is a consequence of the added resistance due to the impact of weather conditions and due to aggravated propeller working conditions. Moreover, the solution estimation of this problem is very much affected by human factors. Ship master, concerning for safety, can make a judgment that under certain adverse weather loads, it is necessary to slowdown or change ship's course to moderate or bypass the worst condition. In addition, the loading condition of the ship is constantly changing, which governs the basic parameters of the ship: the mass and mass moment of inertia, draft and trim and, consequently, the ship behavior at sea. All these parameters affect the assessment of ship speed, and it is necessary to be conscious of the intensity of their impact on the final value. At the same time, they cannot be predicted with absolute certainty, so the purpose of this analysis is to estimate the impact of weather and operational uncertainties on the actual speed of the ship in real operating conditions.

show abstract