Improvement of maneuverability in a VLCC by a high lift rudder

Zaky, Mochammad; Sano, Mitsuru; Yasukawa, Hironori

doi:10.1016/j.oceaneng.2018.07.030

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…However, even unstable ships should have a more or less symmetrical response to the same input signal, i.e., the rudder angle. Although in general the oscillation periods of ship heading of Zigzag with smaller rudder angle are longer, the sea trial test data of this benchmark ship has shown a much longer period of Zigzag with rudder angle of 10 • than that of 20 • when comparing it with the results from literature (Aoki et al, 2006;Kijima and Nakiri, 2002;Liu, 2017;Yasukawa and Yoshimura, 2015;Zaky et al, 2018).…”

Section: Uncertainty Analysismentioning

confidence: 60%

Effects of adverse sea conditions on propulsion and manoeuvring performance of low-powered ocean-going cargo ship

et al. 2022

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Section: Uncertainty Analysismentioning

confidence: 60%

Effects of adverse sea conditions on propulsion and manoeuvring performance of low-powered ocean-going cargo ship

et al. 2022

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“…Once a decision is made on an appropriate avoidance maneuver (maintaining existing operations may also be an active decision; see section Discussion), the rapidity by which the new operational state is achieved can vary dramatically among ship types (e.g., bulk carriers vs. tankers vs. passenger vessels) and within similar-type ships based on technical features such as hull shape and maneuvering systems (e.g., Yasukawa et al, 2018;Zaky et al, 2018). Further, variation can occur based upon environmental conditions (e.g., Yasukawa et al, 2012;Rameesha and Krishnankutty, 2019) and/or the existing operational state of the ship (wave height, wind, ship's existing speed, acceleration/deceleration, whether or not the ship is already engaged in a turn, etc.…”

Section: Ship Maneuverability During Active Whale Avoidancementioning

confidence: 99%

Active Whale Avoidance by Large Ships: Components and Constraints of a Complementary Approach to Reducing Ship Strike Risk

et al. 2019

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The recurrence of lethal ship-whale collisions ('ship strikes') has prompted management entities across the globe to seek effective ways for reducing collision risk. Here we describe 'active whale avoidance' defined as a mariner making operational decisions to reduce the chance of a collision with a sighted whale. We generated a conceptual model of active whale avoidance and, as a proof of concept, apply data to the model based on observations of humpback whales surfacing in the proximity of large cruise ships, and simulations run in a full-mission bridge simulator and commonly used pilotage software. Application of the model demonstrated that (1) the opportunities for detecting a surfacing whale are often limited and temporary, (2) the cumulative probability of detecting one of the available 'cues' of whale's presence (and direction of travel) decreases with increased ship-to-whale distances, and (3) following detection time delays occur related to avoidance operations. These delays were attributed to the mariner evaluating competing risks (e.g., risk of whale collision vs. risk to human life, the ship, or other aspects of the marine environment), deciding upon an appropriate avoidance action, and achieving a new operational state by the ship once a maneuver is commanded. We thus identify several options for enhancing whale avoidance including training Lookouts to focus search efforts on a 'Cone of Concern,' defined here as the area forward of the ship where whales are at risk of collision based on the whale and ship's transit/swimming speed and direction of travel. Standardizing protocols for rapid communication of relevant sighting information among bridge team members can also increase avoidance by sharing information on the whale that is of sufficient quality to be actionable. We also found that, for marine pilots in Alaska, a slight change in course tends to be preferable to slowing the ship in response to a single sighted whale, owing, in part, to the substantial distance required to achieve an effective speed reduction in a safe manner. However, planned, temporary speed reductions in known areas of whale aggregations, particularly in navigationally constrained areas, provide a greater range of options for avoidance, highlighting the value of real-time sharing of whale sighting data by mariners. Development and application of these concepts in modules in full mission ship simulators can be of significant value in training inexperienced mariners

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“…They suggested that the big advantage of such a bionic rudder was mainly manifested in the post-stall regime, and the maximum lift coefficient of this bionic rudder was nearly 9.4% higher than that of conventional rudders at Re = 8 × 10 5 . Zaky et al [20] discussed the effect of bionic rudders with a fishtail section on maneuverability. The results indicate that the bionic rudder with a fishtail section increases the effective rudder force by approximately 10%, and improves the maneuverability of the Very Large Crude Oil Carrier with a 30% reduction in Energy Efficiency Design Index compared to a conventional rudder.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Investigation of a Winglet-Propeller Using an LES Model

Zhu

Gao

2019

JMSE

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The generation of tip vortex cavitation (TVC) is a common phenomenon in marine propellers. Therefore, it is important to find a way for the effective suppression of TVC. Based on the enlightenment of bionics, a propeller with winglets was numerically investigated by using a large eddy simulation (LES) model and the commercial software STAR-CCM+. Various variables, such as mesh size, number of prism layers, vapor properties and time step, were analyzed using the benchmark MAU5-80 propeller. The open water characteristics calculated for the benchmark propeller were compared with experimental data. The meshes in the region of the tip vortex wake were refined. The power spectral density (PSD) of the thrust coefficient and axial velocity were investigated. The comparison of TVC between the benchmark propeller and the propeller with winglets was studied with the Q-criterion, helicity and volume fraction of the vapor. The strength of the tip vortex wake is weakened by winglets; therefore, the presence of winglets leads to a reduction in vapor volume, which in turn alleviates TVC.

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Improvement of maneuverability in a VLCC by a high lift rudder

Cited by 6 publications

References 6 publications

Effects of adverse sea conditions on propulsion and manoeuvring performance of low-powered ocean-going cargo ship

Effects of adverse sea conditions on propulsion and manoeuvring performance of low-powered ocean-going cargo ship

Active Whale Avoidance by Large Ships: Components and Constraints of a Complementary Approach to Reducing Ship Strike Risk

A Numerical Investigation of a Winglet-Propeller Using an LES Model

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