Course stability and yaw motion of a ship in steady wind

Yasukawa, Hironori; Hirono, Tetsuro; Nakayama, Yoshiyuki; Koh, Kho King

doi:10.1007/s00773-012-0168-z

Cited by 24 publications

(9 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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. ; Chen et al, 2017).…”

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

View full text Add to dashboard Cite

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

show abstract

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

View full text Add to dashboard Cite

show abstract

“…In these studies, Spyrou et al (2005Spyrou et al ( , 2007 found that limit cycles of oscillation occur at small rudder angles with low wind velocities, but they did not provide any explanations of yaw motion stability at higher wind velocities. Further investigation of yaw behavior under wind action was undertaken by Yasukawa et al (2012), who specifically studied the effects of wind velocity and wind direction on yaw, including the oscillation of yaw motion. These studies used a three-degree-of-freedom (3-DOF) mathematical model of ship maneuverability under the assumption that the ship's forward speed does not significantly change due to wind and that the drift motion is small.…”

Section: Introductionmentioning

confidence: 99%

Yaw Motion Stability of an Indonesian Ro-Ro Ferry in Adverse Weather Conditions

Perdani

Juliansyah

Putri

et al. 2020

IJTech

View full text Add to dashboard Cite

The yaw motion stability and course-keeping ability of ships are important factors with regard to collision danger, particularly for ships operating in narrow channels, crowded routes, or port areas. Yaw motion may become unstable due to external forces, such as wind. To investigate yaw stability and course-keeping ability, this study developed a nonlinear dynamic system of a three-degree-of-freedom mathematical model to determine steady state equilibrium. Yaw motion behavior was then analyzed using the eigenvalue characteristic of the obtained equilibrium points. The numerical results for an Indonesian ro-ro ferry showed that the rudder angle required to maintain the ship's course tended to increase as wind velocity increased. In beam wind, the necessary rudder angle was larger than the maximum possible rudder angle when the wind velocity was 24 m/s or more. The ship could be controlled by the rudder during operation, but its yaw motion tended to be unstable in following wind. The stable oscillation of yaw motion occurs when the wind velocity is higher than 11 m/s, and the range of heading and rudder angles increases as wind velocity increases.

show abstract

“…Then, [4], [5]and [6] developed numerical simulations where the effects of the towline length and tow point locations to the course stability of a towed ship have been addressed. [7], [8] and [9] performed numerical analyses of towed ships' stability in steady winds. Furthermore, experimental…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics analysis on the course stability of a towed ship

Fitriadhy¹,

Aswad²,

Aldin³

et al. 2017

J. MECH. ENG. SCI.

View full text Add to dashboard Cite

Due to the highly complex phenomenon of a ship towing system associated with the presence of a dynamic nonlinear towline tension, a reliable investigation allowing for an accurate prediction of the towed ship's course stability is obviously required. To achieve the objective, a Computational Fluid Dynamic simulation approach is proposed by investigating attainable and precise course stability outcomes, whilst a hydrodynamic description underlying the rationale behind the results is explained. Several towing parameters such as various towline lengths and tow point locations with respect to the centre of gravity of the barge have been taken into account. Here, tug and barge is employed in the simulation as the tow and towed ship, respectively. In addition, a towing velocity is constantly applied on the tug. The results revealed that the course stability of the towed ship increases in the form of more vigorous fishtailing motions as the towline length subsequently increases from 1.0 to 3.0. Meanwhile, the increase of tow point location from 0.5 to 1.0 leads to a significant improvement in the course stability of the towed ship, as indicated by the reduction of the sway and yaw motions by 227% and 328%, respectively. It is concluded that the increase of tow point location is a recommended decision to achieve a better towing course stability for the barge.

show abstract

Course stability and yaw motion of a ship in steady wind

Cited by 24 publications

References 5 publications

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

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

Yaw Motion Stability of an Indonesian Ro-Ro Ferry in Adverse Weather Conditions

Computational fluid dynamics analysis on the course stability of a towed ship

Contact Info

Product

Resources

About