scholarly journals ‘Mammoth Vessels and Coriolis Force’

1971 ◽  
Vol 24 (2) ◽  
pp. 252-253
Author(s):  
G. R. G. Lewison
Keyword(s):  
Northern Hemisphere ◽  
Coriolis Force ◽  
Forward Speed ◽  
Centre Of Pressure ◽  
Drift Angle ◽  
Centre Of Gravity ◽  
Resistive Forces ◽  
Yaw Angle

Mr. Anneveld's paper (24, 50) would have us believe that the effects of coriolis force on a ship may become appreciable as ship size increases. It is true that the drift angle does increase as the ship's size increases, because the coriolis force given by equation (1) increases as (length)3·5 and the resistive forces increase as (length)3 (on the assumption of geometrically similar ships and Froude scaling). However there is a fundamental flaw in his argument because equation (2) only applies to a vessel with zero forward speed. Moreover the effect of coriolis drift will also be to induce a yaw angle on the ship (because the centre of pressure is forward of the centre of gravity, where the coriolis force may be assumed to act) and this will automatically cause the helmsman or autopilot to apply starboard rudder in the northern hemisphere. This will immediately produce a force on the ship in the port direction, i.e. opposing coriolis force.

Drift Angle and its Consequences in Ship Manœuvres

1978 ◽  
Vol 31 (1) ◽  
pp. 126-132
Author(s):  
K. Meurs
Keyword(s):  
Drift Velocity ◽  
Drift Angle ◽  
Centre Of Gravity ◽  
A Current

When manœuvring ships, mariners usually pay a great deal of attention to the rate at which the heading changes but the direction in which the ship actually moves may differ from the direction in which she is heading. This difference may be caused not only by current but also by the ship's drift velocity through the water in a direction perpendicular to the heading. This velocity is hard to recognize but can cause a turning moment on the ship, whether this is desired or not. In difficult manœuvres which cannot always be accomplished by changes of heading only, one can use the effects of this drift velocity. The drift angle, the angle between the heading and the direction in which the centre of gravity moves through the water, must not be confused with the course allowance necessary to make good a track over the ground when there is a current.

Mammoth Vessels and Coriolis Force

1971 ◽  
Vol 24 (1) ◽  
pp. 50-55 ◽  
Author(s):  
J. C. Anneveld
Keyword(s):  
Coriolis Force ◽  
Drift Velocity ◽  
Practical Importance ◽  
High Latitudes ◽  
Drift Angle ◽  
Moving Vehicle ◽  
Large Vessels

In this paper, a version of which appeared in the October 1969 issue of the periodical Schip en Werf, Mr. Anneveld, who is the nautical adviser to a Dutch firm of marine solicitors, investigates the drift velocity and drift angle due to coriolis force on a vessel of a given size. He shows that these effects are not inconsiderable for large vessels operating in middle and high latitudes and may become of practical importance, particularly when berthing or navigating in the proximity of other vessels.Captain A. Vreugdenhil first drew attention in 1955 to the effect of coriolis force on a moving vehicle and on ships in particular. Since then ships have increased greatly in size and as the coriolis force increases with the mass of the vehicle it may be useful to investigate the effect on the mammoth ships of today.

scholarly journals Asymmetrical heat flow distribution on the mid-oceanic ridges of the World Ocean

2019 ◽  
Vol 489 (2) ◽  
pp. 183-189
Author(s):  
M. D. Khutorskoi ◽  
E. A. Teveleva
Keyword(s):  
Statistical Analysis ◽  
Heat Flow ◽  
Northern Hemisphere ◽  
Coriolis Force ◽  
World Ocean ◽  
Flow Distribution ◽  
Mean Values ◽  
Eastern Flank ◽  
Western Flank ◽  
The World

A statistical analysis of heat flow distribution along nine geotravers crossing the mid-oceanic ridges in the Atlantic, Pacific and Indian oceans is carried out. A significant asymmetry of heat flow distribution is established-its mean values differ on opposite sides of the ridges axis. In geotraverses of the southern Earths hemisphere, their western flank has a higher heat flow mean, and in the geotraverses of the northern hemisphere there is the eastern flank. Various tectonic factors that lead to such a distribution are taken into account, but the universal cause of this regularity is suggested to be the effect of the Coriolis force, which, when the planet rotates, redistributes the magmatic material amount in the asthenospheric reservoir.

Experimental and Numerical Investigation of the Wave-Induced Loads on a Deep-V Catamaran in Regular Waves

2013 ◽  
Author(s):  
Musa B. Bashir ◽  
Longbin Tao ◽  
Mehmet Atlar ◽  
Robert S. Dow
Keyword(s):  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Hull Form ◽  
Proper Understanding ◽  
Towing Tank ◽  
Centre Of Gravity ◽  
Numerical Predictions ◽  
New Research ◽  
Wave Induced

This paper presents the results of towing tank tests carried out to predict the wave loads in regular wave conditions on a Deep-V hull form catamaran model. The experiments were carried out at the Newcastle University towing tank using a segmented model of the university’s new research vessel, “The Princess Royal”. The vessel is a twin hull with a Deep-V shape cross-section. The model, divided into two parts at the cross-deck level, was fitted with a 5-axis load cell at the position of the vessel’s centre of gravity in order to measure the motions response and wave loads due to the encountered waves. The longitudinal, side and vertical forces, along with the prying and yaw splitting moments were measured. The results obtained were further compared with those from numerical predictions carried out using a 3D panel method code based on potential flow theory that uses Green’s Function with the forward speed correction in the frequency domain. The results highlight reasonable correlations between the measurements and the predictions as well as the need for a proper understanding of the response of the multihull vessels to the wave-induced loads due to the non-linearity that have been observed in the experimental measurements of wave loads.

Analysis and Design on Course Control for Sail-Assisted Ship

2014 ◽  
Vol 1008-1009 ◽  
pp. 556-561
Author(s):  
Xing Yang ◽  
Xiang Shun Li
Keyword(s):  
Feedback Control ◽  
Control Method ◽  
Response Speed ◽  
Lateral Force ◽  
Drift Angle ◽  
Analysis And Design ◽  
Feedback Control Method ◽  
The Stability ◽  
Yaw Angle ◽  
The Given

Aiming at the problem that sail-assisted ship is easy to yaw because of sail’s lateral force and adjusts its course slowly due to wind, wave and other interferences on the sea, this paper put forward a feedforward feedback control method based on fuzzy system. According to the relationship between lateral force and yaw angle, a feedforward controller was designed to offset the yaw of ship. In order to correct the drift angle of ship automatically, the feedback controller was fulfilled to track the given course. Feedback control loop adopted fuzzy self-adjusting PD controller to make the drift angle be adjusted in time. The simulations indicate that the feedforward feedback control can suppress the disturbance produced by lateral force effectively, enhance the stability of the system and accelerate the response speed.

STEADY STATE EQUILIBRIUM OF SHIPS MANEUVERING UNDER COMBINED ACTION OF WIND AND WAVE

2015 ◽  
Vol 76 (1) ◽  
Author(s):  
Daeng Paroka ◽  
Andi Haris Muhammad ◽  
Syamsul Asri
Keyword(s):  
Steady State ◽  
Design Stage ◽  
Forward Speed ◽  
Wave Direction ◽  
State Equations ◽  
Ship Maneuvering ◽  
Drift Angle ◽  
Safety Reason ◽  
Combined Action ◽  
Rudder Angle

Maneuverability is important in ship design stage not only for ship performance but also for safety reason regarding the collision and stability especially in quartering following waves. The International Maritime Organization (IMO) therefore developed maneuvering criteria and collision regulation to ensure the ship safety against collision. This paper discusses maneuvering performance of ship under combined action of wind and wave. The steady state equations of ship maneuvering were numerically solved using the Newton-Rhapson method in order to obtain the drift angle, the rudder angle and the ship forward speed. Results of numerical simulations show that the combined action of wind and wave has significant effect on the drift angle and the rudder angle in the range of wind and wave direction between 20.0 degrees and 120.0 degrees. The ship forward speed significantly changes due to alteration of wind velocity in the wind and wave direction smaller than 40.0 degrees or in the wind and wave direction larger than 140.0 degrees. The wave height has significant effect on the ship forward speed in the wind and wave direction between 20.0 degrees and 80.0 degrees.

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