SHIP MOTIONS DURING REPLENISHMENT AT SEA OPERATIONS IN HEAD SEAS

During replenishment at sea operations the interaction between the two vessels travelling side by side can cause significant motions in the smaller vessel and affect the relative separation between their replenishment points. A study into these motions has been conducted including theoretical predictions and model experiments. The model tests investigated the influence of supply ship displacement and longitudinal separation on the ships’ motions. The data obtained from the experimental study has been used to validate a theoretical ship motion prediction method based on a 3-D zero-speed Green function with a forward speed correction in the frequency domain. The results were also used to estimate the expected extreme roll angle of the receiving vessel, and the relative motion between the vessels, during replenishment at sea operations in a typical irregular seaway. A significant increase in the frigate’s roll response was found to occur with an increase of the supply ship displacement, whilst a reduction in motion for the receiving vessel resulted from an increase in longitudinal separation between the vessels. It is proposed that to determine the optimal vessel separation it is vital that the motions of the vessels are not considered in isolation and all motions need to be considered for both vessels simultaneously.

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AN EXPERIMENTAL STUDY OF SHIP MOTIONS DURING REPLENISHMENT AT SEA OPERATIONS BETWEEN A SUPPLY VESSEL AND A LANDING HELICOPTER DOCK

The International Journal of Maritime Engineering ◽

10.5750/ijme.v160ia2.1050 ◽

2021 ◽

Vol 160 (A2) ◽

Author(s):

J Mathew ◽

D Sgarioto ◽

J Duffy ◽

G Macfarlane ◽

S Denehy ◽

...

Keyword(s):

Experimental Study ◽

Water Depth ◽

Research Program ◽

Hydrodynamic Interactions ◽

Scale Model ◽

Ship Motions ◽

Intermediate Water ◽

Large Ship ◽

Future Work ◽

Replenishment At Sea

Hydrodynamic interactions during Replenishment at Sea (RAS) operations can lead to large ship motions and make it difficult for vessels to maintain station during the operation. A research program has been established which aims to validate numerical seakeeping tools to enable the development of enhanced operator guidance for RAS. This paper presents analysis of the first phase of scale model experiments and focuses on the influence that both the lateral and longitudinal separations between two vessels have on the interactions during RAS. The experiments are conducted in regular head seas on a Landing Helicopter Dock (LHD) and a Supply Vessel (SV) in intermediate water depth. The SV is shorter than the LHD by approximately 17%, but due to its larger block coefficient, it displaces almost 16% more than the LHD. Generally, the motions of the SV were larger than the LHD. It was found that hydrodynamic interactions can lead to large SV roll motions in head seas. Directions for future work are provided.

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A Study of Dynamic Responses and Wave Loads on Ships by 3-D Green Function Method

Volume 1: Offshore Technology; Offshore Wind Energy; Ocean Research Technology; LNG Specialty Symposium ◽

10.1115/omae2006-92067 ◽

2006 ◽

Cited By ~ 1

Author(s):

Yoshiyuki Inoue ◽

Md. Kamruzzaman

Keyword(s):

Green Function ◽

Design Procedure ◽

Ship Design ◽

Dynamic Responses ◽

Ship Motions ◽

Wave Loads ◽

Forward Speed ◽

Regular Waves ◽

Field Problem ◽

Dynamic Wave

The dynamic wave loads are the most significant factor for the hull design of a ship. But experimental works for the motion responses of a ship and sea loads on her are expensive and time consuming for individual ship design. Therefore, the development of theoretical and numerical methods for predicting ship motions and dynamic loads on a ship in waves is very important for rational ship design procedure. In general, though 3-D Green function techniques with forward speed need long computation time, however it should be more accurate assumption of the flow field problem on an advancing ship in waves. Nowadays the availability of much faster computer makes the 3-D Green function techniques with forward speed more familiar than before. In this paper, numerical analyses on ship motions and wave loads are presented for ships with forward speed advancing in regular waves. 3-D Green function techniques have been used to carry out the numerical computations for the radiation problem and wave loads for a moving ship. Based on the 3–D linearized potential theory, dynamic wave loads have been computed of a bulk carrier in regular waves where experimental measurements are available. The computations are carried out for various heading angles between head sea and following sea and various ranges of frequencies. The results for motions, and vertical and horizontal bending moments are presented in this paper. Computed results are compared with the experimental data. The results calculated by the present method are found in fairly good agreement with the experimental results and those calculated by the other researchers. Using developed computer code, some parametric studies are also carried out for the ship design criteria and the discussions are made.

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Motion Prediction of the Ship With Sloshing Tanks

Volume 4: Ocean Engineering; Ocean Renewable Energy; Ocean Space Utilization, Parts A and B ◽

10.1115/omae2009-80118 ◽

2009 ◽

Author(s):

Kang Zou ◽

Quan-ming Miao ◽

Ren-qing Zhu

Keyword(s):

Time Domain ◽

Three Dimensional ◽

Panel Method ◽

Ship Motion ◽

Motion Prediction ◽

Ship Motions ◽

Motion Responses ◽

Motion Problem ◽

Good Agreement

Sloshing flow in ship tanks is excited by ship motions, but it affects the ship motions in reverse. This paper focuses on the motion responses of the ship in waves with consideration of coupled effects with sloshing in tanks. A three-dimensional panel method in time-domain is applied to solve the ship motion problem, and the sloshing tanks are solved by commercial CFD software simultaneously. Experiments were carried out on a SL175 ship and good agreement is obtained.

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Prediction of Ship Unsteady Maneuvering in Calm Water by a Fully Nonlinear Ship Motion Model

Modelling and Simulation in Engineering ◽

10.1155/2012/468029 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11

Author(s):

Ray-Qing Lin ◽

Tim Smith ◽

Michael Hughes

Keyword(s):

Experimental Data ◽

Numerical Simulations ◽

Degrees Of Freedom ◽

Ship Motion ◽

Ship Motions ◽

Motion Model ◽

Forward Speed ◽

Fully Nonlinear ◽

Six Degrees Of Freedom ◽

Calm Water

This is the continuation of our research on development of a fully nonlinear, dynamically consistent, numerical ship motion model (DiSSEL). In this study we will report our results in predicting ship motions in unsteady maneuvering in calm water. During the unsteady maneuvering, both the rudder angle, and ship forward speed vary with time. Therefore, not only surge, sway, and yaw motions occur, but roll, pitch and heave motions will also occur even in calm water as heel, trim, and sinkage, respectively. When the rudder angles and ship forward speed vary rapidly with time, the six degrees-of-freedom ship motions and their interactions become strong. To accurately predict the six degrees-of-freedom ship motions in unsteady maneuvering, a universal method for arbitrary ship hull requires physics-based fully-nonlinear models for ship motion and for rudder forces and moments. The numerical simulations will be benchmarked by experimental data of the Pre-Contract DDG51 design and an Experimental Hull Form. The benchmarking shows a good agreement between numerical simulations by the enhancement DiSSEL and experimental data. No empirical parameterization is used, except for the influence of the propeller slipstream on the rudder, which is included using a flow acceleration factor.

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Nonlinear ship motion with forward speed in waves based on 3D time domain hybrid Green function method

Engineering Analysis with Boundary Elements ◽

10.1016/j.enganabound.2020.11.006 ◽

2021 ◽

Vol 123 ◽

pp. 107-121

Author(s):

K. Tang ◽

J.X. Wang ◽

X. Chen ◽

D.P. Jiang ◽

Y.L. Li

Keyword(s):

Green Function ◽

Time Domain ◽

Function Method ◽

Ship Motion ◽

Forward Speed ◽

Green Function Method ◽

Nonlinear Ship Motion

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Prediction Error Statistics in Deterministic Linear Ship Motion Forecasting

Volume 7A: Ocean Engineering ◽

10.1115/omae2018-77456 ◽

2018 ◽

Author(s):

Fabio Fucile ◽

Gabriele Bulian ◽

Claudio Lugni

Keyword(s):

Prediction Error ◽

Theoretical Background ◽

Ship Motion ◽

Irregular Waves ◽

Motion Prediction ◽

Ship Motions ◽

Error Statistics ◽

Numerical Application ◽

Analytical Methodology ◽

Wave Radar

Deterministic ship motions predictions methodologies represent a promising emerging approach, which could be embedded in decision support systems for certain types of operation. The typically envisioned prediction chain starts from the remote sensing of the wave elevation through wave radar technology. An estimated wave field is then fitted to the data, it is propagated in space and time, and it is finally fed to a ship motion prediction model. Prediction time horizons, typically, are practically limited to the order of minutes. Deterministic predictions are, however, inevitably associated with prediction uncertainty which is seldom quantified. This paper, therefore, presents a semi-analytical methodology for the estimation of ship motion prediction error statistics in ensemble domain as function of the forecasting time, assuming linear Gaussian irregular waves and stationary linear ship motions. This information can be used, for instance, to supplement deterministic forecasting with corresponding confidence intervals. The paper describes the theoretical background of the developed methodology and reports some numerical application examples.

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Topics in Development of Naval Architecture Software Applications

10.5957/smc-2013-t14 ◽

2013 ◽

Author(s):

Kevin McTaggart ◽

David Heath ◽

James Nickerson ◽

Shawn Oakey ◽

James Van Spengen

Keyword(s):

Human Resources ◽

Programming Languages ◽

Ship Motion ◽

Motion Prediction ◽

Naval Architecture ◽

Software Applications ◽

Software Documentation ◽

Wave Radar ◽

Directional Wave ◽

Replenishment At Sea

Software applications are used extensively in the practice of contemporary naval architecture. This paper describes several naval architecture applications, including ship motion prediction, simulation of replenishment at sea, simulation of launch and recovery, ship operator guidance, and measurement of directional wave spectra using wave radar. Within this context, this paper describes relevant technologies and programming languages that are effective for development of naval architecture software applications. Due to the complexity of naval architecture software, discussion is given on matching of human resources to software development tasks. Software documentation, which can take several forms, is addressed. Verification and validation of software is the final major topic.

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