SWATH Research Vessel: The Building of RV Western Flyer

1996 ◽  
Vol 33 (03) ◽  
pp. 233-240
Author(s):  
Michael E. Dockter ◽  
Kurt Schmidt
Keyword(s):  
Weather Conditions ◽  
Model Tests ◽  
Research Vessel ◽  
Monterey Bay ◽  
Station Keeping ◽  
Bay Area ◽  
Deep Diving ◽  
Mother Ship

The design of the SIVA TH (small waterplane area, twin hull) research vessel Western Flyer is described. Because the Flyer is intended to serve as mother-ship for an advanced deep-diving ROV (remote-operated vehicle) to be deployed in CaliJbrnia's Monterey Bay area, the SWATH configuration presents a safe and stable pla(form [kom which to operate in practically all weather conditions. Launch and retrieval of the ROV./?om the sheltered moonpool, or centerwell, are discussed as well as the elaborate 7'ether Alanagement System. The deck and machinery arrangements" are illustrated, and model tests to predict the SWA TH's station keeping qualities and pitch motions in various sea states are described.

DP Ice Model Test of Arctic Drillship and Polar Research Vessel

2012 ◽  
Author(s):  
Torbjørn Hals ◽  
Nils Albert Jenssen
Keyword(s):  
Numerical Models ◽  
Offshore Structures ◽  
Model Tests ◽  
Full Scale ◽  
The Arctic ◽  
Research Vessel ◽  
Station Keeping ◽  
Ice Drift ◽  
Ice Conditions ◽  
Ice Model

The paper presents the results from a series of ice model tests performed as part of the DYPIC (Dynamic Positioning in Ice Conditions) research program. DYPIC is a research and development project within the EU’s ERA NET MARTEC project. The major purpose of the DYPIC project is development of equipment and methods for DP Ice Model testing which allows the prediction of station keeping capability of different vessel types and offshore structures under various ice conditions. The first DYPIC model tests performed in 2011 was conducted with two significantly different vessel sizes, a 68.0000 m3 volume displacement arctic drillship and an 8.600 m3 polar research vessel. The model scale was 1/30 for the arctic drillship and 1/18.6 for the Polar Research Vessel. The model tests were performed in the ice model basin at HSVA using vessel models equipped with thruster capacity similar to full scale operation according to DP class 2 / 3 operations. The DP control system was also modified from normal open water DP operations in order to cope with the highly varying ice drift loads acting on the vessel. The test program gave data supporting the development of numerical models of ice loads from managed ice, see reference [6]. The main focus in this paper is on the station keeping performance and associated thrust utilization as a function of varying ice drift loads. The results and data collected in the first year of the DYPIC program demonstrates that DP ice model tests will be a valuable tool for evaluation of vessel performance prior to moving on to full scale arctic DP operations.

Energetics of Barotropic and Baroclinic Tides in the Monterey Bay Area

2012 ◽  
Vol 42 (2) ◽  
pp. 272-290 ◽  
Author(s):  
Dujuan Kang ◽  
Oliver Fringer
Keyword(s):  
Energy Flux ◽  
Three Dimensional ◽  
Internal Tide ◽  
Submarine Canyon ◽  
Tidal Energy ◽  
Energy Partitioning ◽  
Navier Stokes ◽  
Monterey Bay ◽  
Topographic Features ◽  
Bay Area

Abstract A detailed energy analysis of the barotropic and baroclinic M2 tides in the Monterey Bay area is performed. The authors first derive a theoretical framework for analyzing internal tide energetics based on the complete form of the barotropic and baroclinic energy equations, which include the full nonlinear and nonhydrostatic energy flux contributions as well as an improved evaluation of the available potential energy. This approach is implemented in the Stanford Unstructured Nonhydrostatic Terrain-Following Adaptive Navier–Stokes Simulator (SUNTANS). Results from three-dimensional, high-resolution SUNTANS simulations are analyzed to estimate the tidal energy partitioning among generation, radiation, and dissipation. A 200 km × 230 km domain including all typical topographic features in this region is used to represent the Monterey Bay area. Of the 152-MW energy lost from the barotropic tide, approximately 133 MW (88%) is converted into baroclinic energy through internal tide generation, and 42% (56 MW) of this baroclinic energy radiates away into the open ocean. The tidal energy partitioning depends greatly on the topographic features. The Davidson Seamount is most efficient at baroclinic energy generation and radiation, whereas the Monterey Submarine Canyon acts as an energy sink. Energy flux contributions from nonlinear and nonhydrostatic effects are also examined. In the Monterey Bay area, the nonlinear and nonhydrostatic contributions are quite small. Moreover, the authors investigate the character of internal tide generation and find that in the Monterey Bay area the generated baroclinic tides are mainly linear and in the form of internal tidal beams. Comparison of the modeled tidal conversion to previous theoretical estimates shows that they are consistent with one another.

scholarly journals Ensemble-Based Storm Surge Forecasting Models

2017 ◽  
Vol 32 (5) ◽  
pp. 1921-1936 ◽  
Author(s):  
Amin Salighehdar ◽  
Ziwen Ye ◽  
Mingzhe Liu ◽  
Ionut Florescu ◽  
Alan F. Blumberg
Keyword(s):  
New York ◽  
Storm Surge ◽  
Weather Conditions ◽  
Difficult Problem ◽  
Forecasting Models ◽  
Bay Area ◽  
Temperature Levels ◽  
The Individual ◽  
Specific Sense ◽  
Stated Purpose

Abstract Accurate prediction of storm surge is a difficult problem. Most forecast systems produce multiple possible forecasts depending on the variability in weather conditions, possible temperature levels, winds, etc. Ensemble modeling techniques have been developed with the stated purpose of obtaining the best forecast (in some specific sense) from the individual forecasts. In this work a statistical methodology of evaluating the performance of multiple ensemble forecasting models is developed. The methodology is applied to predicting storm surge in the New York Harbor area. Data from three hurricane events collected from multiple locations in the New York Bay area are used. The methodology produces three key findings for the particular test data used. First, it is found that even the simplest possible way of creating an ensemble produces results superior to those of any single forecast. Second, for the data used and the events under study the methodology did not interact with any event at any location studied. Third, based on the methodology results for the data studied selecting the best-performing ensemble models for each specific location may be possible.

Local wind forcing of the Monterey Bay area inner shelf

2005 ◽  
Vol 25 (3) ◽  
pp. 397-417 ◽  
Author(s):  
Patrick T. Drake ◽  
Margaret A. McManus ◽  
Curt D. Storlazzi
Keyword(s):  
Wind Forcing ◽  
Monterey Bay ◽  
Local Wind ◽  
Inner Shelf ◽  
Bay Area ◽  
Local Wind Forcing

scholarly journals Reduced-Order Modeling of Stratospheric Winds and Its Application in High-Altitude Balloon Trajectory Simulations

2017 ◽  
Vol 56 (6) ◽  
pp. 1753-1766 ◽  
Author(s):  
Sai Sudha Ramesh ◽  
Kian Meng Lim ◽  
Heow Pueh Lee ◽  
Boo Cheong Khoo
Keyword(s):  
High Altitude ◽  
Weather Conditions ◽  
Temporal Variations ◽  
Weather Data ◽  
Compact Representation ◽  
Station Keeping ◽  
Quasi Biennial Oscillation ◽  
Wind Profiles ◽  
Fourier Model ◽  
Trajectory Simulations

AbstractThe knowledge of weather conditions at the stratosphere is important for the planning and execution of high-altitude balloon flights, which require an accurate modeling of weather data over a period of time. Various methods based on statistical analysis, artificial neural networks, and cluster analysis have been employed to model the temporal variation of weather parameters. In the present study, a proper orthogonal decomposition (POD) method has been used to study the spatial as well as temporal variations of wind data in Singapore. The use of POD facilitates a compact representation of the weather dataset and aids in faster computation of wind profiles for use in balloon trajectory simulation. Further, the results reveal the existence of the quasi-biennial oscillation phenomenon, which is characteristic of equatorial easterly–westerly winds. This phenomenon enables the development of a Fourier prediction model, which can be used in real-time balloon trajectory simulations. The Fourier model is observed to be sensitive to wind velocity fluctuations, especially in the vicinity of alternating wind directions. However, it provides a reasonable projection of balloon trajectory, which can be used in preliminary planning and testing of high-altitude flights. Thus, a prior knowledge of wind profiles based on POD or a Fourier model aids in balloon station keeping. A simple case of altitude-controlled balloon flight is presented, and the results highlight the advantages of the present method in balloon station keeping.

The Behaviour of Tugs in Waves Assisting LNG Carriers During Berthing Along Offshore LNG Terminals

2005 ◽  
Author(s):  
Bas Buchner ◽  
Pieter Dierx ◽  
Olaf Waals
Keyword(s):  
Model Test ◽  
Weather Conditions ◽  
Model Tests ◽  
Design And Development ◽  
Test Study ◽  
Wave Conditions

For future offshore LNG terminals tugs are planned to assist LNG carriers during berthing and offloading operations. A model test study was carried out to better understand the tug behaviour in waves and to make a first step in the quantification of the related weather limits. Scale 1:35 model tests were performed in the two important ‘modes’ of a tug during this type of operation: the ‘push’ mode and the ‘pull’ mode. Realistic weather conditions were used and the tugs were working at the unshielded and shielded sides of the LNG carrier. Based on the results presented in this paper, it can be concluded that the motions of tugs in waves are significant, even in wave conditions that are considered to be mild for the berthing and offloading LNG carriers. The resulting push or pull loads may hamper these tug operations significantly. Special measures are necessary to take this behaviour into account in tug design, LNG carrier design and development of operational procedures and equipment. The paper gives insight in the typical tug behaviour in different weather conditions. One should be careful, however, to generalize the present results: with an optimised tug design and operation the tugs can be used in more severe conditions.

Trajectory Prediction of Moored Vessels With Reduced Station Keeping Capability due to Exceeded Anchor Load Limits

2019 ◽  
Author(s):  
Michał Josten
Keyword(s):  
Degrees Of Freedom ◽  
System Analysis ◽  
Equations Of Motion ◽  
Weather Conditions ◽  
Mooring Line ◽  
Force Model ◽  
Station Keeping ◽  
Design Environment ◽  
Trajectory Prediction ◽  
The Time Domain

Abstract This paper presents the development and application of an in-house manoeuvring method for the prediction of the track of a moored vessel in the case of a temporary or total loss of station keeping capability as a result of exceeded permissible anchor loads. The described method is implemented in the in-house ship design environment E4, which already contains a method for manoeuvring simulations. The equations of motion are solved for three degrees of freedom: surge, sway and yaw. Any effects due to dynamic heel are considered quasi-statically. The method is based on a force model with components for environmental and body forces as well as propeller, rudder and steering forces for dynamic positioning applications. For the purpose of mooring system analysis an additional force component for the mooring line loads is introduced by using load-deflection curves. These curves can be calculated within E4 or imported from other sources. The resulting method allows detailed response calculations in the time-domain and can be used in various applications due to its great computational efficiency. In the presented paper the method is used for the analysis of a marine casualty due to harsh weather conditions.

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