Peak Ice Loads on a Lifeboat in Pack Ice Conditions

2014 ◽  
Author(s):  
Allison Kennedy ◽  
António Simões Ré ◽  
Brian Veitch
Keyword(s):  
Pack Ice ◽  
Ice Conditions ◽  
Ice Loads

Ice Model Tests for Semi-Submersible Platforms in Pack Ice Conditions

2019 ◽  
Author(s):  
Liu Luping ◽  
Li Xin ◽  
Wu Xiao ◽  
Wu Bo
Keyword(s):  
Offshore Structures ◽  
The Arctic ◽  
Floating Platform ◽  
Oil Exploitation ◽  
Pack Ice ◽  
Ice Drift ◽  
Load Cells ◽  
Ice Conditions ◽  
Ice Loads ◽  
Similar Density

Abstract As development of the Arctic grows in intensity, semi-submersible platforms are one of promising type of offshore structures used for arctic oil exploitation. Generally a good ice management is equipped by a moored floating platform to reduce ice loads to manageable levels, thus the most common scenario for a polar operating semi-submersible platform is pack ice conditions. The resistance test of a 4-columns structure is performed in a normal towing tank in China using synthetic non-refrigerated material with similar density to model sea ice. Three component load cells on top of each column and a batch of single component load cells embedded in the surface of the columns near the waterline are used to measure indirect and direct ice loads on the structures. The effects of a series of parameters such as column shapes, orientations, column spacing ratios, ice floe shapes, ice drift speeds and ice concentrations are analyzed.

Winter Navigation through the Strait of Belle Isle

1964 ◽  
Vol 17 (4) ◽  
pp. 364-375
Author(s):  
R. E. G. Simmons
Keyword(s):  
The Third ◽  
The Past ◽  
Shortest Route ◽  
Pack Ice ◽  
Normal Period ◽  
Ice Conditions ◽  
Short Season ◽  
Pass Through ◽  
Alternative Routes ◽  
St Lawrence River

The shortest route from the Great Lakes and St. Lawrence River to Europe passes through the Strait of Belle Isle. The alternative routes pass through the Cabot Strait and are between 100 and 400 miles longer according to the European port of destination. The Strait of Belle Isle is, however, normally closed to navigation from the end of December until the middle of July due to the presence of pack ice and icebergs.Air reconnaissance patrols flown over the Labrador, Belle Isle and East Newfoundland areas seem to indicate that, for the past few years at least, ice conditions have not been so severe as to hamper navigation throughout the normal period of closure. Consolidated ice is only present from the third week of January to mid-February and clears in mid-April to mid-May; only icebergs present a problem in May and June. It is hoped t o show that with proper air reconnaisance at the beginning and end of the ice season, navigation through the Strait could be extended to eight or nine months of the year, or even longer, instead of the present short season of only 5½ months.

scholarly journals Investigation of ship resistance characteristics under pack ice conditions

2021 ◽  
Vol 219 ◽  
pp. 108264
Author(s):  
Seong-Yeob Jeong ◽  
Kyungsik Choi ◽  
Hyun-Soo Kim
Keyword(s):  
Ship Resistance ◽  
Pack Ice ◽  
Ice Conditions

New records of mummified crabeater seals on islands bordering Admiralty Sound, Weddell Sea

2019 ◽  
Vol 31 (3) ◽  
pp. 109-115
Author(s):  
Javier Negrete ◽  
Leopoldo H. Soibelzon ◽  
Esteban Soibelzon ◽  
Jorge Lusky
Keyword(s):  
Open Water ◽  
Weddell Sea ◽  
Pack Ice ◽  
Breeding Grounds ◽  
Ice Conditions ◽  
Crabeater Seals ◽  
Ice Floes ◽  
Early Breakup ◽  
Natural Trap ◽  
Seymour Island

AbstractNinety-six mummified crabeater seals discovered at Seymour Island (Isla Marambio) are reported. Each specimen was georeferenced, photographed and assigned to five different taphonomic states. Previous work stated that seals at Seymour Island get stranded inland around the breeding season. However, it is not clear if the species breeds in this area. The abundance of crabeater seals and the ice condition along Admiralty Sound (Estrecho Bouchard) were obtained by aerial surveys during spring (2015–17). It appears that the species uses the strait as a passage to breeding grounds. Under heavy ice conditions, the seals become stranded in the middle section of this strait and wander inland through a valley that represents the mouth of an ephemeral stream that ends at the pack ice level. This situation was observed in 2014 and 2015 when recently dead seals were found, evidencing that this natural trap is still active. Nonetheless, in 2016 and 2017, during an early breakup of Admiralty Sound, the seals that remained in the area were more numerous than in 2015 but they did not get stranded inland. This early breakup may encourage the seals to breed there in the presence of open water areas with ice floes.

Model Tests on a Spar in Level Ice and Ice Ridge Conditions

2009 ◽  
Author(s):  
John Murray ◽  
Stephane LeGuennec ◽  
Don Spencer ◽  
Chang K. Yang ◽  
Wooseuk Yang
Keyword(s):  
Full Scale ◽  
Scale Model ◽  
Test Facility ◽  
Mooring System ◽  
Scaling Effects ◽  
Line System ◽  
Restoring Forces ◽  
Ice Conditions ◽  
Ice Loads ◽  
Level Ice

1:30 and 1:50 model-scale ice tests of an ice-resistant Spar design were carried out to determine the loads on the Spar in level ice and ice ridges. Due to limitations in the depth of the ice test facility, the hull draft and mooring system were truncated. The 1:30 scale model was towed through the ice on a fixed and compliant dynamometer. The stiffness characteristics of the compliant dynamometer matched the horizontal stiffness of the full-scale mooring system. The purpose of these tests was to compare the mooring and ice loads measured in fixed and compliant conditions. The 1:50 scale model was truncated by 70 m. Its mooring system was modeled using a four-line system designed to give the same global restoring forces as the full-scale mooring system. The model was fitted with vertical plates on the exterior of the hull to compensate for loss of added mass and added moment of inertia. A limited number of tests were carried out at the two model scales in the same ice conditions to investigate scaling effects. The mooring and ice loads measured in the fixed and compliant conditions were found to be similar, indicating that loads estimated, assuming the structure is fixed, provide good estimates. Good agreement between the two models was also found for the tests carried out in the same ice conditions, suggesting that the scaling effects may be negligible.

Probabilistic Modeling of Extreme Value Distributions of Ice Loads on “Molikpaq” Platform for Sakhalin-II Project

2013 ◽  
Author(s):  
Alexander T. Bekker ◽  
Olga A. Sabodash ◽  
Roman G. Kovalenko
Keyword(s):  
Numerical Modeling ◽  
Return Period ◽  
Statistical Data ◽  
Extreme Values ◽  
Ice Cover ◽  
Offshore Structures ◽  
Extreme Value Distributions ◽  
Probabilistic Estimation ◽  
Ice Conditions ◽  
Ice Loads

Characteristics of the drifting ice cover and the scenarios of the ice loads on offshore structures are the major parameters defining durability and reliability of the ice-resistant platforms on the Sakhalin offshore. The study is devoted to the problems of probabilistic and numerical modeling of the process of interaction between the ice cover and the ice-resistant concrete structures on the Sakhalin offshore zone. Geometry of the “Molikpaq” (PA-A) platform for Sakhalin-II Project is used as an example. The input statistical data were received on the basis of full-scale observations of the ice conditions in the Piltun-Astokhskoe deposit area during 1989–2002. The distribution of probability exceedance of ice loads for various ice scenarios on the “Molikpaq” (PA-A) platform was received. A probabilistic estimation of extreme values of ice loads was carried out, taking into account return period of ice conditions.

The Design, Installation, and Performance of a Berm-Supported Exploration Structure in the Beaufort Sea

1985 ◽  
Vol 107 (2) ◽  
pp. 188-194
Author(s):  
K. J. Hewitt ◽  
W. E. Berzins ◽  
J. P. Fitzpatrick ◽  
H. G. Hogeboom
Keyword(s):  
Case History ◽  
Beaufort Sea ◽  
Wave Loads ◽  
Extreme Temperatures ◽  
Related Activity ◽  
Design Considerations ◽  
Ice Conditions ◽  
Ice Loads ◽  
And Performance ◽  
Placement Technique

The design, installation, and performance of a berm-supported exploration structure in a dynamic ice environment is presented. Details are provided on design considerations which include horizontal ice loads, wave loads, seismic considerations, foundation characteristics and extreme temperatures. The development of specifications and installation techniques to account for these design concerns is presented. A case history is presented which includes a discussion of on-site modifications to the idealized placement technique, which were necessitated by extreme ice conditions. The success of this modified placement technique is confirmed through a review of the units performance during the drilling season, and the response of the structure to dynamic ice and drilling-related activity is examined.

Model tests of dynamic ice loading on the Chinese JZ-20-2 jacket platform

1992 ◽  
Vol 19 (5) ◽  
pp. 819-832 ◽  
Author(s):  
G. W. Timco ◽  
M. B. Irani ◽  
J. Tseng ◽  
L. K. Liu ◽  
C. B. Zheng
Keyword(s):  
Ice Sheets ◽  
Ice Thickness ◽  
Bohai Bay ◽  
Test Program ◽  
Jacket Platform ◽  
Prototype Structure ◽  
Ice Conditions ◽  
Ice Loads ◽  
Structure Orientation ◽  
Good Agreement

A model test program has been performed to study the dynamic ice loads on a jacket platform used in Bohai Bay, China. The tests were performed at a geometric scale factor of 1:26. The prototype structure/foundation compliance was modelled and the structure was subjected to scaled ice sheets corresponding to the ice conditions in the Bohai Bay. The loads, moments, displacements, and accelerations of the structure were measured. The test variables include the ice thickness, ice speed, elevation of ice cover, and structure orientation with respect to the ice motion. An analysis of the data shows good agreement with measured full-scale information. Key words: ice, loads, dynamic, vibration, jacket structure, foundation, China.

Evacuation in Ice: Ice Loads on a Lifeboat During Field Trials

2013 ◽  
Author(s):  
António J. Simões Ré ◽  
Brian Veitch
Keyword(s):  
Field Measurements ◽  
Emergency Evacuation ◽  
Field Trials ◽  
Hull Form ◽  
Pack Ice ◽  
Scale Field ◽  
Ice Loads ◽  
Ice Field ◽  
Operational Issues ◽  
And Training

Full-scale field trials of a conventional lifeboat in pack ice have yielded insights into the design and operation of evacuation craft in ice. The multi-year trials program used an instrumented lifeboat to investigate design considerations such as powering and propulsion, hull form, maneuvering, ice loads and ergonomics. Operational issues that have been examined include ice management for emergency evacuation, coxswain competence and training. This paper focuses on local ice loads measured on the hull during aggressive operations in pack ice. Field measurements are presented and the implications for design and safe operations are discussed.

Discussion on the preceding papers

1967 ◽  
Vol 252 (777) ◽  
pp. 209-212
Keyword(s):  
Elephant Seal ◽  
Short Term ◽  
Marginal Population ◽  
Secular Changes ◽  
Long Period ◽  
Signy Island ◽  
Pack Ice ◽  
Seal Population ◽  
Ice Conditions ◽  
The Antarctic

J . E. Smith. May I ask, at the outset of our discussion of this morning’s papers, whether there is any evidence of long- or short-term secular changes of climate in the Signy Island area? G. de Q. Robin. J. A. Heap, in preparing an ice atlas of the Antarctic seas, drew upon the long period of meteorological records from the Argentine station ‘Orcadas’ on Laurie Island, South Orkney Island, and from the British station at Grytviken, South Georgia. He was able to show that in the late 1920s there were several years with mean annual temperatures 1 or 2 degC below average, while in the 1950-60 period moderate fluctuations in climate could be associated with fluctuations in the pack ice. M. W. Holdgate. Because of the lack of suitable ‘indicator species’ in the land flora, pollen analysis from the Antarctic zone is not likely to help in this problem. However, some evidence of climatic change may be derived from the fluctuating fortunes of the small elephant seal population at Signy Island. When first studied by R. M. Laws in 1948 this was producing 80 to 100 pups annually: latterly numbers have fallen off dramatically and in some seasons only four or five have been born. This is a marginal population of a species not penetrating deeply within the ice zone, and hence will probably be a good indicator of changing climate and ice conditions.

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