ANCHOR PATTERN

 

Design

In offshore operations, barges are usually moored by anchors to maintain position. These anchors are laid in an "ANCHOR PATTERN" designed to suit the barge. However, in many circumstances, deviations from the standard anchor pattern will occur owing to pipeline and / or other obstructions.

An analysis of the anchoring arrangements expected to be utilized in the operation. Among the items to be addressed are:

  • Design environmental conditions of waves, winds, currents, tides and ranges of water depths.

  • Air and sea temperature

  • Description of analysis methodology

The anchoring system should be designed so that a failure of any single component will not cause progressive failure of the remaining anchoring arrangements.

 

Guidelines

In drawing anchor pattern, the following guidelines are among those that shall be applied:

  • Show the bearing and distance of each cable including the angle of wire.

  • Show the spring buoy locations

  • Know the scope of work of barges, i.e. pipe lay, installation, etc.

  • Determine the minimum wire length in conjunction of water depth.

  • The nature of bottom.

  • The wire catenary.

  • Comply with all the mandatory requirements, i.e. distance between anchor and pipeline where it cross at an angle between 60° and 90° shall not be less than 200 meters.

Anchor Wire Caternary Calculations

Catenary calculation for specified water depths and wire weights / sizes shall provide the following information:

  • Touch down points at specified working tensions.

  • Minimum vertical clearance at critical points on the elevated catenary from the pipelines and other obstructions.

 

 

 

MOORING ANALYSIS

  
 

This analysis is performed on behalf of our client, OffShore Geo-Survey, Petra Perdana, Alam Maritim and Petronas Carigali in order to verify the design of safe mooring system for their vessels, i.e. Crest Support 3, Offshore Discovery, Petra Enterprise, etc.

The main scopes of this mooring analysis are to verify the design of the proposed safe mooring system of the vessels and to ensure adequate clearance of anchors to existing sub-sea pipelines.

  
     
 

ANCHOR PATTERN - REFERENCE LIST

  
 

ALAM MARITIM (M) SDN BHD

  • Anchor pattern for BARGE CREST SUPPORT 1 at BEKOK-C platform - May 2010

  • Anchor pattern for BARGE CREST SUPPORT 3 at BEKOK-A platform - May 2010

  • Anchor pattern for BARGE CREST SUPPORT 1 at TEMANA-T platform - September 2010

  • Anchor pattern for BARGE CREST SUPPORT 1 at RESAK-A platform,  offshore Terengganu - November 2010

  • Anchor pattern for BARGE CREST SUPPORT 1 at BARAM-E platform,  offshore Sarawak - November 2010

  
  DUTA MARINE SDN BHD
  • Anchor pattern for CREST NAUTILUS 1 at SMP-A platform, Semarang Field SBO offshore, Sabah - September 2010
  • Anchor pattern for CREST NAUTILUS 1 at SMJT-C platform, Semarang Field SBO offshore, Sabah - October 2010
  • Anchor pattern for CREST NAUTILUS 1 at SMP-B platform, Semarang Field SBO offshore, Sabah - November 2010
  
  TL OFFSHORE SDN BHD
  • Anchor pattern for CRANE BARGE DB 101 for Integrated Transportation and installation of offshore facilities at TBDR-A, TBCP-A, RDP-A, TBFP-A, Tangga Barat Cluster, Terengganu offshore - October 2010
  
  PBJV GROUP SDN BHD
  • Anchor pattern for WORKBOAT AMARCO LYNX at PM3 Camau gas pipeline project - August 2006
  • Anchor pattern for BARGE PENTA PERKASA at BAP-A - July 2007
  • Anchor pattern for BARGE ARWANA for West Lutong pipeline project - October 2007
  • Anchor pattern for BARGE ARWANA for Kepong Tiong pipeline replacement project -April 2009
 
           
 

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