Check Your Rigging Arrangement During Deployment of Clump Weight


What is rigging?

  1. The use of mechanical load shifting equipment and associated gear to move, place or secure a load using plant, equipment or members of a structure to ensure the stability of those members; or
  2. The setting up or dismantling of cranes or hoists.


During rigging operation, a clump weight was attached and deployed to a riser through the moonpool.  The vessel was in the process of installing a riser as part of a large field development in 400m water depth.  In order to prevent damage to the riser during deployment of the clump weight, a hold-back winch was connected to it via a two part bridle and ROV hooks.  The winch would then pull the clump weight forward to allow it to be lowered without clashing with the

Once deployment of the clump weight had come to a stop, tension was released from the hold-back winch and a rigger was instructed to enter the work area and disconnect the two slack ROV hooks by pulling on release ropes.  The deck supervisor then signalled for the winch operator to commence hoisting up on the winch.  It was during the winch hoisting movement that the “extension beak” on one of the ROV hooks got snagged.  The beak parted which resulted in the two part bridle complete with ROV hooks and winch wire flying up and striking the rigger knocking him off his feet to deck.

Operations were suspended and the raiser suffered a closed fractures to the radius and ulna bones of his left

On investigation the following causes were identified:

  • Lack of hazard awareness and consequence for a routine task;
  • Low risk perception to the task because of other associated higher risk tasks in the same area;
  • The need to identify and mitigate all risks associated with a Management of Change (MoC) process;
  • The Management of Change process should recognise where appropriate the introduction of required additional personnel into the task.


Action Taken:

  • Deck review to identify potential snap back zones and all lines of fire zones for all winch operations;
  • Review of where crew are standing whilst doing this particular job;
  • Further crew briefings covering:
    • Toolbox talk training and workshops
    • Line of fire awareness briefing (IMCA);
  • A review of the Management of Change process and Job Risk Analysis for this operation;
  • Assessment of suitability of ROV hooks for deck rigging activities;
  • Assessment of task procedures and risk assessments – are they available, understood and do they reflect the way the job is actually being carried out;
  • Consideration of possible negative or unforeseen effects of changes made to improve how a task is done;
  • Consideration of the required sequence of activities (e.g. who, what, when?) and agreement and confirmation of readiness before starting work;
  • Identification of any operations/tasks which could expose personnel to a “line of fire” risk.

Riggers must be:

  • Trained to understand and recognize the hazards associated with the assigned task.
  • Qualified to do assigned work and comply with proper procedures.
  • Aware of the surface conditions upon which a crane is operating.
    • The surface should be level within 1% grade and firm enough to support the crane and load.
    • Examine where the load will be set. Remove unnecessary blocks, equipment or other materials that can injure workers if struck by the load.
  • Familiar with the various and correct rigging techniques and rigging equipment (e.g., slings, shackles, hooks, hoist, blocks).
  • Able to anticipate problems before they occur.
    • Stop the job when any potentially unsafe conditions are present.
  • Aware of the weight of the load and understand the rated capacities of the crane and any rigging gear.

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Source: IMCA