8/11/2019 Safety Flash Boom Deployment Accident

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Marine Safety Forum Safety Flash 10/25Issued: 24thAugust 2010

Subject: Daughter Craft Boom Deployment Accident

Incident:An ERRV was en-route to her location to begin her tour of duty. Prior to arrival 3 ABs went to theforedeck to deploy the Starboard Daughter Craft (DC) Boom. Later a crewmember appeared at thebridge informing the Master that one of his colleagues had suffered a Head Injury in an Accident.

Aberdeen Coastguard were informed and the casualty was medivacced to hospital. The IP sufferedserious head injuries but is expected to make a full recovery

Investigation Findings:The DC boom is deployed along a static slide (see diagram). The vessel was originally providedwith a double purchase tackle arrangement, the original intention for this equipment was that itwould be deployed by hand and the small and unrated blocks and shackles originally fitted weremore than adequate for that arrangement. However the tackle arrangement had been adapted overtime so that the Windlass drum could be used. This was obviously capable of subjecting the ropes,blocks and fixing points to much higher loads.

On the day of the accident the boom was being deployed with the windlass drum.

When it was almost fully deployed the fixing point on the inboard end of the boom failed. The shackle attached to the fixing point was pulled into the block attached to the starboard

bulwark.

The shackle then forced the cheek-plates apart and it quickly failed.

Due to the strain the arrangement was under the cheek plates and the sheave wereprojected across the deck.

The IP who was operating the windlass handle was struck on the side of the head by thesheave and cheek-plates.

8/11/2019 Safety Flash Boom Deployment Accident

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Immediate Causes:

Improper use of equipment; the tackle arrangement was adapted from manual towindlass power. This at least accelerated but more likely directly caused the failure of therigging arrangement which was suitable for manual power.

Use of Defective Equipment (Aware); during our investigation more than onecrewmember had expressed concerns that this arrangement was less than ideal. It hadbeen discussed informally but no official action had been taken.

Perception that task was routine; During our investigation we heard this task referred to

as part of the ships routine however in reality it takes place once or twice per voyage. Theperception that the task was routine may have lulled all involved into a false sense of safety.

Inadequate equipment; The original intention for this equipment was that it would bedeployed by hand. The small and unrated blocks and shackles were more than adequatefor that arrangement. Following the change from manual to windlass drum operation thesmall unrated blocks and shackles were inadequate for the increased loads they weresubjected to.

Root/System Causes:

Infrequent Performance of Skill; Related to an immediate cause this task is generallyperformed once or twice per voyage. Whilst the task is simple and should fall within the skill

set of an experienced seaman it should not be treated as routine. Inadequate Identification of worksite / job hazards; there was a risk assessment in

place for this task. This had indentified snap back areas and rigging failures as potentialhazards. Whilst the Injured Party may not have been caught by a parted rope he wasdirectly in the line of fire of the parted rigging

Inadequate Preventative Maintenance (lubrication and servicing); The DC boom isdeployed along a static slide (see photos) visible along the static slide is congealed greaseand dry areas. This may have contributed to the boom becoming more difficult to deploy,ergo the need to re-arrange the tackles to utilise the windlass power. This in turncontributed to the increased loads applied to the fixings and rigging, thereby causing or atleast accelerating their eventual failure. In sharing our immediate findings with the affectedvessels one vessel reported back that they still use the hand powered tackles to deploy

their booms. This would seem to indicate that the original arrangement is adequate ifproperly maintained.

Inadequate evaluation and or documentation of change; The booms becoming moredifficult to operate and the change of arrangement of the tackles were not reported throughany of the official channels available to the vessel crew. Such a report could have beeninvestigated allowing the change to be documented, managed and lessons shared.

Inadequate Development of Planned Safe Procedure (co-ordination with process /equipment design); the previously noted change of procedure was not properlydeveloped. If this had taken place the need to have the tackles and shackles replaced withproperly rated items may have been identified.

Inadequate vertical communication supervisor and person; Horizontal communications

on concerns with the arrangements had taken place. These took the form of informaldiscussions between deck crew members on the same vessel and informal discussionsbetween officers on different vessels. These communications were horizontal and had notgone vertically upward or downward. As a result shore management were not informed ofthe crews concerns via any of the official channels available.