Board Meeting Animation - Fire Aboard Construction Barge Athena 106
June 14th, 2007
West Cote Blanche Bay, Louisiana
October 12, 2006
The animation is available in Flash format presented at the Board Meeting on June 14th, 2007, in Washington, D.C.
This three dimensional animation shows the operation of the spud winch and its safety features in the accident involving construction barge Athena 106, deck barge IBR 234, and towing vessel Miss Megan on October 12, 2006 near Morgan City, Louisiana. The accident occurred in the West Cote Blanche Bay oil and gas field en route to a pile-driving site in the northwest area of the field. The end of the animation fades out into video footage taken by the Coast Guard on the day of the accident. This animation is for representational purposes only and does not depict weather or visibility conditions at the time of the accident.
This animation demonstrates the operation of the spud winch and its safety features.
The spud equipment consists of the forward and aft spud and the spud winch.
The spud winch is a twin-drum design.
One drum controls the forward spud and the other controls the aft spud.
Each drum has two brake bands, one on the outside, controlled by the foot brake pedal, and the other on the inside, controlled by the hand control friction lever.
Each drum has a foot brake pedal and a hand lever that act as friction brakes to control the speed of the winch drums as they lower or raise the spuds.
Both forward and aft spuds operate in a similar manner.
(Split screen) This demonstration shows the winch operation on the left, and the forward spud on the right.
The spud starts in the fully raised position.
Dropping a spud from its raised position is a matter of engaging the hand friction control lever and releasing the latched foot brake.
The friction of the brake combines with the spud's weight to ease the spud into the lowered position with gravity as the driving force.
Tension must be kept on the cable while the spud lowers to avoid freefall and having the cable recoil and foul on the drum.
To raise the 5-ton spud, the operator turns on the engine and increases the engine speed using the throttle to develop enough power to lift the spud.
Pulling back on the hand friction lever controls the friction between the winch driveshaft and the drum.
The hand lever regulates the speed with which the drum rotates to lift the spud.
Once the spud is fully raised, the operator uses the foot brake by depressing and latching it, then relaxes the hand friction control lever and shuts down the engine.
With the spud is in its raised position, the winch and its associated equipment offer three safety features to prevent the spud from dropping or slipping.
The first feature is to latch the foot brake in place.
The second is to engage a steel pawl that fits into a notched ring on the outside of the drum to keep the drum from turning in the opposite direction if the brake fails.
Finally, a steel securing pin can be inserted directly through the fully raised spud to prevent it from freefalling if the winch or cable fails.
On the day of the accident, only the foot brakes were used to hold the spuds in their raised position during transit.
Neither of the two other safety features, the pawl and the securing pin, was used to assure that the spuds remained locked in place.
The aft spud released without any brake or mechanical systems impeding its fall.
The spud struck and ruptured the buried natural gas pipeline.