Key Biscayne (1983/09/01)

19 km NW Ledge Point

A.B.S. A.1. Non-propelled self elevating drilling unit (jack up barge), three triangular truss legs (108.8m length).
Four 25 ton S.W.L. deck mounted cranes, 18.2m diameter helipad on starboard side, accommodation for 95 persons in a four level accommodation block.
Double bottom, machinery deck with two longtitudinal bulkheads.

The jack-up drilling rig ‘Key Biscayne’ was last seen afloat shortly after
1845 hours W.A.S.T. Friday 1 September 1983 in position 31° 10' S, 115° 11' E,
10 nautical miles off Ledge Point on the coast of Western Australia. Shortly
before that time the tow line to the rig supply vessel ‘Atlas Van Diemen'
parted and the standby vessel ‘Argus Guard’, which had been stationed about
5 cables astern, pulled off to starboard to clear the rig as it was running
down with the weather. ‘Key Biscayne’ was clearly seen when about 2
cables off the port beam of the standby vessel both visually and by radar.

However, by the time ‘Argus Guard’ completed its turn, the rig was no
longer visible and radar contact had been lost.

‘Key Biscayne’ was on voyage under tow by two rig supply vessels ‘Lady

Sonia’ and ‘Atlas Van Diemen’ from a location off Darwin to Fremantle for

stacking in Cockburn Sound pending its future employment.

The loss of the rig was the combination of a series of events during the

final day when tow lines parted and gale force winds, rough seas and heavy

swells buffeted the rig. All 52 persons aboard ‘Key Biscayne’ were

evacuated by helicopter and were taken to nearby Lancelin township without loss or injury.

The tow line to ‘Lady Sonia’ parted at 0644 hours 1 September and for the

next twelve hours ‘Atlas Van Diemen' attempted to hold ‘Key Biscayne’ into

the weather and away from the lee shore. Concern for the safety of the

crew and of the rig was felt soon after the tow line to the supply vessel

‘Lady Sonia’ had parted. Shortly after 0900 hours the rig transmitted a

PAN message seeking assistance. By 0930 hours this message had been

converted into a MAYDAY and helicopter assistance was sought to evacuate

crew. At 1110 hours the first man was lifted from the helipad and by 1230

hours all non-essential personnel had been evacuated by both RAAF and

civilian helicopters. Throughout these operations the rig was wallowing in

the heavy seas and swells, rolling and pitching heavily.

During the day it was noticed that the vessel was settling by the stern

and listing to starboard, as heavy green seas were continually washing over

the main deck. The bow of the rig was seen lifting clear of the seas and

the stern immersed as the vessel pitched up to ten degrees forward and

about twenty five degrees by the stern. At the same time the rig was

rolling up to fifteen degrees each side of the upright.

All efforts to reconnect ‘Lady Sonia’ were unsuccessful. At about 1600

hours it was decided that the remaining crew should evacuate before dark

and return the next day when conditions were expected to moderate. The

drift of the rig toward the shore had been slowed by an anchor and the

weight on the tow line. With all line-throwing rockets spent and conditions

on deck too hazardous to work no useful purpose was seen in remaining on

board. By 1620 hours the remaining crew had been lifted from the rig.

The three support vessels remained in the area during the night. At about

0830 hours Friday 2 September ‘Argus Guard’ recovered a guitar case, life

jackets, paper and a trail of debris indicating the location of the sunken

rig.

The position of the wreck was confirmed by bathymetric survey
carried out on 8 and 9 September 1983.
(Department of Transport 1984)