Capsize of the crane barge Titan

Summary

The crane barge Titan, under tow by the former research ship Rapuhia, left Sydney at 1700 on 22 December 1992, bound for Singapore. Titan was unmanned.

The tow progressed slowly northwards off the eastern Australian coastline. Throughout 23,24 and 25 December, the tow experienced strong head winds and sea from the north or north-east, and a strong counter current.

By 2200 on 25 December, the tow was making good a speed over the ground of about 1 knot, into a head wind of about 26 knots. At about 2250, those on Rapuhia felt a pronounced jerk and a seaman reported the towing line had parted. No trace could be seen of Titan's riding lights, nor could the barge be seen silhouetted against the sky. Rapuhia was immediately slowed and turned to relocate the tow. A target was seen on the radar and a subsequent sweep by Rapuhia's searchlight showed the barge, floating bottom up. A general call was put out to shipping and the capsize reported to the Australian Maritime Rescue Coordination Centre, Canberra. The vessel's principal in Singapore was also told. On 27 December, divers and people acting on behalf of the owner boarded Rapuhia to assess the damage. The emergency towing bridle was secured to Rapuhia.

It was found that the crane assembly, including the jib and crane tower had fallen off the central lattice work mast. The central mast was bent towards Titan's bow and the slew ring, upon which the crane rotated, was resting at an angle against the central mast.

The upturned barge was towed to a position off Camden Head, out of the strong south-going current to allow work to be undertaken on the upturned hull.

After assessing the situation over a number of days, it was decided that the barge could not be salvaged. The only alternative was to sink it in a controlled manner.

Work to prepare the barge for sinking was carried out off Camden Head. The barge sank at about 2100 on 29 December.

Conclusions

The reason for the capsize of the crane barge Titan is a matter of conjecture but, in the Inspectors opinion, it is probable that a series of events, each one in themselves insufficient to cause a capsize, combined to change the initial stability characteristic of the barge:

1. Given the evidence available, it is probable that during 24 and 25 December, with the working in the seaway, rivets failed in the after starboard section of the barge, allowing a volume of sea water, probably between 500 and 700 tonnes, to ingress into the starboard after spaces. This reduced the intact stability of the barge;
2. The shipping of seas on deck and the probable immersion of the deck edge had the effect of reducing the barge's reserves of stability;
3. The following factors were present and if they coincided may have contributed to the capsizing moment,
   (a) The plunging of the barge, due to a loss of buoyancy at its towed end,
   (b) The periodic rolling,
   (c) Wind heel effect in wind gusts,
   (d) The effect of the crane block and small movement of the jib contributing to the roll;
4. There is no evidence that the chocks welded to the slewing ring to prevent the crane from moving failed before 2300 on 25 December;
5. There is no evidence that the conduct of those on the Rapuhia or the actions of the towing vessel contributed to the capsize;
6. The stability information computed from the inclining experiment of 19 November was substantially correct;
7. The stability criteria adopted by AMSA were appropriate and allowed reasonable reserves of stability. Notwithstanding the fact that Titan immersed its deck edge at an angle of heel of 9.6 degrees, there was a large reserve of stability at this angle;
8. The AMSA surveyors followed the Authority's Instructions to Surveyors. However, the Titan was not typical of tows normally envisaged in these instructions and it would have been appropriate to consider more fully the engineering aspects of stresses imposed by the crane structure on the securing arrangement and the hull of the barge;
9. The fact that the Rapuhia was unseaworthy by virtue of false certification and the false certificates carried by the Mate and Chief Engineer were not contributory factors to the capsize and loss of the barge.