Salvaging a sunken Tug Boat

Location:

The Ebute Meta area major channel.
Lagos Nigeria.

Situation:

The Tug boat was pushing a container barge when one of the containers struck the bridge and fell on top the Tug boat.

The barge separated from the Tug and drifted away until it was captured by the Navy.

The troubled Tug hung around the bridge until it finally sank under the 2nd mainland bridge rail way construction area and drifted into the centre of the major channel.
1 casualty.

This is the most difficult part of the sea, an area notorious for currents that make it hard for scuba diving operations.

Divers have only one opening to dive 18-22 meters deep (according  to the tide) for only 45-60 minutes per day for the salvage work.
Heavy currents with speed up to 60 km/h as the tide rushes into the lagoon and returns back to the ocean. A steady situation that lasts almost all day.

Deploying Airlift bags:

The idea was to lay ropes and send shackles and sling wires, strapping them around some points on the tug boat that is resting on it's bridge under the sea bed.

Then, the airbags will be deployed and connected to the shackles and slings wires
Divers hoped to achieve that in the first week of diving.
But they underestimated the tide.

Everyday, the almost non stop moving tide will cause the ropes to tangle around themselves and stuffs around the tug.

Even after the successful deployment of the airlift bags, the tides will twist the airbags into difficult situations.

This led to repeated works under the sea that lasted more than 15 days.

The airbags became ineffective and one slightly damaged when heavy rains increased the sea level up to 25 meters.

They went back to the drawing board for plan B.

The Barge operations.

Using a barge for salvage operations is a well known method.

It will help Divers spend less work time under the sea.

The sea tide and currents will not really affect their operations as the entire crew will be working on board the barge.
It is going to be safer and comfortable.

After pumping water into the front tanks, to lower the barge's draft, they connected the sling wires to the sunken tug boat below.
Then pumped out water, this helped the tug to rise up a bit and when they pumped water into the rear tanks, the boat was lifted up and the barge drifted safely with the aid and control of a rescue Tug boat that pulled the barge away from the currents to an area near Akpongbon sheet pilling in Lagos Island.

At the end, 1 Diver sustained minor injuries. Another fell from the barge into the rough waters but was quickly pulled out by the other crew. They spent 8 weeks to salvage the sunken tug boat.