Diving operations in November All Photographs and slides courtesy of Norwegian Ministry of Defence
Date 27 December 2018
Following the sinking of KNM "Helge Ingstad" after colliding with tanker Sola TS on 8 November, the last press release from the Norwegian Navy was released on Friday 21 December at 9 am:
KNM "Helge Ingstad" has remained stable and diving operations have been going on over the last 24 hours. The divers are working to place the cables and chains under the hull and prepare for passive drainage during lifting. Further diving operations will continue after the holiday period The site is currently monitored by the Norwegian Coast Guard Vessel ‘Tor’ and any movements of the wreckage are monitored.
There will be no further up dates until 3rd January 2019
The operation is currently between phases 2 and 3 described below
The crane vessels Gulliver has returned to the standby mooring at Hanoytangen alongside the Rambiz, south of the wrecked vessel location.
Step by step plans of the complete salvage operation have been released on the Norwegian Navy website and are copied hereunder.
1 Securing the vessel
There are several uncertainties that can affect the schedule, including weather conditions, the vessel's stability and the risk of contamination. Before the vessel can be raised, it must be secured. The focus throughout the operation is in order of precedence:
Personnel safety, Environmental Issues, Material concerns. There are 26km of oil spill booms around the wreckage. The vessel is held fast by cables.
The vessel's movements are continuously monitored. Maintenance and further securing are assessed on an ongoing basis. The Navy have personnel on shore at Sture and the site location Commander onboard the KNM Olav Tryggvason.
3 Preparation for lifting
Before starting to raise the frigate there are two essential activities that need to be completed.
- Debunkring: Divers are preparing for drilling into the appropriate tanks to drain the fuel oil with hoses (red circle).
- Preparation for the lift: The cables and chains are prepared under the vessel ready for the lift
The whole operation is monitored by an ROV camera
4 Detailed planning
The Detailed planning is carried out at Haakonsvern, the main base of the Royal Norwegian Navy, and takes all risk assessments into consideration
The plan, which is assured and updated based on measures from risk evaluations. Around 40 personnel are involved in the operation. There is a large area to cover , including extensive calculations, which should be completed before the operation can proceed.
5 Passive Drainage during Lifting
Draining Water during the lft prepared by the divers is considered critical which will start when when the vessel is safe in the chain slings. Over 10.000 m3 of water will drain during the lift.
6 Preparation for lift
The frigate is manoeuvred into the upright position.
The frigate is slowly lifted to the surface
8 Placing on the barge
The frigate is raised to its normal draft line before being moved on to the submerged barge.
9 Dry Docking
The ship is secured and is out of the water as the barge is de-ballasted to become a floating drydock.
The "KNM Helge Ingstad" is now ready for transportation to Haakonsvern.
Naval divers had extracted naval strike missiles from wreckage on Sunday 2 December. Missiles were brought out when they were considered to be in the way of the salvage process. The assessment to extract the ammunition before the salvage is based on reducing risk to the salvage work and the need for securing measures in later stages of the operation.
The work of securing everything is time-critical when vessel is out of the water and starts when the frigate is on the barge. Further handling of armaments will take place when the vessel is safely secured at theHaakonsvern naval base.
Source Royal Norwegian Navy