Removal of Skeg – Nassau (LHA-4)

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In 2009, HEGER was hired by BAE Systems, Norfolk to assist them with developing a method of blocking the U.S. Naval vessel NASSAU (LHA-4) that would allow removal of the aft skeg. After drydocking the LHA-4 on a 50,000 ton capacity dry dock it was noticed that there was considerable damage to the skeg of the vessel. It was determined the skeg had to be removed for repair. The skeg of an LHA is a major area of support and the blocks under the skeg could not be removed unless additional support to the vessel’s fantail was added.

HEGER worked with BAE’s dockmasters and engineers to develop a method for supporting the fantail with steel towers utilizing existing materials in their yard. Heger prepared a ballasting plan for the floating dry dock to transfer the load from the skeg blocks to the tower blocks. Heger prepared drawings and structural calculations for submittal to the U.S. Navy for their review.

The towers were installed, the skeg removed, repaired and replaced and the vessel successfully undocked in 2009 according to plan.

Original Blocking Under Skeg before skeg removal
Figure 1 – Original Blocking Under Skeg
Towers Added to Support Vessel Fantail to facilitate skeg removal
Figure 2 – Towers Added to Support Vessel Fantail
Skeg Blocks Being Removed by Water Blasting
Figure 3 – Skeg Blocks Being Removed by Water Blasting
Docking of Pathfinder Drill Rig
Design of High Block Towers