Bastion was contracted to extensively check the re-design of the navigation mast on our clients deep sea drill ship. Our clients’ project team decided on the following changes to the navigation mast due to ship modifications.

• Lower the platform down to the same elevation as the existing as-built navigation mast.
• Move the box columns inward and support them along the thruster well bulkheads instead of the outward longitudinal bulkheads.
• Increase the platforms depth by 400 mm on top of the mast for communications equipment.
• To facilitate the limited space inside the pilot house and the walkway by the thruster bulkhead, only half of the box column on each side of the navigation deck is used to support the navigation mast.

As a result Bastion ran full finite element analysis on the structure and corresponding communications hardware. All analysis and reports generated were in accordance with American Bureau of Shipping (ABS) rules and guidelines (ABS Rules for Building and Classing Mobile Offshore Drilling (Ref 4.2), in addition to American Institute of Steel Construction (AISC), Manual of Steel Construction, Allowable Stress Design (Ref 4.1).