What is a 'bridging document', and why did the TSB recommend its use following the Titan investigation?

A. A document used to clarify how operations and emergency response will be coordinated and how safety will be managed when one or more separate organisations are working aboard the same vessel — common in the oil & gas industry but not required for operations like Polar Prince/OceanGate

B. A structural engineering report bridging the gap between design theory and as-built hull testing

C. A temporary certificate issued to bridge a gap in a vessel's class survey cycle

D. A communications log bridging ship-to-shore reporting during search and rescue

A. A sphere distributes external hydrostatic pressure evenly across its surface, avoiding stress concentrations

B. A sphere is cheaper to manufacture from carbon fibre

C. A cylindrical hull cannot be pressure-tested before sea trials

D. A sphere allows a higher passenger capacity for the same hull weight

A. They were never validated to confirm they matched the theoretical values used in the original design

B. They exceeded design specification and provided an additional safety margin

C. They were validated by an independent classification society prior to first dive

D. They matched design values but degraded only after the fifth dive