Definition(s)
Semi-Submersible
A floating offshore drilling vessel which is ballasted at the drilling location and conducts drilling operations in a stable, partly submerged position.
Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards
Semi-Submersible
Floating structure normally consisting of a deck structure with a number of widely spaced, large cross-section, supporting columns connected to submerged pontoons. NOTE Pontoon/column geometry is usually chosen to minimize global motions in a broad range of wave frequencies.
Source: ISO 19901-7:2013, Petroleum and natural gas industries – Specific requirements for offshore structures – Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units. Global Standards