Observed Wave Actions on Norwegian Semi-Submersible and TLP Decks

Abstract

Waves have impacted decks on Norwegian semi-submersibles (semis) and TLPs several times. However, it did not get necessary attention before two accidents in 2015. In 2015, a wave impact caused a fatality and four injured on the semi-submersible drilling rig COSLInnovator. The same year, a wave washed away gratings on Scarabeo 8, causing a man to fall 13.5m to the sea. When examining our records, we found 29 reported incidents related to waves in deck on 17 platforms from 2000–2017. 27 of the wave actions were mainly directed upward and the remaining two were mainly horizontal wave hits. We describe each incident and the circumstances. We discuss common causes related to weather conditions and the physical appearance of the platforms. Further, we summarise design and operational precautions taken by the industry.