Biological invasion (bioinvasion) is a major socio-environmental threat that impacts biodiversity, due to the ease of dispersal and competitive advantage, and also impact the surrounding population and activities such as fishing and tourism. The sun coral is one of the marine bioinvasive species in Brazil and its control and monitoring requires constant cleaning of the hulls of ships and semi-submersibles used by oil and gas drilling companies.

While the call for hull cleaning is not new, in the last two years, new rules and standards have been introduced in Brazil for cleaning specifically directed at exotic species. In addition, many hull cleaning technologies are known but not yet applicable to the removal of sun coral from hulls.

As a result, the removal of its biofouling is now one of the main challenges of drilling contractors working in Brazil. The call for the removal of sun coral from hulls is growing every day, and since the cleaning operation is costly and time-consuming, it has received considerable attention and has been the subject of studies to optimize it. Cleaning a hull involves the utilization of diving teams, in a manual and high-risky activity, for the lack of other applicable technology. In this sense, the objective of this paper is to present a bibliographic review on the subject, and to present a case study of the hull cleaning activity of four offshore drilling rigs for the controlled removal of fouling biota by sun coral.

This paper is based on a case study of the controlled removal of sun coral using diving teams, from four (4) drilling units, three (3) semi-submersible and one (1) drillship, performed in 2022 in Guanabara Bay, Rio de Janeiro. The data analyzed were live area worked, duration of the cleaning operation, number of teams, average number of teams per day, and area worked per day.

The acquired data may be useful for planning future maneuvers for the removal of exotic species, as well as the cleaning of biofouling from the living works of offshore drilling units, as it presents comparable data and similar activities.

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