After the boom of converted floating, production, storage and offloading systems, based on the old VLCC design, many engineering institutes started thinking about optimum dimension for new units. However, these new FPSOs designs carried out worldwide concerns about good seakeeping behavior when considering general weather conditions, in order to apply their project to different locations around the globe. Analyzing the Brazilian specific conditions, it was verified that, considering waves, current and wind characteristics, the dimension proportions found in the projected units were not the best options, mostly because of the swell waves influence. Thus, in a cooperative project between University of Sao Paulo and PETROBRAS, the best dimensions for a specific case were studied, based on real premises from Campos Basin.

During the study, the roll motion, which usually creates operational limits during hard environmental conditions, was focused. It was possible not only to evaluate the best breath and
draught relations, but also the inclusion of a structured skirt in the ship bilge. The influence of different shapes in the ship’s bow and stern were also evaluated, showing interesting results regarding the forces applied on the vessel.

All the analyses were conducted considering numerical analysis, and the final dimensions were applied to a scaled model, which allowed to verify the real behavior of the projected unit in a test basin.

As a conclusion, it was possible to define an optimized hull for the PETROBRAS premises, giving them a real design to be used in future explorations.