The topsides on a boat, ship, watercraft, or floating production storage and offloading (FPSO) vessel, is that part of the hull between the

waterline The waterline is the line where the hull of a ship meets the surface of the water. Specifically, it is also the name of a special marking, also known as an international load line, Plimsoll line and water line (positioned amidships), that indi ...

and the deck.Rognaas, G., Xu, J., Lindseth, S., & Rosendahl, F. (2001). Mobile offshore base concepts. Concrete hull and steel topsides. ''Marine Structures'', ''14''(1-2), 5-23. It includes the visible parts of the bow, stern, sheer, and, if present,

tumblehome Tumblehome is a term describing a hull which grows narrower above the waterline than its beam. The opposite of tumblehome is flare. A small amount of tumblehome is normal in many naval architecture designs in order to allow any small projecti ...

. On an offshore oil platform, topsides refers to the upper half of the structure, above the sea level, outside the splash zone, on which equipment is installed. This includes the

oil production plant An oil production plant is a facility which processes production fluids from oil wells in order to separate out key components and prepare them for export. Typical oil well production fluids are a mixture of oil, gas and produced water. An oil p ...

, the accommodation block and the

drilling rig A drilling rig is an integrated system that drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill wa ...

. They are often modular in design and so can be changed out if necessary allowing expensive platforms to be more readily updated with newer technology. It contrasts with the jacket structure, which constitutes the lower half of the platform structure (the supporting legs and lattice framework), partly submerged in sea.

References

{{reflist Nautical terminology Oil platforms