Index, Section  2 Supports,
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General
                                                                                                  Floaters, FPSO's  is a reference to Hulls that Float, usually ship shape, but it is also used for structures that are not ship shape but Float and may not have storage (FPU, Floating Production Unit). These structures cover such designs as cylindrical hulls, semi sub (submerged pontoon), Spars, Barges etc They are usually purpose built, large scale and able to combat extreme weather. Hulls in this group cover large barges, semi subs, cylindrical profile as the Sevan hulls etc. In the ship shape group the Ugland shuttle tankers were developed with a rounded bow and simple cone mooring, the rounded bow (180 deg) has a profile very similar to the Sevan Units (360 Deg), both deal with the sea in a simple manner that is to a satisfactory degree efficient for the purpose... 
VLCC Hulls, Typical
Modules on a Hull
Hull Hog and sag
Tank Structure
The attributes of a Conventional Tankers were displayed in the previous Section 2b. In terms of usage for an FPSO they are often limiting. For this reason Other Floating Designs incorporate deck stiffening to remove these short comings and can take more concentrated load supports, Section 4 elaborates this fact in Module design
These Floating Designs  show various styles that are not conventional ship shaped hulls. Some are Floating with only retention by moorings, others have buoyant sections and a structure with a direct link to sea floor and can be referred to as an SAL Single Anchor Leg. The main feature of a Floater is that the buoyant section is mainly used to support the topsides. A further advantage of  buoyancy is that it also can be used to float the platform from its building site to its on field loaction.
FPU_Semi Sub_Towers_Compliant_SAL
Semi Submersible
Tethered Platform
Cylindrical Floater
1, Semi Sub, Vesslefrikk, Moored
2, TLP Tethered Leg Platform
3, Sevan Topside, Project Logic
4, SPAR, Outlines
These Floating Designs  show various styles.
Semi Subs can be used as FPU,s,  examples like Vesslefrikk do not have swivels but use an adjacent Fixed Platform for well connection.They also have no storage but use offloading to a shuttle tanker which remains on station or oil export via pipe line.

Ultra large Semi Subs may also be fixed position moored thus not requirig a swivel. An example of an Ultra Large semi sub with substatial legs and submerged pontoons are often referred to as Tethered Leg Platforms or TLP's.

SEVAN Platforms are of a Round Design and Moored in a fixed position. As they do not rotate they do not need a Swivel. 

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General
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a general understanding of Modules 
MODULEitus
Floaters is a broad reference to Hulls that Float, FPSO;s
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These are examples of  various floating Designs which do not need swivels and are often referred to as FPU, Floating Production Units.
1, Spar, Notes, Outline Description
2, Spar, As Built without Supports
3, Spar, Loaded (Wheeled, Lifted) onto Transport Vessel
4 Spar, With Vessel Ballasted to allow Float Off at Destination
5, Spar, Rotated at Location, In Shore, Offshore

The final example is the SPAR Type of Platform, some of their features are contained in the series of Images to the side:-
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