The document defines sub-segments for offshore vessels and structures used in oil and gas exploration and production. It segments vessels and structures based on their function, such as offshore support vessels, drilling units, floating production units, installation/construction vessels and more. Each sub-segment defines the vessel or structure type and lists a key capacity metric for standardization. There are over 12 main segments and various sub-segments defined.

1. Worldyards Offshore Segment Definitions
for Offshore Vessels and Structures
28 January 2015
Segment Definitions for Offshore Vessels & Structures
28 January 2015
1. Offshore Support Vessels I
Sub-segment Definition
Capacity
Measure
1(1)
Anchor handling
tug supply
vessels
(AHTSV)
Anchor Handling Tug Supply - combined offshore supply vessels
and anchor-handling ships. Some vessels also have salvage
capabilities such and fire fighting equipment
BHP
1(2)
Anchor handling
tug vessels
(AHTV)
Anchor Handling Tug - offshore anchor-handling ships. Some
vessels also have salvage capabilities such and fire fighting
equipment
BHP
1(3)
Platform supply
vessels (PSV)
Platform Supply Vessels - vessels that serve permanently positioned
oil rigs by delivering staff, food, equipment and waste removal.
Clear deck
area
1(4)
Emergency
Response &
Rescue vessels
(ERRV)
Emergency Response and Rescue Vessel (ERRV) is an offshore
support vessel with the primary function of being on permanent
standby at offshore installations for the rescue and evacuation of
offshore facilities. Other specific functions include; 1) provision of
medical aid, providing on scene co-ordination for the installation's
Emergency Response Plan, and 2) participating in the execution of
the installation’s collision avoidance strategy e.g. to monitor the
Safety Zone, and warn approaching vessels and the installation of
the risk of collision. The ERRV also; 3) acts as a reserve radio
station.
No. of persons
rescue
capacity
2. Offshore Support Vessels II
Sub-segment Definition
Capacity
Measure
2(1)
Diving support
vessels
Diving support vessels are vessels with floating bases for
professional diving projects.
No. of men
(diving)
system
2(2)
ROV support
vessels
Remotely Operated Vehicles are unoccupied, highly maneuverable
underwater robots operated by a person aboard a surface vessel.
No. of ROV
2(3)
Subsea
Operations
Vessel
Subsea Operations vessels are specialist ships for the offshore
industry with a built in Saturation Diving System and are capable of
supporting on-board Remote Operated Vehicles (ROV’s)
Clear deck
area
2(4)
Well servicing
vessels
Vessels built for well intervention, servicing and workover of
existing wells.
Deadweight

2. Worldyards Offshore Segment Definitions
for Offshore Vessels and Structures
28 January 2015
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3. Seismic Exploration vessels
Sub-segment Definition
Capacity
Measure
3(1)
Seismic
Exploration
vessels
Seismic survey vessels locate subsea oil & gas bearing geological
information, towing array of acoustic sensors(streamers).
No of
streamers
4. Geophysical Survey vessels
Sub-segment Definition
Capacity
Measure
4(1)
Geophysical
survey vessels
Geological survey vessels perform detailed surveys and assessments
of the seabed and the sub-seabed which are critical to the cost
effective design of marine structures and subsea installations.
Length (loa)
5. Miscellaneous Offshore vessels
Sub-segment Definition
Capacity
Measure
5(1)
Pollution
Control vessels
Pollution control or oil spill recovery vessels are vessels with
specialised equipment or cargo
used in the cleanup and collection of maine oil spills.
DWT
5(2)
Seabed Mining
vessels
Seabed mining vessels are engaged in deep sea mining retrieval
processes on the ocean floor. Ocean mining sites are usually around
large areas of polymetallic nodules or active and extinct
hydrothermal vents at about 1,400 - 3,700m
below the ocean’s surface.
Water depth
6. Drilling Units
Sub-segment Definition
Capacity
Measure
6(1)
Jack-up Drilling
rigs
Mobile bottom-supported offshore drilling structures with columnar
or open-truss legs that support the deck. When positioned over the
drilling site, the bottoms of the legs rest on the seafloor. Once the
legs are firmly positioned on the bottom, the deck and hull height are
adjusted and leveled.
Drilling
depth
6(2)
Semi-
submersible
drilling rigs
Floating offshore drilling units that have pontoons and columns that
when flooded cause the unit to submerge in the water to a
predetermined depth. These units have living quarters, storage space,
on the main deck and dynamically positioned over the site, or
anchored. In shallow water, some semi-submersibles can be
ballasted to rest on the seabed. Semi-submersibles are more stable
Drilling
depth

3. Worldyards Offshore Segment Definitions
for Offshore Vessels and Structures
28 January 2015
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than drill ships and ship-shaped barges and are used extensively to
drill wildcat wells in rough waters such as the North Sea.
6(3) Drill ships
Self-propelled exploration vessels able to combine the features of a
survey vessel and an oil rig. These ships are able to accommodate a
high number of personnel and maintain their positions up to weeks
at a time.
Drilling
depth
7. Floating Production Units
Sub-segment Definition
Capacity
Measure
7(1)
Semi-
submersible
Production
Platforms
This type of platform consists of a rectangular deck supported by
columns of submerged pontoons and is held in a fixed position by a
spread mooring system. The deck contains the oil production
equipment.
Production
rate
7(2)
FPSO
(Monohull)
Floating Production Storage Offloading Unit (FPSO) are installed in
offshore oilfields and process crude oil in their topside equipment.
Floating storage offloading (FSO) units are similar, but have storage
and pumping equipment only.
Production
rate
7(3)
Cylindrical type
FPSO(Sevan)
The cylindrical type FPSO is an alternative to ship shaped
production and storage solutions as well as semi-submersibles, TLPs
and Spar platforms. It is a cylindrical shaped floating platform for
oil storage and production. The unit is also known as a Sevan FPSO
for the Norwegian company that developed the uniquely shaped
design.
Production
rate
7(4) SPAR/DDCV
The spar consists of a vertical cylindrical hull and may have
production and oil storage capabilities. The draught is large and
generally about 150 to 200 metres, which significantly reduces the
vertical heave motion. Pitch and sway motions are resisted by a large
metacentric height. The unit is also known as a Deep Draft Caisson
Vessel.
Production
rate
7(5)
Tension leg
Platform(TLP)
A Tension Leg Platform (TLP) is a floating platform which is
connected to the seabed by vertical tendons or tethers. The tendons
are kept under tension by the buoyancy of the platform and this pre-
tension is designed to keep the tendons under tension under all
circumstances, even in large waves.
Production
rate
8. Floating Storage and Offloading Units
Sub-segment Definition
Capacity
Measure
8(1) FSO
Floating storage and offloading system, often a ship or barge-shaped
floating hull incorporating tanks for storage of produced oil, and a
method of loading the oil into tankers. These installations do not
have any production or processing facilities.
Storage
capacity
(barrels)

4. Worldyards Offshore Segment Definitions
for Offshore Vessels and Structures
28 January 2015
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8(2) FSU
A floating facility intended only for storage of oil. Export may be by
pipeline to an onshore facility rather than offloaded to tankers.
Storage
capacity
(barrels)
9. FDPSO
Sub-segment Definition
Capacity
Measure
9(1) FDPSO
Floating Drilling Production Storage Offloading (FDPSO) combine
floating drilling production storage and offloading (FDPSO)
systems. As with FPSOs and FSOs the ships can be based on
newbuildings or conversions. The vessel’s complexity revolves
around the combination of mooring, drilling, and riser tie-in systems
into the same turret. The units are particularly useful in marginal
fields that have numerous nearby drilling requirements. Some
FDPSO units have detachable drilling units that can be removed
partway through the units lifespan. These are also called as
MPF(Multi Purpose Floaters).
Water depth
10. Cryogenic Offshore Units
Sub-segment Definition
Capacity
Measure
10(1) LNG-FSRU
Liquefied Natural Gas – Floating Storage Regasification Units are
offshore structures permanently anchored and performing storage
and re-gasification processes on board. The FSRU will also receive
LNG from ships. After re-gasification, the natural gas will be
transported to shore via a constructed pipeline system.
cbm
10(2) LNG-FRU
Liquefied Natural Gas – Floating Regasification Units are offshore
structures permanently anchored and performing regassification, but
not storage, on board. The FSU will also receive LNG from LNG
carriers. After regassification, the natural gas will be transported
directly, without storage, to shore via a constructed pipeline system.
cbm
10(3) LNG FPSO
Liquefied Natural Gas – Floating, production, storage and offloading
vessels.
cbm
10(4) LPG FPSO
Liquefied Petroleum Gas – Floating, production, storage and
offloading vessels.
cbm
10(5) LPG FSO
Floating storage and offloading system, often a ship or barge-shaped
floating hull incorporating tanks for storage of LPG.and turret for
offloading. These installations do not have any production or
processing facilities.
cbm

5. Worldyards Offshore Segment Definitions
for Offshore Vessels and Structures
28 January 2015
Page 5 of 6
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11. Accommodation Units & Drilling Tenders
Sub-segment Definition
Capacity
Measure
11(1)
Semi-
submersible
accommodation
units
This is a semi-submersible platform/barge that carry
personnel who work on offshore construction projects.
No. of persons
11(2)
Work
accomodation
barges (WAB)
These are normal hull barges or ship-shape vessels that have a large
accommodation space for accommodating personnel who are
working on offshore construction or repair projects. These barges
may have cranes or may not have cranes.
No. of persons
11(3)
Jackup
accommodation
structures
These are jack-up type structures that have a large accommodation
space for accommodating personnel who are working on offshore
construction projects.
No. of persons
11(4) Drilling Tenders
Drilling tender rig can come in either self-erecting (similar to a
jackup), a mono-hull or a semi-submersible. Self-Erecting Tender
Rigs (SETR's) have been used in South East Asia, West Africa and
the Middle East for 30 years for drilling development wells from
fixed platforms. Inherent in the SETR concept is that equipment
required to support the drilling operation such as power, living
quarters, etc, is located on the tender, while only equipment actually
needed for drilling such as the derrick, topdrive, BOP, etc are
installed on the platform. In the late 1990s, came the emergence of
the deepwater tender drilling rig concept. The past decade has seen
the introduction of barge-type tender or a semisubmersible-type
tender. Operators will choose a semisubmersible-type tender as more
appropriate for deepwater or harsher weather conditions.
Drilling Depth

6. Worldyards Offshore Segment Definitions
for Offshore Vessels and Structures
28 January 2015
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12. Installation/ Construction vessels
Sub-segment Definition
Capacity
Measure
12(1)
Pure
Pipe-laying
vessels
Vessels which lay pipes on the sea-bottom. The various methods of
laying: J-Lay, S-Lay, Reel Lay, Flexi-lay are indicated in
sub-segment specific fields.
Maximum
pipe laying
depth
12(2)
Heavy lift crane
vessels including
SubSea
Construction
vessels (SSCV)
Cranes vessels are ships that are specialised in working heavy
cargoes. The largest cranes in the world operate on offshore crane
vessels. Monohull crane vessels have the advantage of a higher
transit speed, but the maximum lifting capacity is achieved on semi-
submersible crane vessels.
SWL of the
crane
12(3)
Offshore
Construction
Vessels (OCV)
These are vessels of different sizes and capabilities. The work scope
is ranging from diving support, pipe-laying and offshore sub-sea
installation to clean-up operations after devastating disasters such as
hurricanes.
DWT
12(4)
Windfarm
Installation Units
Offshore wind farms is a new technology that harness renewable
wind energy out at sea. Windfarm installation units are
platforms/vessels that transport windmills and install them in
offshore waters.
DWT
12(5) Sheerlegs
Sheerlegs are a device mounted on a barge for lifting heavy weights.
This device consists of two strong sections joined together at the top
to which the lifting mechanism is attached. The lifting mechanism
along with the barge is called Sheerlegs.
SWLof the
crane
12(6) Crane vessels
These are vessels that have cranes on board. They are not
submersible, and they are not accommodation barges.
SWL of the
crane
12(7)
Platform
Installation &
Pipelayer
Vessels which are capable of transporting heavy loads (offshore
platforms/topsides/windmills) to offshore locations for installation.
They are usually fitted with heavy lift cranes (greater than 4000mt
SWL). Very often they are fitted with pipelaying equipment.
DWT
Note :
This document has the sub-segment definitions of offshore vessels and structures only. For the sub-
segment definitions of the marine vessels, please refer to www.worldyards.com
All vessels less than 500 GT are not included in our database. The following vessels and structures are
also excluded: Concrete gravity base structure (GBS), harbour tugs, salvage tugs, pushboats (towboats),
liftboats (self-elevating boats) and canal barges .
This is a product of Worldoffshoreyards Pte Ltd (www.worldyardsoffshore.com). Reprinting or reproduction
without explicit consent of Worldoffshoreyards Pte Ltd is prohibited.