Fortitude (originally Toisa Patroklos), a multipurpose offshore construction vessel (MOCV) of the HX102 design with a main crane capacity of 900t. The DP3 vessel is designed for worldwide operations in the oil and gas sector, ultra-deepwater installation and construction, as well as pipelay and heavy lift support.

Vessel type




Built by

Hyundai Heavy Industries, South Korea



Owned by

Toisa Ltd

Designed by

Ulstein Design & Solutions BV

Ordered by

Toisa Ltd

Operated by


IMO Number


Principal dimensions

150.5 m
32 m
Dead weight:
10,000 tonnes
250 POB
Deck area:
2,900 sqm

Note: Subject to selected variant configuration


AHC offshore crane:
900 t
Crane depth operation:
- 3.500 m
AHC knuckle boom crane:
200 t
Crane depth operation:
- 2.000 m
Main moon pool:
8.4 x 8.4 m
Flex lay tower over main moon pool:
550 t
Carousel spaces below deck:
2x2.500 t

Featured solutions

IMO Number: 9687057

Ship history

Toisa was the first to order a customised Deepwater Enabler (HX102 design) newbuild, at Hyundai Heavy Industries (HHI) in Korea.

The vessel is optimised for the installation of flexibles, umbilicals, manifolds, jumpers and other subsea production system components, Fortitude is fitted with two high-capacity active heave compensated offshore cranes (900 t and 200 t respectively) and moon pools for all-weather ROV operations.

The vessel design has been developed for maximum efficiency and cost effectiveness featuring heavy lift capabilities with active heave compensation, two moon pools, and up to 50t/m2 deck strength in key areas. The design includes a number of key features that give maximum capability and flexibility. These features include an AHC offshore crane rated at 900 tonnes SWL (Safe Working Load) with a depth capability of 3,500 metres, and a 200-tonne SWL knuckleboom crane with a 2,000 metres depth capability.

Furthermore, the vessel can accommodate a 550-tonne flex lay tower over the main 8.4 by 8.4-metre moon pool, and two 2,500-tonne-capacity carousels below deck. There is an enclosed ROV hangar for deployment of two large work class deep-water ROVs, over-the-side launch and recovery systems and tether management systems at depths up to 4,000 m.The moon pool is also arranged to allow the deployment of a deck mounted saturation diving bell.

Full compliance with the SPS Code is a fundamental principle of the design, which includes arrangements to meet Comfort Class COMF-V(3), the highest working environment standard.

The deck area is designed to give optimised clear space for the installation of project equipment such as pipelay spreads, and for the carriage and deployment of heavy offshore equipment.

IMO number: 9687057


The multipurpose offshore construction vessel 'Fortitude', previously 'Toisa Patroklos'.
Fortitude is fitted with two high-capacity AHC offshore cranes (900 t and 200 t respectively) and moon pools for all-weather ROV operations. Photo courtesy Allseas.

Allseas bought the vessel in 2018, and renamed it 'Fortitude'. The vessel will dominantly work as an Offshore Support Vessel for Allseas' flagship the 'Pioneering Spirit', which is fully booked with work. Now working on the first part of the Turkstream pipeline across the Black Sea, the Pioneering Spirit will then be heading to Norway for its first installation project, Johan Castberg Topside, in summer 2018, before returning to complete the second part of Turkstream. With three MacGreogor knuckleboom cranes on deck and the ULSTEIN X-BOW design, the 'Fortitude' is a well selected choice to support the Allseas fleet of sophisticated pipe-lay vessels (source:

2021, July:
AUSTRALIA: Allseas multiservice vessel (MSV) Fortitude has completed its first deepwater installation campaign at Chevron's Gorgon field offshore Western Australia. The vessel was deployed for Gorgon Stage 2 (GS2) in the North West Shelf, which involves offshore installation of 11 vertical subsea production trees, over 46 km of production pipelines, nearly 29 km of control umbilicals and 2,840 tonnes of subsea structures at Gorgon and Jansz-Io fields. Allseas is responsible for work package one for GS2, which covers installation of 24-inch Gorgon and 18-inch Jansz-Io corrosion-resistant alloy production flowlines, 8-inch Gorgon and 6-inch Jansz-Io mono-ethylene glycol pipelines, and 6-inch Gorgon and 6-inch Jansz-Io utility pipelines, in addition to 12 pipeline end terminations. In addition to providing pipelay support to Allseas pipelay vessel Audacia, Fortitude also installed subsea structures including manifolds weighing 500 tonnes in 1,320 m (4,331 ft) water depth.
The MSV has headed to Santos-operated Sinbad field in the North Carnarvon Basin where it will undertake its first platform removal scope. It is understood Fugro has contracted Allseas for Sinbad and Campbell platform removal project.

Please contact us for more information

Ulstein Design & Solutions B.V.

Cornerstone Building (6th floor)
Rotterdam Airportplein 32
3045 AP Rotterdam
The Netherlands

Tel: +31 10 475 00 11