Giving a second life to laid-up platform supply vessels

A large number of offshore vessels are still cold stacked or idled. The volatility of oil prices and the on-going economic recession gives little hope for a soon recovery of the offshore oil & gas market. Nevertheless, there is potential for an alternative utilisation of this fleet in other markets.

Conversion of a PX121 design including mezzanine and two ROVs.
Conversion of a PX121 design including mezzanine and two ROVs.


The hulls of offshore vessels have become a part of the skyline of many offshore shipping regions. Over 1,800 offshore vessels (excluding rigs) are out of service, many of them for more than 6 years already. This laid-up fleet represents 30% of the total offshore vessel fleet of more than 6,000 units, thus, not all these vessels will find their way into the market again.


Over 600 units are platform supply vessels (PSV), ranging from 50 and up to 99 m lengths, more than 50 of these have not left the construction yard yet. Fifty-five per cent were delivered after 2005, which are vessels with a long life expectancy remaining. Platform supply vessels (PSV) represent a versatile platform that can be adapted to multiple user-applications and situations.

A former Platform Supply Vessel having been redesigned to a yacht support vessel.
A former Platform Supply Vessel having been redesigned to a yacht support vessel.

Anchor handling tug supply vessels (AHTS) and offshore construction vessels (OCV) also present multiple possibilities for their alternative use in other markets.

Alternative market uses for existing platform supply vessels

Ulstein has, in recent years, explored 30 alternative market uses for existing platform supply vessels by means of conversion, upgrades and retrofit solutions.

  • CONVERSIONS: To renew, redesign, and rebuild ships to new technical and functional requirements;
  • UPGRADES: The update, renewal and/or expansion of onboard systems and equipment to higher standards - function, capacity and capability - to re-brand the vessel;
  • RETROFITS: The addition of new technologies or features to existing systems and equipment;

These 30 applications relate to four different vessel markets: the energy markets, the leisure market, the ocean biomass and other miscellaneous industrial and contingency applications.

    Overview of alternative conversion, upgrades and retrofits of existing platform supply vessels.
    Overview of alternative conversion, upgrades and retrofits of existing platform supply vessels.


    Five potential applications

    We have found five possible applications of the platform supply vessels built which have been based on our ULSTEIN PX121 design, these five are highlighted in the table below.

    Summary of five PSV conversion and upgrades based on the ULSTEIN PX121 designed vessels.
    Summary of five PSV conversion and upgrades based on the ULSTEIN PX121 designed vessels.


    More details about these and other case studies can be arranged:

    • PSV conversion into a hospital ship
    • PSV conversion into a walk to work vessel
    • PSV conversion into a yacht support vessel

    Yard conversions

    Our shipyard in Norway delivers high quality ship repair and conversions. Close collaboration between our naval architects and the projects team secures cost-effectiveness, quick responses and complete conversions. Battery retrofits can enhance the attractiveness of the vessel in the market with a minor investment.

    Over the years, Ulstein has gathered multiple experiences from providing vessel life cycle services and giving a second-hand life to vessels in operation. The platform supply vessels of the ULSTEIN PX121 design, 'Esvagt Leah' and 'Esvagt Heidi', were originally built at Ulstein Verft and returned to the yard in 2021 to be upgraded to more environmentally friendly power solutions, and to a new life as ERRV vessels.

    Upgrades and modernisation

    The refurbishment of the 'Ocean Adventurer' expedition cruise vessel included a general modernisation throughout the vessel, with significant technical upgrades, securing a vessel with increased fuel efficiency and, subsequently, a minimized carbon footprint.

    Green solutions: A Platform Supply Vessel can be upgraded with a battery power package and or shore connection.
    Green solutions: A Platform Supply Vessel can be upgraded with a battery power package and or shore connection.
    Upgrading tonnage to a new life
    Upgrading tonnage to a new life

    Upgrading tonnage to a new life

    A shipowner's decision on upgrading a vessel into an updated, ready-classed version, or converting it to a new segment can lead to increased interest and a firm contract. Our shipbuilding team can perform the job, and secure the shipowner a competitive vessel with a short delivery time.

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