Under the contract, Ulstein will provide design, engineering and main equipment for the 83.4m-long PSVs.
The vessels are scheduled to be delivered to Singapore-based Otto Offshore in 2016.
The contract, which has an option for four more vessels, also includes integrated control systems, bridge (radio, navigation), switchboard, diesel electric propulsion and frequency converters, and communication systems.
Ulstein Design & Solutions managing director Sigurd Viseth said: “The PX121 vessels boast a performance you would normally expect from a larger PSV.
“Being able to do this at a medium-sized PSV cost, with reduced emissions and fuel consumption, the ship owner gets a favourable combination of two market areas.”
Capable of supporting offshore activities from shore and in deeper waters, the PX121 vessels are equipped with tanks for various contents such as oil, water, and drilling fluids, as wells as four stainless steel tanks for flammable liquids or corrosive chemicals (LFL tanks).
Certified by DNV and carry the clean design notation, the vessels have a cargo deck of 840m² and a load capacity of 4,000t.
The ships can cruise at a maximum speed of approximately 14.5k and can carry 30 people.
The PSVs will feature the X-BOW hull line design for better performance and increased operability, increased crew comfort and safety and reduced fuel consumption.
Image: Illustration of the PX121 vessels. Photo: © 2013 Ulstein Group ASA.