SunStone Ships, Inc, the Florida based passenger vessel tonnage provider, and China Merchants Industry Holdings Co. Ltd. (CMIH) have signed a framework agreement for the construction of four expedition cruise vessels, with an option for further six, SunStone said in a statement.

Ulstein Design & Solutions, which is part of the Norwegian shipbuilding group Ulstein, will provide design and equipment package to the ships as a client of CMIH. Makinen, the Finnish contractor in the cabin and public space sphere, will establish a cabin assembly plant and interior workshop at the shipyard. It will also be responsible for all interior spaces on the vessels.

The ships will have between 85 and 90 passenger cabins and they will be 104 metres in length and have a beam of 18.2 metres, while their draft will be 5.1 metres. The vessels will feature X-bow, a design that Ulstein has patented and which offers superior seakeeping qualities compared to traditional bow designs.

They will have a speed of 15 knots and Finnish/Swedish ice class 1 A, corresponding Polar Code ice class PC6. They will be built to Bureau Veritas class and fly the Bahamian flag, SunStone said.