The 1984-built, Cemfjord, managed by Brise Hamburg capsized in heavy weather while sailing from Aalborg, Denmark bound for Runcorn in the UK where it was due to arrive on Monday with a cargo of 2,000 tonnes of cement.
The upturned hull of the cement carrier was spotted by a local ferry at 1430hrs local time on Saturday, which contacted the Shetlands Coastguard.
“No distress call was received from the vessel. Bad weather prevailed in the area at the time and conditions remain difficult at the scene, with storm force winds,” Brise said in a statement.
The vessel had a crew of eight onboard comprising seven Polish seafarers and a Filipino master. The search for the missing crew started again on Sunday and the UK's Maritime and Coastguard Agency (MCA) said: "The two helicopters and four lifeboats have resumed their search and will be joined by coastguard rescue teams from Kirkwall, St Margarets Hope, Duncansby, Scrabster and Wick. HMS Somerset and her helicopter have also joined the search."
The 1984-built general cargo vessel was converted to cement carrier in 1988.