During the summer season of 2005, there were

2 weekly Tórshavn to Lerwick depatures (Mondays & Fridays)
(Duration: 12 hrs 30 mins)
1 weekly Lerwick to Tórshavn departure (Wednesdays)
(Duration 13 hrs 30 mins)

Source: Visit Shetland 2005 Brochure

Distance: 211 (?)
(The brochure does not stats whether the distance is measured in miles or kilometers at all)