Both of today’s NorthLink sailings will now depart at 11am this morning (Tuesday).
Poor weather and tidals conditions have led to the services being brought forward by eight hours.
The sailing from Lerwick to Aberdeen had been due to leave this evening at 7pm. The Hjaltland, meanwhile, had been due to depart in the opposite direction at the same time.
Passengers on the southbound sailing will arrive in Aberdeen early on Wednesday morning.
Northbound passengers will arrive in Lerwick at 10pm tonight.