The 2013 timetable will also see cuts to the Pentland Firth timetable in the off-peak period.
Serco said the changes had been made as a result of “detailed analysis of demand” and alterations had been made to the original proposals following public feedback.
Off-peak sailings from Scrabster to Stromness will be reduced from three sailings each day to two. A special weekend timetable has been introduced with the first sailing at 9am rather than the originally proposed 6.30am. The Hamnavoe bed and breakfast offer has also been extended, however, as previously this was only available during peak season.
Managing director Stuart Garrett said Serco had also altered the dates for low, mid and peak season to fit better with local and national holidays.
He said: “We understand the importance of ferry services to the communities of Orkney and Shetland and will continue to engage with our customers to ensure that we deliver an excellent service to passengers.
“We’ve spoken to the local communities and carefully monitored the demand for services across the year and we believe the new off peak service will fully meet demand for sailings.
“The NorthLink routes will now be more efficient, allowing us to invest in improvements while delivering a service that’s affordable to the Scottish government.”
Full details of the changes can be found on the Serco NorthLink Ferries website at www.northlinkferries.co.uk.