Crews have faced severe constraints and a significant increase in workload due to the coronavirus pandemic
There will not be a three ferry service between Devonport and Torpoint until the end of the month now.
It is so staff can carry out routine planned maintenance works on the PLYM and TAMAR ferries.
They have been working on the LYNHER who was undergoing her five yearly refit, but have faced unexpected technical problems within the constraints imposed by COVID-19.
They hope to be back in full operation by Saturday the 29th of August.
Tamar Crossings say although they have offered employment contracts to a number of candidates, they say resuming a three ferry service before all the new staff are in post will create "significant pressure on staffing levels".
They say the delay will allow them to use LYNHER - whose work is due to be completed by the middle of August - as one of the two ferries in operation while works are carried out on the PLYM and TAMAR in turn.
A spokesperson for Tamar Crossings said:
"We recognise that continuing with a two-ferry service for an additional two weeks may create some delays at peak time.
"However the impact of COVID 19 means that, like many other organisations, we have some significant catching up to do in terms of both staffing and technical issues.
"Although we have seen a recent increase in traffic, it is still currently running at around 80% of the normal August levels.
"With the Government committed to the re-opening of all schools in September and more people expected to return to their workplaces after the summer holidays, we want to ensure that we are in a strong position to manage a further increase in traffic levels.
"Completing all of the outstanding works and giving staff the opportunity to take leave in August, while traffic levels still remain lower than usual, will enable us to resume and maintain a three ferry service in time for the bank holiday weekend."