SHETLAND Islands Council is already considering purchasing its new Sullom Voe tug after taking it on lease in March.
A business justification case due to be presented to the council's harbour board on Wednesday recommends that the local authority exercises its option to purchase the Multratug 30.
That would cost in the region of £7.6 million, which would be funded by external borrowing.
The estimated annual revenue repayments of £647,000 is a more cost-effective option than the current bare boat charter, which will set the council back £1.04 million a year.
It comes after the council purchased the sister vessel , which also works at Sullom Voe, after initially leasing it.
The tugs, which are said to have surpassed performance expectation, replaced the Shalder and the Tirrick after they were sold to Greek buyers.
The harbour board will also be asked to consider a proposal to rename both the Multratugs Shalder and Tirrick.
The council has options to buy the Multratug 30 one year, two years and three years after delivery.
The business justification case, however, says that "interest rate forecasts suggest a higher rate of borrowing in the medium term (two to three years), therefore it would be advantageous to borrow at the earliest six-month option".
The port of Sullom Voe currently needs four tugs, and its fleet is completed by the Tystie and Dunter.