The Defence Force is seeking tenders to replace its only fuel tanker, HMNZS Endeavour.
HMNZS Endeavour, which is due to be decommissioned in three years, can refuel ships and helicopters at sea.
The ship will reach the end of its service life in 2018 and will also no longer comply with international maritime regulations.
The Defence Force is looking to replace it with a similar type of vessel. Tenders close in June.