The Navy dive ship, HMNZS Manawanui, has arrived in Tonga to support divers trying to confirm the discovery of the sunken ferry, the Princess Ashika.
The dive team has been waiting for the Manawanui to provide a stable platform for the deployment of a remote operated vehicle.
Bad weather means it will be at least Monday before that can happen, and the Navy ship has been battling winds of up to 45-knots while making its way to the scene.
Lieutenant Commander Andrew McMillan says it will take time to carry out the operation.
"They always say take the amount of time you think its going to be and double it. I'm anticipating it will be least a day, overnight and part of the following day before we return to Nukualofa. Its a matter of getting the equipment in the water, flying the actual mission, it will add up to time."
Andrew McMillan says the Manawanui will be checked over before work begins.