Crews worked through the night to contain the fire which broke out about 9pm yesterday.
A team of about 20 firefighters remained at the scene on Tuesday afternoon. Two tug boats with firefighters on board have been rotating to cool the sides of the ship.
Fire and Emergency New Zealand’s assistant area commander Mike Bowden said the blaze was contained by Tuesday afternoon and had not spread further into the ship. However it was still not fully extinguished.
Mr Bowden said crews had to be careful with the amount of water they used on the fire to avoid the boat sinking or losing stability.
Work has started to remove some of the water, he said.
"It has been a lot of work for both our paid and volunteer firefighters and we are doing everything possible to extinguish the blaze and keep everyone safe. But it could take some time."
Mr Bowden said it was too early to determine what caused the blaze.
Fire and Emergency had been working with several other agencies at the scene, including Environment Canterbury.
Earlier today, Fire and Emergency's area manager for South Canterbury, Steven Greenyer, said two more crews were on their way from Christchurch and a further two would come from Dunedin to help relieve those who had worked overnight.
"Both paid and volunteer firefighters have been working incredibly hard to get this fire under control, in some pretty trying conditions. The weather overnight has been appalling, it’s been very wet and cold."
"Police have cordoned off part of the port area as a precaution.
