Updated | Heroism of tug crews and efforts of many others praised after stricken ship docks at Port Botany

The "heroic efforts" of tug crews have been highlighted following the docking of cargo ship MV Portland Bay at Port Botany three days after its engines failed off Royal National Park.

Port Authority of NSW chief executive, Captain Philip Holliday, praised all agencies involved in the successful multiagency response.

"From the moment Port Authority was appointed incident controller at 10.20am on Monday, 4 July, protecting people and the environment was at the heart of this operation and every decision," Captain Holliday said.

"I would like to acknowledge the heroic efforts of the towage crews who worked day and night to keep all aboard MV Portland Bay safe.

"The professionalism and skill of the mariners involved were on display for the world to see in truly atrocious conditions. Thank you for your tireless efforts over the past three days."

Captain Holliday said, behind the scenes, a multifaceted group of professionals worked tirelessly to make this operation a success.

"Keeping the vessel stable and away from the coastline, then ultimately, bringing the vessel in for further repairs was a complex task in very challenging conditions," he said.

"The Master of the MV Portland Bay's actions contributed to the success of keeping the vessel and his crew safe as part of the difficult operation."

Captain Holliday said he was incredibly proud of staff and called out the performance and commitment of the Incident Management Team.

He also thanked all agencies involved including the Australian Maritime Safety Authority (AMSA), Engage Towage, Svitzer Australia, Westpac Life Saver Rescue Helicopters and Surf Lifesaving NSW, NSW Ports and the port community at Port Botany, Transport for NSW, NSW Police, Marine Area Command, NSW Environment Protection Authority, NSW National Parks and Wildlife Service, Department of Environment and Heritage, State Emergency Operations Centre, the Regional Emergency Management Office and Port Authority of NSW.

Update - Wednesday afternoon

The stricken MV Portland Bay has been towed safely into Port Botany after being anchored off Cronulla since Monday night.

Four tugs and a pilot boat were involved in the operation.

"Safety has been central to this entire operation," said a statement from the Port Authority of NSW

"All other commercial pilotage were suspended until the Portland Bay and her crew were safely berthed."

Update - Tuesday afternoon

Maritime officials plan to keep the stricken MV Portland Bay stable in its present location off Cronulla until the weather allows it to be towed into Port Botany.

A third tug has arrived from Newcastle to help with the rescue operation.

An update from the Port Authority of NSW on uesday afternoon said the multiagency response team it was leading "is preparing for slow and steady progress in challenging conditions as weather continues to hamper the response to move the MV Portland Bay after she lost power south of Sydney".

Port Authority CEO Captain Philip Holliday said the vessel remains at anchor with both anchors down in a position 1.2 nautical miles off Botany Bay near Cronulla Beach.

"The crew is taking every opportunity while in this situation to undertake repairs to their engines," Captain Holliday.

"Two tugs remain on site with the vessel today and I'm pleased that in the currently stable environment all crew have had the opportunity to refresh and get some rest after working in these extremely difficult and hazardous conditions throughout yesterday and overnight.

"The third Emergency Tow Vessel (ETV), Glenrock has also arrived onsite after punching through southerly headwinds and over 10 metre seas during the passage from Newcastle.

"The specialised vessel with additional deep sea response capability, Glenrock, will be key in the next phase when moving the Portland Bay to safety.

"The priority of this operation remains the safety of all involved and protecting the NSW coastline. All agencies involved are being extremely vigilant in planning every step we take to this end.

"The plan today is to keep the vessel stable in the current location with tugs ready and available so we can affect a tow if needed, but otherwise keep her where she is as we await an improved weather window to bring her into Port Botany."

Earlier - Tuesday morning

The MV Portland Bay was sitting off Cronulla on Tuesday morning after attempts to tow the vessel into deeper water last night were aborted when tow lines broke in the extreme weather and ocean conditions.

The Port Authority of NSW said, after the tow lines snapped, the ship was moved to a more sheltered location in Bate Bay with both anchors deployed and secured, and one tug remaining connected and another close by.

An explanation has been sought as to why the vessel was off Cronulla at first light.

The statement said 11 metre swells were experienced last night before the decision to suspend further attempts to tow the ship out to sea.

"The crew of the MV Portland Bay has been unable to make the repairs required on board and the incident team's preference at this time is to bring the ship into Port Botany when the weather abates so repairs can be undertaken in the safety of a berth and port environment.

"Based on current weather forecasts, it is expected that the ship will remain off shore until at least Wednesday.

"An additional tug with heavy duty emergency equipment is travelling from Newcastle and is expected to arrive at Port Botany in the early afternoon today to provide further assistance.

"The ship is maintaining its position and the crew are safe, their safety and the safety of our frontline responders remains the highest priority.

"The ongoing severe weather conditions makes moving the MV Portland Bay extremely hazardous so the vessel is being supported in position until the weather eases."