Manukau port — a dream or a vision?

For critics of the proposal to develop port infrastructure in the Manukau Harbour, there are scant reasons to attempt it — and 189 reasons not to. That’s the number of souls who perished from the HMS Orpheus on February 7, 1863 after the steamship struck the notorious sandbar at the harbour entrance and was broken up by the incessant waves in New Zealand’s worst maritime disaster.

A 2019 report by the Governmentcommissioned Upper North Island Supply Chain working group did not consider Manukau seriously at all, dismissing it because of navigation and insurance risks.

In July 2020, a former Manukau Harbour pilot and mariner with 30 years of experience in the area, wrote to the Herald to denounce efforts to establish a port in the harbour.

“The entrance of the harbour lies on an open coast offering no shelter, no anchorage,” wrote Brooke Hibberdine.

“During SW gales, swells can attain a height of 6m, and completely alter the bar configuration with the shifting sand.”

Yet, money for a Manukau Harbour technical engineering study was allocated in this month’s Budget, with funding of $3.7 million to be shared with a feasibility study on a national dry dock at Northland and research to assist the development of the freight and supply chain strategy.

So what keeps the Government returning to the Manukau option like a scratched record?

The answer appears to lie in the Sapere report of 2020 by Gary Blick and David Moore.

The key to the Sapere report is an ability to accommodate freight increases predicted to occur over the next 60 years.

For this reason, the Sapere report listed the similarly challenging environment as the Firth of Thames as the second-best option, and largely dismissed Tauranga and Northport.

“The close proximity of Manukau Harbour to the existing industrial area and distribution centres of South Auckland and to road and rail networks means that freight costs would likely be lower than other options.”

The Sapere findings built on a 2016 Port Future Study, which identified three sites in the Manukau Harbour with potential for “an offshore island port connected by a marine bridge”. Blick and Moore looked particularly at the Puhinui area.

“It is likely that the sites located further offshore would incur a higher construction cost, for example, for longer marine bridges.

However, this would be offset by being closer to the natural channel inside the harbour, compared with Puhinui, which is closer to the east shore, and so requires a large amount of upfront dredging in the inner harbour.”

Blick and Moore also note dredging a channel “through the entrance bar would be necessary”.

“Port planners Black Quay revisited the Manukau Harbour concept, as prepared for the 2016 Port Future Study, and reconfirmed that, in their view, it is feasible in principle as a new port, and potentially offers the best location.”

Most critics of the Manukau option point to the notorious sandbar which despatched the Orpheus.

“There is a perception that weather events and the bar at the Manukau Harbour entrance could make access uncertain,” the Sapere report notes.

Modern vessels likely to use a new port in the Manukau Harbour are significantly more advanced and manoeuvrable than those in the past.

“In Black Quay’s view, shipping access to the harbour is a sound concept, taking into account that modern vessels likely to use a new port in the Manukau Harbour are significantly more advanced and manoeuvrable than those in the past.

“Tugboats could be stationed to escort ships through the entrance as a safety measure if needed, and this is not uncommon at ports worldwide.”

The wreck of the Orpheus was eventually blamed on navigation charts.

The sandbar had grown by 800m since the charts were drawn — inexperienced officers were sailing according to out-of-date information.

It’s an unlikely scenario to recur, but the hazardous environment that took the souls of the Orpheus remains, only more volatile as climate change raises the risks of unpredicted weather events.

However, the Allianz safety and shipping review for 2022 reports freight by sea is safer than ever, with record low losses down 57 per cent over the past decade.

The Sapere report offered the tantalising prospect of an offshore island port that can be expanded over time to handle 10 million containers per year.

To attempt setting up a new port in the Manukau Harbour would be intrepid indeed, and an enterprise that might one day come to be described as visionary.