Underwater Sculpture

Anthozoa: Galvanizing Protects the Single Largest Underwater Sculpture in the World

Following the devastation caused by Cyclone Debbie in 2017 across the Whitsunday region, the Queensland and Federal Governments announced a jointly funded $7 million Tourism Recovery Fund. Part of this funding was granted to Reef Ecologic for the Whitsundays Reef Recovery and Public Art Project.

Commenced in 2018, the Project encompassed coral reef restoration activities, as well as the design, creation and installation of six underwater, inter-tidal interpretive art pieces. Installed at Langford Reef, Anthozoa is one of these six sculptures.

Anthozoa is the single largest underwater sculpture in the world. It is a reimagining of the tiny coral polyp, the life source of the reef. It is a symbol of resilience, regeneration and hope at a time when the future of the reef is greatly threatened—and it is protected by hot dip galvanizing delivered by APG Group.

Anthozoa was designed by sculptor Jessa Lloyd, and Ngaro artist Nicky Bidju Pryor’s artwork is featured in the mouth, where the ripples tell a story of change ahead and cultures working together to save the reef.

The name Anthozoa comes from the Greek words ánthos (flower) and zóa (animals) or ‘Flower Animals’, as they were earliest known by biologists, a reference to the floral appearance of the perennial polyp stage of all coral species.

Innovation in Design

Anthozoa was designed using a 3D scan of a real coral polyp that was upscaled approximately 5,000 times. Sculptor Jessa Lloyd said it made sense to create a piece that would have great strength not only in its aesthetic form, but also in its capacity to deliver as a regenerative structure.

“I think nature is the greatest artist ever; Anthozoa was created by using a 3D scan of an actual coral polyp to determine the dimensions and structure then measured up to its current giant scale,” explained Lloyd. “Anthozoa was created using a specially formulated ph neutral concrete mix, which ensures Anthozoa’s 100m2 surface area will provide the perfect surface for new coral to seed on and within the piece exists a chamber filled with crevices and surfaces designed for a range of marine life to shelter.”

Hot Dip Galvanizing: The Only Choice

Anthozoa’s internal structure (or skeleton) is comprised of more than 1,000 linear meters of steel that was hand-shaped to create the form into which the marine-grade concrete layer was bedded. All this steel was galvanized by APG Group before the exterior of the sculpture was coated with concrete.

According to Steve Pollard (Managing Director, APG Group), “Anthozoa is a combination of different materials. Given that it is submerged underwater in the ocean, and covered in concrete, the substrates used in the metal fabricated structure needed a coating that is proven to hold up in that kind of environment. The go-to coating was galvanizing.”

Seawater is severely corrosive to most protective systems, but galvanizing performs well in submerged seawater due to the dissolved salts present in the water. The dissolved salts react with the zinc to form a protective layer that minimises corrosive action.

Not only does the galvanizing protect the steel from corrosion, it also provides structural integrity for the ph neutral, marine grade concrete. Galvanized reinforcement in concrete is a very common technique used in many applications, including coastal and marine structures.

Galvanized steel also delivers higher levels of adhesion to concrete, when compared to uncoated steel. The higher level of chemical adhesion increases the bond between the galvanized steel and the concrete. This bond is then once again increased due to mechanical interlock between the concrete and the surface of the bars used.

Early Involvement of APG Group

The unique nature of the sculpture design required considerable skill and collaboration before the fabrication and galavanizing of the structural base and internal skeleton could commence.

APG Group was engaged early in the design process, which helped ensure that the design concept was clear from the outset. Sculptor Jessa Lloyd, steel fabricators Strathdickie Engineering, and galvanizers APG Group were in close collaboration throughout the design phase to deliver the best possible outcome.

“There was a lot of backward and forwards in the design stage. Like everything, the more effort you put in up front to get the design and critical logistical elements correct, the better the end result,” said Pollard.

In the end, due to its sheer scale, the sculpture was engineered into six separate parts, that came together to create a form that rises over 6m from its polyp base to tentacle tip.

The Galvanizing Process

The key challenge overcome by APG Group during the galvanizing process was the sheer size of Anthozoa. “The enormous size and scale of the sculpture caused some difficulties. We had to create individual components that were able to be transported, able to be galvanized, and able to be reassembled,” said Pollard.

Even when the sculpture was dismembered, the largest piece a 3.8m diameter cylinder. As Pollard explained, this piece was rolled through the zinc to deliver a seamlessly even coating. “There was one large article in particular—a big cylinder. We had to make up a dipping jig. The jig was fitted in the centre of cylinder, one edge of the cylinder was dipped into the zinc, and then it was spun around on the central axis. The cylinder went around and around until it was it covered evenly with the zinc.”

“This rollover dip was further complicated due to the support base that stuck out. Minor modifications had to be made once the sculpture arrived in Townsville to ensure it would fit in the galvanizing bath. Two of the support base legs had to be cut off the sculpture, galvanized separately, and then welded back onto the base later,” said Pollard.

An Underwater Wonderland

With facilities in Cairns, Townsville and Mackay, APG Group has been in the business of galvanizing for over 55 years. Their projects have ranged from road signs, footbridges, and safety barriers, through to railway footing and overhead equipment. And all their projects have one thing in common: superior quality, long-term corrosion protection delivered with unrivalled customer service.

“APG is a long established, large capacity business. We have the machinery, people, skills and knowledge to make whatever projects come our way a success for our clients. Often, it’s the little things—gained over years of experience—that make the biggest difference,” said Pollard.

“It’s certainly not every day you get to work on the tallest underwater sculpture in the world. I’ve never seen anything like it before, and don’t expect to again. With all its unique elements, technical challenges and its high profile nature, Anthozoa was a career highlight. It was fantastic to be involved.”

In an Australian and Great Barrier Reef first, avid snorkellers and divers can now experience an underwater wonderland, protected by galvanizing. The unique artworks, particularly Anthozoa, not only provide amazing scenery for guests to enjoy, they act as a new base for coral growth and animal shelter.

Project Team

  • Client: Reef Ecologic
  • Artist: Jessa Lloyd and Nicky Bidju Pryor
  • Engineer: Paragon Consulting Engineers
  • Steel Fabricator and Detailer: Strathdickie Engineering
  • Hot Dip Galvanizer: APG Group