Curved concrete breakwaters protect NZ coast

Situated in the Hauraki Gulf, Waiheke Island Marina is the newest yachting destination in New Zealand, and has 180 docks that need protection from a large fetch and wake from passing ferries.

The environment at the marina is also considered to be ecologically sensitive, being shallow and home to a colony of Little Penguins.

“The concern was that a traditional rock-pile breakwater would impact currents and the area’s delicate flora and fauna,” said SF Marina, which is based in Gothenburg. “Plus, the marina required a new office and parking lot, but the adjacent land was already developed, That’s why SF Marina’s floating concrete pontoons were the ideal solution.”

The two arc-shaped breakwaters actually mirror the island’s scalloped coastline, comprising 23 individual 20m x 6m floating concrete pontoons.

The pontoons are connected with the company’s coupling system, which absorbs and distributes stress loads, with internal steel piles anchoring the breakwater to the seabed.

An office and 2,100m² car park have been built on top of the floating pontoons, which SF Marina claims are virtually unsinkable, with rainwater channelled from the platforms and filtered before going into the sea.

After all, SF Marina says, building on top of floating platforms is not new – “in Sweden, a two-storey, 33-room hotel uses similar pontoons for its foundation,” it says.

Waiheke Island Marina is 40 minutes from Auckland, the most populous city in the country.