Friday night/Saturday morning we had exceptionally high tides, even in the estuary that is Manukau Harbour. The picture below was taken about 10 days earlier at nearly full tide. (4.42m vs 3.37m at Onehunga)
The sculpture is at the shore end of the Onehunga sea wall, next to the Manukau Cruising Club. There must be a story behind it – but I have not been able to find anything about it.