Whether ports handled overseas or coastal shipping, all came under pressure at some time to keep up with the ever-increasing size of ships. Channels were dug to accommodate them. With deeper shipping channels came the need for larger, stronger wharves and bigger wharf sheds, usually served by the Railway Department, which often oversaw cargo handling on the wharves.
Most ports required dredging, for either development or maintenance work. Bucket and later suction dredges became a common sight from the 1870s. Tugs were also common. Private operators ran the Wellington tugs until the 1970s, but from the 1870s most other major harbour boards had tugs of their own. Ship’s deck machinery did most of the lifting at the smaller ports, sometimes supplemented by a steam crane or two, but from late Victorian times, the major ports added hydraulic or electric wharf cranes, capable of lifting up to 5 tonnes at a time.
Change was a constant feature of the 20th-century waterfront, but until the 1960s it tended to be incremental rather than revolutionary.
Generally, waterfront work was (and is) dirty and dangerous. Furthermore, many New Zealand ports were slow to introduce labour-saving equipment. It is no coincidence that the major industrial disputes in New Zealand history, in 1890, 1913 and 1951, were fought most fiercely on the waterfront. After industrial protests in 1951, the government created a centralised labour bureau, the Waterfront Industry Commission, to employ wharfies.
In 1940 the wartime need for efficiency led to the centralisation of overseas shipping at the main ports. Big ships returned to all the ports except for Ōamaru, Whanganui, Tokomaru Bay and Tolaga Bay; even the small wharf at Ōpua in the Bay of Islands reopened in 1957.
However, coastal ports continued to close under pressure from rail and road. The post-war economic boom sustained the majority until the 1960s. A decline in coal (an important commodity for many ports), the move of oil and cement to large specialist bulk carriers, but above all competition from the new rail ferries, started to take their toll. Kaiapoi was briefly a rare exception, reopening to very small ships in 1958 to bypass Lyttelton’s congested wharves, but closing again in 1967.