Dragline – Opening up Northern New Zealand

Draglines and their skilled operators opened up Northern NZ but hydraulics have largely replaced them; despite the lesser reach of a hydraulic machine.

In Northland, New Zealand, draglines were critical to opening up much of the swamp-ridden region, thereby enabling its conversion to farm land.

Draglines Provide Swamp Excavation

Sixty years ago draglines became widely used for excavation which had previously been limited to spades and shovels and the manpower required to use them. Swamp land was being reclaimed, but at a slow pace. Until these machines began to work the swampy areas, it had only been possible to access the fringes.

Operating a Dragline

Learning to operate a dragline often involved mishap and much frustration and not everyone developed the knack.

New drivers in major civil construction companies were required to accompany and watch a competent driver for up to three months before they were allowed to try the controls. The most critical skill in operating a dragline was a capacity to co-ordinate hands and feet. If tension was lost on the ropes, they would fail to run out smoothly and instead become entangled.

The driver would swing the boom to provide momentum for the bucket which flew out to the desired position and was dropped. Dropping the bucket was managed through pin point control of the foot pedals while it free-fell. As soon as it had dropped, it was immediately winched back in, causing the bucket to load in the process.

Draglines Reclaim Marine Flats in Northland

According to Malcolm Smith, a dragline operator for 45 years, these machines were used extensively in Northland during the early 60s. They were used to reclaim marine flats, provide stop-bank drainage, and for the installation of flood-gates. During the 60s the government subsidised farmers to reclaim marine land which formed part of their property. Many farmers took advantage since they were obliged to pay rates on the otherwise non-productive tidal flats.

When high tide started to come up, the dragline operators would construct a hillock of mud and mangrove, and top it with 16’x4′ pads before positioning the dragline on top to sit and wait until the sea subsided again.

These machines were able to work in raupo (bulrush) swamps. By laying pads from which to operate the machine they were capable of working in areas inaccessible by foot.

Dragline Hazards – Boom Operation Dangerous

High wind and power lines could make dragline operation dangerous. With a 40ft boom it was easy to be careless enough to catch a power line, and if the boom was not locked in position, it was possible for it to be blown around by the wind.

From Roped to Hydraulic Booms

Draglines superseded spades and shovels, but in the early 70s hydraulically operated excavators became available. In New Zealand, many draglines were converted to scrap.

Dragline operators made the natural transition to hydraulically operated booms, especially since many of them came with air-conditioning and radios, but the old timers say they are nowhere near as good as a dragline when a long reach is required.

Dragline Advantage over Hydraulic Booms

A good dragline operator can throw a bucket just over double the length of his boom. With the machine sited on higher ground, they have an even longer reach, providing they have sufficient rope. A twelve ton dragline is capable of pulling six tons, and oftentimes breaks a 5/8” wire rope if it hooks accidentally onto a tree stump.

Modern hydraulic booms are also at a disadvantage on soft ground because the weight required to counterbalance their booms is too great to stop them from sinking.

Today, draglines are used to create or dredge large dams and farm ponds, but modern purpose-built monster draglines have been built for use in mining operations. A large one can reach depths of up to 80m, while some of the largest draglines can lift several hundred tonnes in a single scoop.

Source: Interview with Dragline owner-operator, Malcolm Smith

Copyright Theresa Sjoquist