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Port Otago Dredging Moving Forward

Port Otago Dredging Moving Forward

Port Otago Case Study

‘Eyes’ Under the water keep Port Otago dredging moving forward. Real-time underwater visualization using Trimble’s Marine Construction Software (TMC) and positioning technologies, help Port Otago control maintenance channel dredging in New Zealand.


Port Otago is located on the Otago Harbour, in New Zealand. It is the island’s primary export port and operates two wharf systems – Port Chalmers and Dunedin – both within Otago Harbour. The port moves over 200,000 TEU (Twenty-foot Equivalent Unit) containers and over 15 million tonnes of conventional cargo every year. Port Otago maintains the longest harbour channel in New Zealand with regular dredging services. The success of these dredging operations has helped increase productivity by allowing larger ships and greater freedom of movement within the channel.

Business Challenge

The dredging operation is essential in maintaining a consistent 8 metres through the shipping channel and turning circle. The channel is currently 8 meters (26 feet) deep with the strategic goal of expanding the port to 10 meters (33 feet) deep. The challenge of rivers feeding sediment and shingle in the harbour, tides and inconsistent seabed depth require guidance for the dredging operators to understand exactly where and when to dredge while preventing the removal of excess material


  • Dredge accurately and on time - Using Trimble Marine Construction (TMC) Software the operation is able to return to the exact location they left off at and quickly get back to dredging. With the help of TMC, the fleet can get within 10-20 cm (4 to 8 inches) accuracy and maintain a continuous dredging operation.
  • Real-time visualization - TMC gives operators an underwater 3D image of the operation so they know exactly where to dredge and to what depth via a user-friendly graphical interface using a green and red lines to signify where to dig and where to stop.
  • Maintain Dredging Resource Limitations - The port has limits to maintain resource consents to operate in the Otago Harbour. Over-dredging causes too much material to go out to sea, creating an excessive cost, removing just the required amount of material saves time and efforts of the operation.
  • Project transparency with accurate reporting - As-built dredge data is collected using TMC and project progress reports are created using Trimble Business Center - HCE. Reports are shared seamlessly via Dropbox.

Accurate and Time-saving Technology

The team at Port Otago needs to work efficiently and accurately, which is why they rely on Trimble Marine Construction Software to help them complete their job.

The port and team know the importance of accurately reaching the depth design

“Having our target reduced level is critical” Leon Snoeck, Dredge Operator shared. “If we are over dredging, we have too much material going out to sea and it is a cost” he continues. “If we are just removing the material we need to then it is a win-win for the port company”

Aside from material, Port Otago, has found Trimble Marine Construction Software to also help with positioning.

“Positioning time is quite significant with a dredging operation, so we don’t want to spend too much time positioning” Brant Lewinberg shared. The technology has allowed them to make systematically dredge to avoid missing targets or over dredging.


We're Looking at a 3D View of Our Work Underwater

Prior to the using TMC software and Positioning system the dredge operation relied on using manual efforts by using tide gauges and putting paint marks around the dipper arm of the digger. Using the technology they are able to get a view underwater to see the dig, materials, and the depth target.

“We can accurately dig to the design depth. No high spots, and we don’t need to stop. Very productive just because of your continuous operation of it. With the system, we can go back to the exact same place that we left the day before” Alex Wakefield, Dredgemaster said

A Step Forward

The technology has helped the port move forward with their strategic goals and dredging maintenance. The team explains that the visuals allow them to dredge accurately and save efforts where they can. The 3D image shown on the ship allows them to position and dredge confidently.

“It’s like having a camera underwater. I am able to get within 10-20 cm (4 to 8 inches) on the seafloor of our target depth. We can dig in one area, and then move across half a bucket and pick-up the spillage and cut at the same time,” Leon said.

Changing conditions like tide and shift of materials can make dredging consistently a challenge. “The Trimble system itself calibrates for the tide what our target depth is. It also has a pitch and roll which enables us to set the barge up accurately at any one time” Leon described.


Easy To Use

Operators at the port all shared the ease of use with Trimble Marine Construction software. They found it was easy to learn and never had any issues or problems arise during their digs. This makes project completion time to be on target and allows operators to confidently dredge.

“It just runs. We turn it on in the morning and we don’t have any major issues, a few little learning curves, but we are all brand new with the software too. But good support through SITECH.” Brandt Leeuwenburg shares. “We haven’t had any major issues.” he continues.

“Navigating around the Trimble System it’s really user-friendly, even for people who aren’t computer savvy, it is very easy to pick up. Such a tool that I am used to now, that I wouldn’t want to go back without it” Leon Snoeck explained.

Trimble has a range of solutions for dredging, placement, hydrographic surveying, visit to learn more.