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Tamaki Strait

Client:

Land Information New Zealand

Duration:

5 months

Budget:

NZD$2m

Project Date:

2016/17

Background

In 2016, iXblue Australia performed a Tamaki Strait marine survey for Land Information New Zealand (LINZ).  The Tamaki Strait is a busy waterway located approximately 25 kilometres east of Auckland, and is situated between the islands of the Inner Hauraki Gulf.  The majority of the area was last surveyed in the late 1960s using single beam echosounder technology.

Requirement

The main aim of the survey was to identify all hazards that had the potential to cause harm or damage to any vessel navigating in these waterways.  The resultant survey data would facilitate LINZ with publishing a modern and up to date nautical chart of the region, which would allow all mariners to navigate with increased knowledge and safety.  The survey was to be completed by mid 2017.

Challenges

The survey area is characterised by large areas of shallow water and many miles of coastline.  When surveying with a multi-beam echo sounder, this requires great care and attention by the survey crews in order to avoid accidental grounding and damage to the sonar system.

Predominant west, south westerly winds during the survey required much last minute planning to operate in protected and sheltered areas throughout the survey whilst maintaining a high rate of effort.

A significant mechanical issue with the survey vessel engine lost several weeks whilst repairs were made.

Survey Solution

  • To ensure we provided LINZ with the best possible outcomes, we opted for a single vessel solution fitted with high resolution Multibeam echosounder in a dual head configuration, mobile laser scanning and digital camera imagery to undertake the data capture for the survey.
  • To ensure data quality was maintained throughout this project, we conducted equipment and patch testing during mobilisation, and further patch testing throughout the survey and prior to demobilisation.  This involved checking the fine alignment between the motion sensor and the sonars.
  • The survey team were accommodated in a rented house in the port of Westhaven during the fieldwork phase of the project.

Outcome

The survey field work was completed in early March and the final survey report was delivered by mid-year.

In all, over 4,500 survey line miles were required to complete the survey project.  With the exception of the engine fault, the project ran smoothly, safely and to schedule.  The data captured during the survey allows LINZ to publish a highly accurate and valuable chart that will increase the navigational safety of all mariners – professional and recreational, who will use these waterways for many decades to come.

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