Green Island Jetty Hydrographic Survey

How QOffshore delivered high-density bathymetry around an operational island jetty to support engineering, charting and future maintenance for Tailored Spatial Solutions.

CLIENT

Tailored Spatial
Solutions

REGION

Green Island, Cairns, QLD

FIELDWORK

28-29 August 2025

QOFFSHORE ROLE

Hydrographic survey
subcontractor

SERVICE

Jetty & approach MBES

SURVEY AREA

86,675 m²

RESOLUTION

0.25 m bathymetric grid

OUTPUTS

DTM, contours, spot depths & charts

The client issue

Tailored Spatial Solutions needed an accurate seabed model around Green Island Jetty and its approaches to support engineering assessment, operational planning and future maintenance. The survey had to capture complex near-jetty bathymetry and sharp depth transitions while remaining consistent with the project hydrographic reference framework.

The practical question

How can the jetty and approaches be mapped with enough density and control to support reliable engineering, charting and maintenance decisions?

The survey challenge

Jetty and nearshore access

Survey lines had to work around structures, shallow areas and reefinfluenced seabed without compromising coverage.

Precise survey control

Bathymetry had to be referenced to GDA2020 / MGA Zone 55 and Lowest Astronomical Tide with independent GNSS checks

Large depth transition

The mapped seabed ranged from about +0.62 m to -26.58 m LAT and still required one consistent high-resolution surface.

What QOffshore provided

Working for Tailored Spatial Solutions, QOffshore mobilised a compact aluminium workboat with a NORBIT iWBMS Tx multibeam system, SBG INS and dual GNSS antennas. Qinsy supported real-time acquisition and quality control, while Qimera was used for cleaning, validation and final surface generation.

Establish control

Mobilise the vessel, measure offsets, verify GNSS control and establish the project vertical reference

Acquire dense MBES

Run overlapping multibeam lines around the jetty and approaches with real-time quality checks.

Process and validate

Review navigation and attitude, clean soundings and generate a consistent 0.25 m surface.

Chart and deliver

Produce DTM, contours, spot depths and final hydrographic charts for project use.

86,675 m²

SURVEY AREA

192.5 million

ACCEPTED SOUNDINGS

0.25 m

GRID RESOLUTION

2 days

FIELD ACQUISITION

DECISION-READY OUTPUTS

Outcome and client value

The survey produced a high-fidelity bathymetric model around the jetty and approaches, with independent
GNSS checks showing close agreement and no systematic bias. Tailored Spatial Solutions received a
consistent dataset suitable for engineering review, charting, maintenance planning and future comparison.

THE SUCCESS STORY

Dense MBES coverage converted a complex jetty approach into a clear, geodetically controlled seabed model that engineers and operators could use directly.

Why it mattered

CLIENT VALUE

One controlled survey provided a detailed depth picture across the jetty and approaches - from shallow near-structure areas to the deeper channel - reducing uncertainty for engineering and maintenance planning.

Green Island Jetty Hydrographic Survey