Hydrographic Survey FAQs
How Does a Multibeam Echosounder Work?
A multibeam echosounder is a sophisticated sonar system designed to produce comprehensive maps of the seabed. It emits a fan-shaped array of sound waves from a transducer affixed to a survey vessel's underside, projecting these pulses downward. Upon reaching the seafloor, the sound waves are reflected back and captured by the transducer.
The device then calculates the time taken for these waves to return, and employing the known speed of sound in water, it can precisely determine the seabed's distance. This facilitates accurate measurement of water depth and results in finely detailed maps of underwater topography. The term "multibeam" pertains to the echosounder's capacity to release multiple beams simultaneously, allowing it to survey a broad section of the seabed in a single pass.
What are Inertial Navigation Systems?
Inertial Navigation Systems (INS) are advanced technological tools that utilise motion and rotation sensors, such as accelerometers and gyroscopes, to compute an object's positional data, orientation, and velocity without external reference points.
These systems operate independently, unlike GPS, which requires satellite signals and are invaluable in scenarios where GPS reliability is questionable or non-existent, for example, underwater. This data is then used for precise positioning and orientation of surveying equipment.
INS technology has revolutionised surveying by enabling accurate mapping and measurement of underwater features, even in challenging environments.
What Kind of Information Can Be Gathered from a Hydrographic Survey?
Hydrographic surveys provide intricate visualisations of the seabed bathymetry, objects and human-made structures. The data gathered can also be used to assess sedimentation levels, navigability, dredging requirements and infrastructure development.
What Are the Risks Associated with a Hydrographic Survey?
Conducting hydrographic surveys involves risks such as adverse weather, inclement sea conditions, and uncharted underwater obstacles.
As with any operations in the marine environment, the survey crew may face physical hazards while working near or on the water. These include slips, trips and falls on slippery decks or unsteady platforms. All site-going personnel must be suitably trained and equipped with appropriate safety gear to manage these risks.
How Long Does a Hydrographic Survey Take?
The duration typically depends on the size and complexity of the area being surveyed. Small areas can generally be completed in a matter of hours while more extensive campaigns may take weeks or even months.
It is important to plan ahead and allow sufficient time for both data collection and post-processing. Weather and sea conditions can also impact the length of a survey, as they may limit safe working hours or cause delays.
How Much Does a Hydrographic Survey Cost?
The cost of a hydrographic survey varies depending on the size and complexity of the area being surveyed, as well as the equipment used. Generally speaking, smaller surveys tend to be more affordable than larger projects due to the reduced amount of data collected, although this may not always be the case.