Blueprint Subsea Starfish 453OEM, Системное руководство

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StarFish 453OEM
System Manual
17
4.10. Tips For Good Imagery
Vessel Speed
When operating the StarFish, remember that it is “pinging” at a fixed rate (depending on range). The faster you
move the sonar transducers over the seabed, the more compressed images will appear on the display.
For long ranges, try to operate at speeds between 1 and 3 knots, while shorter ranges can be used with speeds of
3 to 6 knots.
Water Depth
The depth of water beneath the sonar is an important factor to consider when interpreting heights of submerged
objects from their acoustic shadows.
In shallow water, acoustic shadows from targets appear very elongated (like shadows cast from objects at sunset),
while in deep water
the seabed will appear more as a “birds - eye” type view with minimal shadows.
Mounting Position
The position and method of mounting the transducers on the hull/platform is probably one of the biggest factors
in determining overall image quality. As discussed in previous sections, the transmitter and receiver faces on the
transducer should…
•
Have no obstructions in their acoustic beams that may cause shadows or reflections.
• Be clear of any turbulence or cavitation from the hull in front of them.
•
Be clear of turbulence or aeration caused by the platforms thrusters/propeller.
Boat Navigation
When surveying an area, think about the course you will steer your platform/vessel. Try to divide the area into a
grid of long straight runs, with 180° turns at the end.
Remember that as the sonar turns, the acoustic beams from the inside of the turn will overlap, while the outside
ones will be covering more seabed
– consequently the imagery produced will appear distorted and hard to
interpret in these areas.
Try and avoid the aerated water left in the wake of other boats, as this will be acoustically visible for some time
should you cross through it with your sonar.
Waves, Wake and Surface Chop
As some of the acoustic energy transmitted from the StarFish transducers is beyond its 60° vertical beam-width,
it is possible that it may be reflected off the underside of the surface of the water if you are operating close to the
surface. This may cause the sonar imagery to appear be distorted due to waves and surface chop on the water.
Remember that when operating the StarFish sonar your own safety is paramount and should not be
compromised trying to achieve good sonar imagery.