Bubbles swept beneath a hull by its bow wave, pitching or breaking seas, or trapped along a poorly faired transducer mount. Because air reflects and absorbs sound almost completely, a bubble layer over the face causes sudden loss of returns, noisy beams and missing pings. Remedies include mounting transducers deeper or on gondolas and keels, slowing down, and choosing line directions that keep the bow out of the sea.
Heading into the chop gives us aeration every third wave, turn the plan around and run it with the sea.
Also heard as
- bubble sweepdown
- bubble wash
Related terms
Dropout
Missing pings or beams where the sonar failed to record a valid depth, leaving gaps in the data.
Transducer
The device that turns electrical pulses into sound in the water and converts returning echoes back into signals.
Pole mount
A sonar transducer fixed on a rigid pole over the side or bow of a boat instead of built into the hull.
Weathered out
Unable to survey because wind, sea or swell would ruin data quality or make boat work unsafe.