Survey talk for any patch of missing data: whole pings lost to aeration, outer beams that fail detection over soft mud, or a sounder losing track for a few seconds on steep ground. Isolated dropouts are harmless when overlap covers them, but runs of them turn into holidays and infill lines. Operators watch the live display and slow down or adjust power and gain before they pile up.
Dropouts every time we cross the wake, keep clear of the dredger's track.
Also heard as
- drop-out
- data dropout
Related terms
Aeration
Air bubbles under the hull or across the transducer face that block sound and cause lost pings.
Holiday
A gap in survey coverage where no data was collected, which must be filled before the survey is complete.
Lost bottom
Said when an echo sounder stops tracking the real seabed and reports noise, a second echo or nothing.
Infill
A short extra line run to fill a gap in coverage, usually to clear holidays found during processing.