The main pattern of parallel lines that collects the bulk of the data. Mainscheme spacing is chosen to give full coverage with the required overlap for multibeam, or the specified line interval for singlebeam. Everything else (crosslines, splits, infills, developments) is measured against or added to the mainscheme, and statistics such as crossline percentage are quoted as a ratio of mainscheme mileage.
Mainscheme's done for the eastern block, we'll knock out crosslines this afternoon when it flattens out.
Also heard as
- mainscheme
- main scheme
Related terms
Line plan
The set of pre-planned survey lines, with spacing and orientation, that a vessel follows to achieve the required coverage.
Crosslines
Survey lines run across the mainscheme lines so the two data sets can be compared as an independent check.
Splits
Extra survey lines run halfway between existing lines to tighten spacing over a shoal or suspicious spot.
Infill
A short extra line run to fill a gap in coverage, usually to clear holidays found during processing.
Coverage
The portion of the seabed actually measured or imaged by a survey, expressed as a percentage of the area.