The most demanding order in the international survey standard. It allows 1 m horizontal uncertainty and vertical uncertainty built from a = 0.15 m and b = 0.0075, requires detection of cubic features larger than 0.5 m, and calls for 200 percent feature search and 200 percent bathymetric coverage. It is reserved for berths, locks and dredged channels where ships sail with very little water under the keel.
Port wants Exclusive Order on the container berth, so plan two full passes with the multibeam and tight crosslines.
Two hundred percent coverage usually means two independent passes, often on different days, so budget the boat time before quoting Exclusive Order.
Do not mix it up with
- Special Order: Special Order allows 2 m horizontal uncertainty, 1 m features and 100 percent coverage; Exclusive halves the feature size and doubles the coverage.
Related terms
Special Order
A survey order for harbours and channels where under-keel clearance is critical, with full coverage and 1 m feature detection.
Order 1a
A survey order for coastal waters and fairways where features matter but under-keel clearance is less critical.
S-44
The international minimum standard for hydrographic surveys, setting uncertainty, detection and coverage limits by order.
Feature detection
The ability of a survey system to find seabed objects of a stated minimum size, usually given as a cube edge length.
Coverage
The portion of the seabed actually measured or imaged by a survey, expressed as a percentage of the area.