Table of Contents

Route checks and under-keel clearance

A route check compares a route with the loaded data. It covers land, drying ground, the safety contour, charted dangers, regulated and protected areas, S-124 navigational warnings and chart coverage. With a draft, it also computes the under-keel clearance (UKC) along the route at each point's ETA. Three hosts run the same checks and report the same findings and codes:

In your own code, RouteChecker in the EncDotNet.S100.Navigation package runs every check on one PassagePlan and returns one RouteCheckReport, as all three hosts do. How a route check works explains which data each check reads, the time and keel rules, the verdict and each check's status.

The results are an aid for exploring the data, not for navigation.

What a check uses

  • The route. Each leg is a rhumb line or a great circle between two waypoints.
  • The corridor. Each leg's port and starboard cross-track limits (XTD) bound the area swept beside the track. They're half-widths: how far the corridor reaches to each side. A side without a limit uses 50 m. MCP and s100 route check can replace every leg's limits with one half-width.
  • The safety contour and safety depth. These are the mariner settings that also drive S-101 portrayal. SoundCharts uses Mariner Settings. MCP and the command line take them as arguments; the command line defaults to 30 m, the S-101 portrayal default.
  • The draft, squat and required UKC of each leg. They set the depth a leg's dangers are judged against, and the UKC check runs when every leg has a draft. See Keel.
  • The departure and speeds. Speeds give each point an ETA, and warnings, seasonal areas and S-104 water levels are judged at the ETAs. See Time for the time used where there's no ETA.

Finding groups

Each finding is in one of three groups:

Group Meaning
Must review Something on the track that needs a decision: land, drying ground, water shallower than the safety contour, a danger inside the limits, a prohibited area, a warning in force on the route, or UKC below your setting.
Check Something inside the limits or near the route that's worth a look, such as shoal ground beside the track, a danger just outside the limits, a caution area or a warning near the route.
Info Context that doesn't need action, such as an area or warning that isn't in force during the passage.

The summary names the worst group: "2 to review", "1 to check", or "No findings for your settings". A finding inside the limits but off the track is one group lighter than the same finding on the track.

Each finding has a code, a title, a meta line (leg, distance, feature and values), its leg, its distance from departure, a location (a point or a span of the route) and, when one is behind it, a feature reference you can open with Identify in SoundCharts or describe_feature over MCP.

Land, drying ground and coverage

These checks need no draft and no mariner settings.

Code Group When
route_check.crosses_land Must review The track crosses a LandArea, or a Coastline where no land area is charted.
route_check.crosses_drying Must review The track crosses a DepthArea that dries (DRVAL1 below the datum).
route_check.land_in_corridor Check Land reaches inside the cross-track limits, but the track doesn't cross it.
route_check.drying_in_corridor Check The same, for drying ground.
data.outside_chart_coverage Check The track leaves the DataCoverage of every loaded cell.

The charts are S-101 cells, S-401 inland cells and S-57 cells translated to S-101. Where cells overlap, only the finest cell at a place counts, so a coarse cell's generalised land doesn't fire where a finer cell charts water. Crossings of the track are exact. Ground that only reaches into the corridor is found at cross-sections every 10 m.

Depths and charted dangers

These checks run when the safety contour and safety depth are both set.

Code Group When
route_check.crosses_safety_contour Must review The track crosses depth, dredged or drying areas shallower than the safety contour, or another feature that raises the SafetyContour alert.
route_check.safety_contour_in_corridor Check Such areas or features inside the limits, off the track.
route_check.soundings_below_safety_contour Check Soundings no deeper than the safety contour inside the limits, outside water already shallower than it.
route_check.crosses_s102_shoal Must review The track crosses S-102 cells shallower than the safety contour.
route_check.s102_shoal_in_corridor Check Such S-102 cells inside the limits, off the track.
route_check.danger_in_corridor Must review A wreck, obstruction or rock shallower than the threshold, awash, or of unknown depth, inside the cross-track limits.
route_check.danger_near_route Check Such a danger within 0.1 NM beyond the limits.

Besides depth areas, every feature whose S-101 portrayal raises the SafetyContour alert is safety-contour ground: floating docks, hulks, pontoons, shoreline constructions, unsurveyed areas, and land charted as points or curves. An area is crossed or in the corridor as the depth areas are; a point or curve is crossed when the track passes within the track clearance (30 m) of it.

Soundings follow the portrayal's SOUNDG03: a sounding counts when it's no deeper than the safety contour. The safety depth only decides how the chart draws a sounding (bold when shallower), so a soundings finding notes it when its least depth is also shallower than the safety depth.

A danger is a Wreck, an Obstruction or an UnderwaterAwashRock:

  • Its depth is its valueOfSounding (VALSOU). Without one, it's the defaultClearanceDepth S-101 2.0 gives instead, as the portrayal's OBSTRN07 and WRECKS05 take it, unless the danger reaches the surface. The S-57 translation fills that attribute in for hazards without VALSOU.
  • One without a charted depth (above water, covering and uncovering, awash, or of unknown depth) always counts.
  • One with a depth counts when it's no deeper than the safety contour, as the portrayal's UDWHAZ05 judges it, or, on a leg with a draft, when it's shallower than that leg's draft + squat + required UKC. The meta line names the threshold that fired, the draft one when both do.
  • A danger counts wherever it lies, also inside water already shallower than the safety contour, where the safety-contour finding covers the stretch: UDWHAZ05 raises its alert either way.

A danger finding is located at the danger itself, and its distance is the point on the route nearest to it. A danger near a turn is reported once, on the closer leg. Shoal soundings or S-102 cells less than 100 m apart along the route make one finding.

Buoys, beacons, piles, platforms, bridges and other features whose S-101 portrayal raises the NavHazard alert are reported by where they lie from the track. These checks need no depth settings.

Code Group When
route_check.aid_to_navigation Check or Info An aid to navigation (a buoy, beacon, daymark, light float or vessel, or AIS aid) inside the cross-track limits; Info within 0.1 NM beyond them.
route_check.structure_on_track Must review A structure, such as a pile, dolphin, platform or fishing facility, within the track clearance (30 m) of the track line.
route_check.structure_in_corridor Check or Info A structure elsewhere inside the limits; Info within 0.1 NM beyond them.
route_check.overhead_on_route Check or Info A bridge, span, overhead cable or pipeline, or conveyor inside the limits; Info within 0.1 NM beyond them.

The route check runs the S-101 portrayal rules on the features in each leg's corridor, at the check's safety contour, and keeps the alerts they raise, so a hazard counts exactly when an ECDIS would raise the alert for it. Wrecks, obstructions and rocks are the dangers above. A feature type the check doesn't know is treated as a structure. The track clearance and the 0.1 NM near band are settings (--track-clearance and --nearby in s100 route check, trackClearanceMeters and nearbyDistanceMeters in check_route). Overhead features aren't judged against an air draft yet.

Regulated and protected areas

These checks need no draft. An area's date range or season is judged at the ETAs where it meets the route.

Code Group When
route_check.enters_prohibited_area Must review The track enters an S-101 area where entry is prohibited or restricted.
route_check.prohibited_area_in_corridor Check Such an area inside the limits, off the track.
route_check.restricted_area Check, Info or Must review Another S-101 restricted or military practice area, offshore production area, seaplane landing area or marine farm; Info when its restrictions don't bear on a passage, such as fishing or anchoring prohibited; Must review when the track enters an area to be avoided.
route_check.caution_area Check A caution area.
route_check.traffic_area Check, Info or Must review A precautionary area or submarine transit lane; Info for an inshore traffic zone; Must review when the track enters a traffic separation zone.
route_check.anchorage_area Check An anchorage area.
route_check.protected_area Check or Info An S-122 marine protected or restricted area. It's never Must review.
route_check.area_not_in_force Info The area's date range or season doesn't cover the ETAs.
route_check.area_kind_off Info The route meets areas of a kind whose indication is turned off; one finding per kind.

The S-101 areas are the ones whose portrayal raises the ProhAre alert, in the 13 kinds of the S-101 alert catalogue, plus precautionary areas. Areas charted as points count too. Each kind can be turned off (--areas-off in s100 route check, areaKindsOff in check_route; S-164 calls this the user selection of prohibited areas). The areas of a kind that's off aren't reported; instead one finding, worded as the catalogue words it, says the indication of some areas is off, with the kind and how many the route meets. The kinds are traffic_separation_zone, inshore_traffic_zone, restricted_area, area_to_be_avoided, particularly_sensitive_sea_area, caution_area, offshore_production_area, user_area_to_be_avoided, military_practice_area, seaplane_landing_area, submarine_transit_lane, anchorage_area and marine_farm.

S-124 navigational warnings

Each part of every loaded S-124 warning is compared with the corridor. A warning crosses the route when its line or area reaches the corridor. It's near the route when it's within 0.5 NM of the track, or when it's a point inside the corridor. Whether it applies is judged at the ETA where the route meets it, from its validity, its cancellation date, cancelling warnings and the latest in-force bulletin.

Code Group When
s124.on_route Must review The warning crosses the route and is in force while the vessel is there.
s124.near_route Check The warning is near the route and in force while the vessel is there.
s124.not_in_force Info The warning is on or near the route, but not in force while the vessel is there.
s124.cancelled Info The warning is on or near the route, but cancelled by the time the vessel is there, or left out of the latest in-force bulletin.

Each S-124 finding also carries the warning: its number, title, locality, validity, text, and when the vessel reaches and leaves it.

Under-keel clearance

With a draft on every leg, the UKC check samples the route and computes, at each sample's ETA:

UKC = charted depth + water level − draft − squat

and compares it with the required UKC (0 m when none is set).

  • Charted depth comes from S-102. Where there's no S-102, or a cell has no data, it comes from S-101: the shallowest covering dredged area, then depth area (DRVAL1), then a sounding within 250 m.
  • Water level comes from S-104 at the ETA, interpolated between time steps: grids first, then the nearest station within 10 km. Outside the S-104 extent or time range there's no water level, and the stretch is a gap.
  • Datums. When the depth and water-level vertical datums differ, the water level is reported but not applied, and the stretch is a gap.
  • Squat is a fixed allowance. It isn't modelled from speed, and S-111 currents aren't applied to ETAs.

Each sample has a state:

State Meaning
Meets your settings UKC is at least 0.5 m above the required UKC.
Tight UKC is less than 0.5 m above the required UKC.
Below your UKC setting UKC is below the required UKC.
No data No charted depth, or no water level to apply.

The verdict is the first of these that applies: water level ends before arrival, below your UKC setting, incomplete data, meets your settings but tight, meets your settings. A departure window sweeps departures across the S-104 time range and lists the runs of departures that meet your settings. For how samples are spaced and what the result reports, see Under-keel clearance.

Confidence

Confidence is reported separately from the state. A stretch can meet your settings and still be lower confidence. The reasons are:

Reason Meaning
charted_depth_from_s101 The depth is from S-101 because no S-102 covers the stretch.
datum_unconfirmed The depth or water-level datum isn't declared, or isn't an S-100 code, so they can't be confirmed to share a reference. The water level is applied anyway.

SoundCharts draws a lower-confidence stretch in its state's colour, dashed. The verdict follows the clearance; the confidence reasons qualify it and never replace it.

Clearance findings

The UKC check turns the stretches behind its verdict and confidence into findings:

Code Group When
clearance.below_setting Must review A stretch where UKC is below the required UKC.
confidence.charted_depth_from_s101 Check A stretch where the charted depth is from S-101 because no S-102 covers it.
confidence.datum_unconfirmed Check A stretch where a depth or water-level datum isn't declared, so they can't be confirmed to match.
data.water_level_ends Check The water-level data ends before the vessel reaches a stretch, so the water level isn't applied there.
data.water_level_starts_late Check The water-level data starts after the vessel passes a stretch.
data.no_water_level_coverage Check A stretch outside every water-level dataset's coverage.
data.water_level_no_data Check A stretch inside water-level coverage where the data has no value.
data.datum_mismatch Check The water level's datum differs from the charted depth's, so it isn't applied.
data.no_charted_depth Check A stretch with no charted depth from S-102 or S-101.

Received routes and Copy to edit

A route opened from a file is a received route. It's read-only, so a check reports on the route as its author planned it.

  • Only your check settings can change: draft, squat, required UKC and departure. They're yours, not the route's. SoundCharts keeps them on your computer under the route ID and edition (an RTZ route's under its file path), and exports them only when you ask.
  • Speed and cross-track limits are route values. They stay as the file gives them.
  • Copy to edit makes an owned, editable copy with a new route ID, a reference to the source's ID and edition, edition 1 and status Planned. What SoundCharts' route can't hold is kept and written back when you export the copy in the same format.

s100 route check reads the file's values and applies any options you pass to every leg, so a CI run checks the route as it was received unless you say otherwise.

Route file formats

Format Versions Read Write
S-421 (GML) 1.0 SoundCharts, MCP, s100 route check SoundCharts, MCP
RTZ (IEC 61174 Annex S) 1.0, 1.1, 1.2 SoundCharts, MCP, s100 route check SoundCharts, MCP (1.2 by default)

Both formats give waypoints, leg geometry (rhumb line or great circle), cross-track limits, draft, static UKC, speeds and the departure. Neither has a squat allowance. Speeds and the departure come from the route's planning schedule: the first calculated schedule, else the first manual one.

RTZ differs from S-421 in a few ways:

  • A waypoint's leg in RTZ describes the leg arriving at it, so leg i is read from waypoint i+1.
  • Cross-track limits are nautical miles in RTZ and metres everywhere else.
  • Draft is the deeper of the forward and aft draughts.
  • A leg with no speed takes the speed its ETD and ETA imply.
  • RTZ has no route ID or edition, so an RTZ route is known by its file.

The EncDotNet.S100.Routes.Rtz package reads and writes RTZ, and EncDotNet.S100.Datasets.S421 reads and writes S-421.

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