Bathymetry

Bathymetry is the study of underwater depth. The settings here affect how underwater features are displayed. Note that other settings, such as the Safety Depth, Safety Contour, Shallow Contour and Deep Contour also affect display of underwater features.

Use these features with care! Incorrect use can result in confusing display of depth related information. If you are unsure about the correct use of these features, leave the settings at their default values.

Settings

Bathymetric ENCs

• Show bENC Overlays (Only SEAiq Pilot) : Enables display of Bathymetric overlays (bENCS). In some areas of navigation where detailed depth information is required for safe navigation, special digital charts called Bathymetric ENCs (bENCs) have been created. bENCs contain detailed information about depth not available in the normal charts for these areas. The bENCs are specialized in that they only contain bathymetric information and do not include other navigation information such as aids to navigation or bridges. Getting the full picture of both the bathymetric information and navigation requires displaying information from both bENCs and the corresponding ENCs.

  When this setting is enabled, SEAiq modifies display of standard ENCs to replace underwater features (such as depth soundings, underwater contours, underwater depth areas, and dredged areas) with data from a bENC chart. Note that ENC navigation features are layered above bENC so that items such as buoys remain visible.

  Use this feature with care. In some situations it can be confusing. If you are uncertain about the accuracy of the display, we recommend disabling this feature.

  Below are some further notes/caveats:

  • When enabled, you will see (bENC Enabled) in the bottom-right corner of the display.
  • Enabling and disabling the feature will trigger SEAiq to reprocess charts. There may be a delay while this happens.
  • bENCs must not overlap each other, even if they have different compilation scale. In fact, the bENC charts (if there is more than one loaded) should normally all be at the same compilation scale.
  • Small-scale charts sometimes have inaccurately placed land area (LNDARE), built-up area (BUAARE), and river (RIVERS) features. So these features are placed in the overlay for compilation scales less than 1:15k and in the "underlay" for smaller scales.

• Hide Unsurveyed Area Features in bENCs (Only SEAiq Pilot) : When enabled, causes Unsurveyed Area (UNSARE) features to not be displayed in bENC overlays. This allows features from an underlying ENC to be shown. Note that in some situations this can mix ENC and bENC features in ways where the boundaries are hard to distinguish.

S-102 bENCs

• Show IHO S-102 bENCs (Only SEAiq Pilot) : When enabled, IHO S-102 bENCs will be displayed.
• Style (Only SEAiq Pilot) : Select between vector and raster style presentation for S-102 bENCs. Vector display is normally recommended.
• Sun Illuminated Raster (Only SEAiq Pilot) : When enabled, the raster display of charts will be shaded to give idea of the sea-bed contour. This option is only effective when in raster mode and using day-time color palette.
• Contour Interval (Only SEAiq Pilot) : Set contour interval for S-102 bENCs. The minimum allowed value is 0.25m.
• Precise Mariner Contours (Only SEAiq Pilot) : When enabled, contour lines for precise value of Safety Contour, Shallow Contour, and Deep are added to the display. This ensures that the coloring of depth areas is precise. However, this also means that there may be more contours than otherwise indicated by the differences in depth. In particular, if any of the mariner-designated contours does not exactly match the regular intervals, then an extra contour is added at exactly that depth.

• Align to Safety Contour (Only SEAiq Pilot) : When enabled, contours are all aligned to the safety contour for S-102 bENCs.

  For example, if the Safety Contour is 6.75m and the contour interval is 1m then all contours will be X.75m.

• Interpolate Contour Lines (Only SEAiq Pilot) : When enabled, contour lines will be interpolated to their estimated location within grid squares. This can cause the contour lines to be adjusted up to one grid contour from their location specified in the data file. Without this option enabled, the contours follow the grid squares.
• Disable Hi-Res Cells (Only SEAiq Pilot) : When enabled, S-102 chart cells with 5x5m or higher resolution will be disabled and not used. This can help in situations where highest resolution cells may have patch-work coverage from use of lower resolution survey methods. The patch-work coverage can result in a display that mariners find unhelpful. Lower resolutions cells will be used instead, which normally will not exhibit the patch-work coverage.
• Filter Areas Above Water Line (Only SEAiq Pilot) : When enabled, S-102 grid points which are above the water line will be filtered from the cell. This is to address issues where S-102 cells have extensive coverage of above-waterline areas and these are obscuring shoreline features.

• Heat Map (Only SEAiq Pilot) : Show recent changes as a so-called heat map. Areas of shoaling are displayed as red. Areas of deepening are shown in blue. Areas of no or very small change are shown in green.

  When Sun Illuminated Raster option is enabled, the areas are shaded according to their relative depths (increasing depth is shown as valleys, decreasing depths are shown as hills. The height differences are emphasized with a 5x increase in differences.

• Heat Map Duration (Only SEAiq Pilot) : Maximum age of a chart in days to be included in the heat map presentation. Default is 0 days (no limit).
• NOAA S-102 Products : Support for downloading S-102 products for USA from NOAA.

Tide

• Tidal Adjustment : Provide adjustment to depths based on current tides. See below for more information.
• Fill Tidal Adjustment : This allows you to fill based on currently selected tide adjustment. Requires that you have selected an object with tidal data.
• Tidal Adjustment Warning (Only SEAiq Pilot) : When enabled and tidal adjustment is active, a large warning is shown in the lower center of the display. It is shown in addition to similar warning the lower-right (which is always displayed). The large display is only shown if the display size is large enough.

Safety Depth & Contour

• Draft (Only SEAiq Pilot) : Manual setting for draft of the vessel. This can be used to help configure Safety Depth and Safety Contour.
• Under Keel Clearance : Here you can specify how much additional UKC you want to use. The UKC can be given either as a fixed depth or a percentage of the vessel's draft. For instance, in some locations, it is common practice to use 10% of a vessel's draft as UKC.
• Shallow Contour Delta (Only SEAiq Pilot) : When set, this is subtracted from Safety Contour to set the Shallow Contour.
• Deep Contour Delta (Only SEAiq Pilot) : When set, this is added to Safety Contour to set the Deep Contour.
• Calculated Depth & Contour Settings : This is the calculated Shallow Contour, Safety Depth, Safety Contour, and Deep Contour, based on the draft, UKC, and deltas.
• Current Depth & Contour Settings : This shows the current value(s) for the Shallow Contour, Safety Depth, Safety Contour, and Deep Contour These are the same as given on the Vector Charts settings. When values are equal, they are elided.
• Update Chart Settings : Press this button to change current Shallow Contour, Safety Depth, Safety Contour, and Deep Contours values to the calculated ones.
• Automatic Update (Only SEAiq Pilot) : When enabled, the Shallow Contour, Safety Depth, Safety Contour, and Deep Contours are updated automatically when Own-Ship draft is changed. Additionally, the current Safety Contour is always shown in the bottom-right of the chart display.

Overlays

• Show Overlays (Only SEAiq Pilot) : When enabled, overlays are displayed.

• Declutter Soundings (Only SEAiq Pilot) : When enabled, soundings in overlay files (Autocad DXF, Shapefile, and XYZ files) are decluttered using a proprietary algorithm. This algorithm applies SCAMIN values to each sounding so as you zoom in/out the most important soundings are displayed.

  This feature is considered experimental and should only be used with care. If uncertain, leave this feature disabled.

• Mask Soundings from Old Overlays (Only SEAiq Pilot) : When enabled, overlay files (Autocad DXF, Shapefile, and XYZ files) are organized according to dates and newer soundings are shown in preference to older soundings.

  Files are organized by searching for date expressed as 8 decimal numbers in YYYYMMDD format, where YYYY, MM, and DD correspond to years, months, and days.

  This feature is considered experimental and should only be used with care. If uncertain, leave this feature disabled.

• Mask Soundings Range (Only SEAiq Pilot) : Range to use when calculating sounding masks. Default is 100m.

  This feature is considered experimental and should only be used with care. If uncertain, leave this feature disabled.

Admiralty Information Overlays

• Enable (Only SEAiq Pilot) : Enabling this causes AIO overlays to be shown when available. In most cases, AVCS AIO cell permits are required and the current AIO distribution should be installed.

  AIO notices will be shown based on the AVCS ENC's that are currently active. To read the information in the notice, you can can double tap in a notice and choose the item(s) marked with (AIO).

• Allow Unencrypted (Only SEAiq Pilot) : Enabling this allows AIO overlays to be used with unencrypted cells. The default is to only allow encrypted cells from GB (UKHO AVCS) data server. This option is only provided for testing purposes; AIO is required to only be used with charts licensed from UKHO.

Tidal Adjustment

In situations where tidal height is important to navigation the mariner may find it useful to adjust display of bathymetric features to account for the current tide.

This feature works both with and without bENCs.

The default setting is 0, which causes all bathymetric information to be displayed unmodified. This value may be changed to positive or negative values. Whatever value is selected will be added to the depth in the chart. If this is set to 10m, then a 15.3m sounding will be changed in the display to 25.3m.

Since depth information are typically reference a low tide datum, you will normally use positive adjustments that correspond to a higher tidal state. A situation where a negative adjustment would make sense is an extreme low tide.

After changing the setting, SEAiq will proceed to update any chart you display, in order to reflect the adjustment. There may be some delay as the chart is re-processed.

If you are unsure about use of this feature, leave it set to the default value of 0.

• When enabled, you will see (Tidal Adjustment) in the bottom-right corner of the display.
• If you ever want to change back to the default, just edit this setting back to the original default of 0 (no adjustment).
• All other depth related display information is updated accordingly, including Shallow, Safety, and Deep Contours. Soundings are reprocessed to account for the new effective Safety Depth.
• When Sounding Range and Tidal Adjustment are both used, then the Tidal Adjustment is applied to a sounding before determining if the sounding should be displayed. Changing the Tidal Adjustment may affect what soundings are displayed.
• This feature must be used with care. Tides are always changing. The setting you used an hour ago is likely no longer accurate.
• This is a static setting. By default, SEAiq does not attempt to dynamically track tidal changes. If you want to change it further because tidal height has changed, you can do so manually. Alternatively, see Settings / Tides / Dynamic Tidal Adjustment can be used to automatically update the adjustment.
• This setting is global in effect. Correct use may cause display of bathymetric information in one area to be more accurate. However, display of information in most other locations is likely to be less accurate.
• It is up to the mariner to check the vertical datum to determine the correct reference datum to use when setting the adjustment.
• Only depth related features are affected by this setting. Any shore features (such as the height of lights) are not affected.
• When interrogating meta-data information using "Details for this Location", the meta-data is displayed unmodified (no tidal adjustment).

Safety Depth / Contour

The following settings are used to update the values of the Safety Depth and Safety Contour chart display settings. This feature is used to simplify calculations for the Safety Depth and Safety Contour settings. It is always possible to set the values directly by going to the Vector Charts settings and editing the values there.

Before using these settings, you should normally ensure the dimensions for Own-Ship have been set in the Own-Ship settings, in particular the Draft.

Display Bathymetric ENCs (bENCs)

In some areas of navigation where detailed depth information is required for safe navigation, special digital charts called Bathymetric ENCs (bENCs) have been created. bENCs contain detailed information about depth not available in the normal charts for these areas. The bENCs are specialized in that they only contain bathymetric information and do not include other navigation information such as aids to navigation or bridges. Getting the full picture of both the bathymetric information and navigation requires displaying information from both bENCs and the corresponding ENCs.

When this setting is enabled, SEAiq modifies display of standard ENCs to replace underwater features (such as depth soundings, underwater contours, underwater depth areas, and dredged areas) with data from a bENC chart. Note that ENC navigation features are layered above bENC so that items such as buoys remain visible.

Use this feature with care. In some situations it can be confusing. If you are uncertain about the accuracy of the display, we recommend disabling this feature.

Below are some further notes/caveats:

• When enabled, you will see (bENC Enabled) in the bottom-right corner of the display.
• Enabling and disabling the feature will trigger SEAiq to reprocess charts. There may be a delay while this happens.
• bENCs must not overlap each other, even if they have different compilation scale. In fact, the bENC charts (if there is more than one loaded) should normally all be at the same compilation scale.