Licences & sources

CoveGuard — Third-Party Licenses

This file documents third-party assets included in CoveGuard that require attribution under their respective open licenses.

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Noto Sans (assets/google_fonts/)

The typeface CoveGuard uses to typeset its PDF exports (the logbook and the charter handover protocol). Bundled DELIBERATELY rather than downloaded: with no signal the document fell back to Helvetica, which has no Czech letters, and every diacritic came out as a hollow box.

• Files: NotoSans-Regular.ttf, NotoSans-Bold.ttf (fetched from fonts.gstatic.com — the very files the printing package would otherwise download at runtime).
• Author: The Noto Project Authors (https://github.com/notofonts/latin-greek-cyrillic)
• Licence: SIL Open Font License 1.1 — the full text sits next to the font in assets/google_fonts/OFL.txt.
• What the licence requires: keep the copyright and licence text (met by that file), do not sell the font on its own, and rename it if it is ever MODIFIED. CoveGuard does not modify the font in any way.

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Knot Illustrations (assets/knots/)

Step-by-step knot illustrations guiding how each knot is tied. Sourced from Wikimedia Commons (each file under its own license — attribution shown in-app on every knot card and listed below) and from public-domain works. All files were resized / recompressed for the app (the bowline GIF scaled to 380 px and the figure-eight converted from WebM to a 340 px GIF, animation preserved); no other changes. Creative-Commons files remain under their respective licenses; ShareAlike modifications (resize / format conversion) stay under the same license.

CC BY-SA 2.5/3.0 and GFDL dual-licensed files (rolling hitch, anchor bend, alpine butterfly, constrictor) are used under their CC BY-SA component.

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IALA Buoy Photos (assets/buoys/)

Buoy photographs are sourced from Wikimedia Commons under Creative Commons licenses. All photos are used unmodified (thumbnails resized by Wikimedia CDN). Original sources and authors are listed below.

Licence summary

CoveGuard is distributed under a proprietary licence. The CC BY-SA photos are display assets only — they are not modified and distributed as standalone files; they are bundled in the app for display purposes. Attribution is provided here and in-app (ialaImageCredits string in the IALA buoyage reference screen).

Per-photo attribution

• port_hand_a.jpg
  • File: Port Hand Buoy in the approaches to Port Qasim (2), 07.06.2021.jpg
  • Author: Muhammad Siddique Baloch
  • License: CC BY-SA 4.0
  • Source: https://commons.wikimedia.org/wiki/File:Port_Hand_Buoy_in_the_approaches_to_Port_Qasim_(2),_07.06.2021.jpg
• starboard_hand_a.jpg
  • File: Starboard Hand Buoy in the approaches to Port Qasim, 07.06.2021.jpg
  • Author: Muhammad Siddique Baloch
  • License: CC BY-SA 4.0
  • Source: https://commons.wikimedia.org/wiki/File:Starboard_Hand_Buoy_in_the_approaches_to_Port_Qasim,_07.06.2021.jpg
• north_cardinal.jpg
  • File: Sconce north cardinal buoy — geograph.org.uk — 3465306.jpg
  • Author: David Dixon / geograph.org.uk
  • License: CC BY-SA 2.0
  • Source: https://commons.wikimedia.org/wiki/File:Sconce_north_cardinal_buoy_-_geograph.org.uk_-_3465306.jpg
• south_cardinal.jpg
  • File: The "Egilsay Graand" South cardinal buoy — geograph.org.uk — 1885220.jpg
  • Author: Walter Baxter / geograph.org.uk
  • License: CC BY-SA 2.0
  • Source: https://commons.wikimedia.org/wiki/File:The_%22Egilsay_Graand%22_South_cardinal_buoy_-_geograph.org.uk_-_1885220.jpg
• east_cardinal.jpg
  • File: NE Shingles east cardinal buoy — geograph.org.uk — 3465286.jpg
  • Author: David Dixon / geograph.org.uk
  • License: CC BY-SA 2.0
  • Source: https://commons.wikimedia.org/wiki/File:NE_Shingles_east_cardinal_buoy_-_geograph.org.uk_-_3465286.jpg
• west_cardinal.jpg
  • File: West Bramble cardinal buoy — geograph.org.uk — 1937854.jpg
  • Author: Peter Facey / geograph.org.uk
  • License: CC BY-SA 2.0
  • Source: https://commons.wikimedia.org/wiki/File:West_Bramble_cardinal_buoy_-_geograph.org.uk_-_1937854.jpg
• safe_water_fairway.jpg
  • File: Munlochy Shoal "Safe Water" Navigation Buoy — geograph.org.uk — 1195631.jpg
  • Author: geograph.org.uk contributor
  • License: CC BY-SA 2.0
  • Source: https://commons.wikimedia.org/wiki/File:Munlochy_Shoal_%22Safe_Water%22_Navigation_Buoy_-_geograph.org.uk_-_1195631.jpg
• isolated_danger.jpg
  • File: Cardinal marks.jpg
  • License: CC BY-SA 3.0
  • Source: https://commons.wikimedia.org/wiki/File:Cardinal_marks.jpg
• special_mark.jpg
  • File: Nauticus buoy march 2009.JPG
  • License: Public domain
  • Source: https://commons.wikimedia.org/wiki/File:Nauticus_buoy_march_2009.JPG
• new_danger_emergency_wreck.jpg
  • File: Cardinal buoys waiting for deployment on Phares et Balises parking.jpg
  • License: CC0 1.0 Universal
  • Source: https://commons.wikimedia.org/wiki/File:Cardinal_buoys_waiting_for_deployment_on_Phares_et_Balises_parking.jpg
• port_hand_b.jpg
  • File: Small green lateral buoy (IALA region A).jpg
  • License: CC BY-SA 3.0
  • Source: https://commons.wikimedia.org/wiki/File:Small_green_lateral_buoy_(IALA_region_A).jpg
• starboard_hand_b.jpg
  • File: The Red and the Green — geograph.org.uk — 1475771.jpg
  • Author: geograph.org.uk contributor
  • License: CC BY-SA 2.0
  • Source: https://commons.wikimedia.org/wiki/File:The_Red_and_the_Green_-_geograph.org.uk_-_1475771.jpg

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DHMZ ALADIN-HR Weather Data

Wind forecast data for the Adriatic region is sourced from the ALADIN-HR numerical weather prediction model operated by the Državni hidrometeorološki zavod (DHMZ) — Croatian Meteorological and Hydrological Service.

CC BY 4.0 Attribution requirement

When wind forecast data from ALADIN-HR is displayed in CoveGuard, the following attribution is shown to the user:

Weather data: ALADIN-HR by Državni hidrometeorološki zavod (DHMZ) — CC BY 4.0

This attribution appears:

• In the wind/weather overlay layer on the map (attribution chip)
• In the About CoveGuard dialog (More → About)
• In this file

CC BY 4.0 license text: https://creativecommons.org/licenses/by/4.0/

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IALA Buoyage System

The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) buoyage system descriptions are in the public domain as international maritime standards. Reference data in lib/features/reference/data/iala_data.dart is compiled from IALA publication No. 1083 (public domain).

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Sentinel-2 cloudless satellite tile (assets/tiles/)

The onboarding demo (lib/features/onboarding/demos/) shows a real anchorage on a real satellite backdrop. Online it streams Esri World Imagery over the network (see the next section). Offline it falls back to a single tile that ships inside the APK, so the demo never ends up as an empty canvas on a boat with no signal.

CC BY 4.0 attribution requirement

Sentinel-2 cloudless 2024 by EOX IT Services GmbH (contains modified Copernicus Sentinel data 2024) — CC BY 4.0

CC BY 4.0 license text: https://creativecommons.org/licenses/by/4.0/

Where the user actually sees it (since 2026-08-12): the attribution is rendered in the bottom-left corner of the demo canvas (_AtribucePodkladu in lib/features/onboarding/demos/demo_bay_canvas.dart), and it names whichever basemap is on screen at that moment — the bundled Sentinel-2 tile when the device is offline, Esri when it is online. Before that date the attribution existed only in this file, which the user never opens; a licence notice nobody can see does not satisfy CC BY. The wording is deliberately not translated — it is the licensor's own, same rule as the weather-source line on the map (map_screen._wxModelCc).

The same product is already used for the offline satellite base map, which is downloaded to the device on demand rather than bundled; this section covers the one tile that is redistributed inside the application package.

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Esri World Imagery (streamed, never bundled)

The satellite base map — on the live map and in the onboarding demo — is served over the network from Esri World Imagery (https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/).

No Esri tile is shipped inside the application package, and the offline map download (OfflineRegionsService.tileLayers) pulls Sentinel-2, never Esri. Bulk caching or redistributing Esri imagery would breach their terms of service.

On-device caching — this section used to be wrong (fixed 2026-08-12)

Until 2026-08-12 the paragraph above also claimed "No Esri tile is cached in bulk or shipped inside the application package." The second half was true; the first half was not.

flutter_map 8.3.0 ships its own disk cache and it is enabled by default: NetworkTileImageProvider._loadImage falls back to BuiltInMapCachingProvider.getOrCreateInstance() whenever a NetworkTileProvider is built without an explicit cachingProvider, and every successfully fetched tile is written to <applicationCacheDirectory>/fm_cache (1 GB ceiling, filename = UUIDv5 of the tile URL). Nobody had turned that off for the satellite layer, so Esri tiles were accumulating on the device. Nothing in our code said "cache" — which is exactly why it went unnoticed.

What is switched off now, by passing cachingProvider: DisabledMapCachingProvider():

What is deliberately left cached — the switch is scoped, not blanket:

• the bundled Sentinel-2 tile is served by AssetTileProvider: no network, no cache, nothing to disable;
• Sentinel-2 fetched over the network is CC BY 4.0, which permits caching, so it keeps its cache;
• the carto / OSM basemaps are unaffected for the same reason.

Known, not yet closed — three further layers still stream Esri through the default (caching) provider. They were out of scope for the change above and are tracked by a test that fails if a fourth one appears (flutter_app/test/onboarding/podklad_cache_test.dart, group Z, case Z4):

• lib/features/map/widgets/weather_basemap_filter.dart — Esri World Hillshade (LandReliefLayer, live on the map)
• lib/features/map/widgets/anchor_zone_draw_screen.dart — Esri World Imagery
• lib/features/settings/screens/area_select_map_screen.dart — Esri Ocean Base

Scope of the verified claim — read this before quoting it. What measurement proves is narrow and deliberately so: the tutorial demo's satellite layer writes nothing to the disk cache. It is not a claim about the app as a whole, and the three layers listed directly above are the reason — one of them (LandReliefLayer) is live on the main map today. An earlier revision of this file ended with the unqualified sentence "no Esri tile reaches the disk cache", which contradicted its own preceding paragraph; that wording is withdrawn.

Within that scope the claim is verified by measurement, not by reading the code: the same test renders the demo's satellite layer against a local server and then inspects the cache directory, with a control case proving that a default NetworkTileProvider does write there.

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Last updated: 2026-08-12