This section explains, at a high level, how routes and distances are calculated in Port Guide & Distances (the “App”) and the key limitations of these methods. It should be read together with the Terms of Use, Disclaimer and Attribution & Licenses.

1. General Approach

1.1. Routes and distances in the App are generated using proprietary algorithms and data models developed by Marine Solutions SD Group.

1.2. The purpose of these calculations is to provide indicative, educational and planning-support information, not official navigation data.

1.3. All results are based on simplified geometric and geographic assumptions and on non-real-time datasets (e.g., bathymetry, coastlines, EEZ boundaries). They are not equivalent to official ENCs, paper charts or ECDIS outputs.

2. Distance Calculations and Routing Logic

The App uses several main components in its internal routing process:

2.1. Great-Circle Calculations (Oceanic Passages)

• For long, open-ocean segments, the App uses great-circle calculations (shortest path on a sphere) between reference points.
• In simple terms, the route is approximated along the shortest path over a spherical Earth model, not an ellipsoid, and without detailed consideration of local hazards or operational constraints.
• This approach is widely used for indicative distance estimates but does not replace professional voyage planning on official charts.

2.2. Land and Depth Avoidance (Using Bathymetric and Coastline Data)

• The App attempts to avoid land areas and insufficient depths using:
  • global or regional coastline datasets;
  • GEBCO bathymetric grid and other bathymetric sources (see Attribution & Licenses).
• The algorithms apply thresholds and masks to prevent routes from crossing obvious landmasses and very shallow zones on a simplified global scale.
• These models are coarse compared to official hydrographic products and do not capture all local shoals, obstructions, traffic separation schemes, restricted areas, cables, pipelines, military zones, or port-specific restrictions.

2.3. Port Gates and Choke Points

• For many ports and constrained areas, the App uses predefined “gates” and choke points, derived from:
  • general maritime practice;
  • public and open data;
  • proprietary editorial adjustments.
• These gates are used as reference points to:
  • approximate entry/exit points for ports;
  • enforce routing through indicative straits, channels or passage lines.
• These points and lines are schematic and not precise reproductions of official fairways, pilotage routes, leading lines or traffic separation schemes.

2.4. Schematic Route Line (Map Display)

• The route displayed in the App is a schematic polyline drawn on a simplified base map for educational and illustrative purposes only.
• The map projection, coastline detail and symbolisation are generalised.
• The line on the map is not to be used:
  • as a track line on ECDIS;
  • as a replacement for plotted routes on official charts;
  • as proof of safe water, sufficient UKC, or compliance with any navigation rules.

3. Data Sources and Preprocessing

3.1. Underlying data may include (see Attribution & Licenses):

• GEBCO bathymetric data;
• global coastlines and EEZ boundaries;
• selected open data (e.g., OpenStreetMap / OpenSeaMap, Marine Regions);
• public domain port indices and other references;
• proprietary port and route points compiled by Marine Solutions SD Group.

3.2. These datasets are:

• simplified, resampled and transformed for performance and global coverage;
• combined with proprietary logic, weightings and filters to generate indicative distances and path shapes.

3.3. As a result, the final output in the App is an original, derived product, not a direct reproduction of any single underlying dataset.

4. Key Limitations

The methods described above have important limitations. In particular, routes and distances in the App:

• are not based on official nautical charts or real-time data;
• do not include:
  • real-time or forecast weather, currents, tides, waves or ice;
  • traffic separation schemes and detailed routing measures as published by official authorities;
  • up-to-date Notices to Mariners, Local Notices, temporary or preliminary corrections;
  • dynamic restrictions (e.g., draft limits due to siltation, construction works, temporary closures);
• may omit or oversimplify:
  • shoals, reefs, wrecks, obstructions and other hazards;
  • port approach complexities, pilot boarding grounds and anchorage patterns;
  • legal or environmental restrictions (e.g., MPAs, emission control areas).

Therefore, the App:

• provides no guarantee of accuracy, completeness or fitness for any particular purpose;
• is not suitable for navigation, primary or backup;
• is not suitable for safety-critical planning, statutory voyage plans or compliance documentation.

5. User Responsibility

5.1. All distances, routes and ETAs generated by the App are estimates only. They must be independently verified and refined using:

• official ENCs and paper charts;
• up-to-date nautical publications and routing guides;
• company tools, ECDIS and professional judgement;
• instructions from VTS, pilots, Harbour Masters and other authorities.

5.2. By using the App, you acknowledge and agree that:

• you remain solely responsible for navigation, voyage planning and safety;
• any use of the App’s outputs for operational decisions is at your own risk;
• the App is intended as an educational and planning-support tool, not as a primary decision-making system.

6. Updates and Methodology Changes

6.1. We may improve or adjust our algorithms, datasets and internal parameters over time. This may change:

• distances reported between the same ports;
• shapes and positions of schematic routes;
• internal logic for land/depth avoidance and choke points.

6.2. Such changes are not errors but reflect ongoing development and refinement of our models.

6.3. When significant methodological changes are made, we may update this section and the Effective date above.

7. Contact

If you have questions regarding the methodology or limitations of Port Guide & Distances, please contact:

Marine Solutions SD Group
Email: support@msdmarine.com
Website: www.msdmarine.com