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Ahoi Captains, Here is a quick guide for importing you own created watercraft into the sim. I will improve and expand the docs for importing over the dev time. You can you the small car ferry in the Mods/Boats folder as a template. Structure tree of imported models. Mods/ └── Boats/ └── MyFishingBoat/ ├── boat.json ├── ship.fbx ├── preview.png ├── Textures/ │ ├── hull_basecolor.png │ ├── hull_normal.png │ └── hull_roughness.png └── Sounds/ ├── engine_idle.wav ├── engine_running.wav └── horn.wav Ship Setup — imported ships only # Open and edit 1. Open ship selection, choose a custom ship and press **Ship Setup**. 2. Right-drag to orbit; middle-drag to pan; wheel to zoom. Click the preview for keyboard focus, then use W/A/S/D and Q/E to move the view. Shift increases the movement step. 3. Select a point in the left list or click its marker. Drag an axis (red X, green Y, blue Z), or commit a numerical coordinate on the right with Enter or by leaving the field. 4. **Preview bridge** looks from the configured camera. **Use view as bridge** copies the current preview camera position, rotation and FOV to that point. **Frame ship** returns to orbit. 5. **Save JSON** writes setup to this package's `boat.json`. It preserves unrelated top-level fields, including the existing physics tuning. Known setup objects/arrays are rewritten. Changes apply on the next voyage, not to a boat already running in the world. 6. **Close / discard unsaved** discards unsaved configuration changes. It does not undo earlier saves. The preview has no boat simulation or collision and is destroyed on close. No Blueprint boat assets or their buoyancy settings are changed. It is currently a standalone/singleplayer authoring tool. The source FBX is not changed by this tool. Before a save, the previous JSON is copied to `Saved/ShipSetupBackups/<id>/boat-<unique-id>.json`. If the manifest changed since opening, the save is rejected: close and reopen Ship Setup. Read-only installations cannot be edited until the mod directory is writable. Backups are outside the Mods directory and therefore are not automatically included in a new package. # Propellers and rudders: one FBX, separate objects Recommended authoring convention: - Hull/superstructure: ordinary static objects. - `Prop1`, optionally `Prop2`: individually selectable propeller mesh objects. - `Ruder1`, optionally `Ruder2`: individually selectable rudder mesh objects. Export the objects **together in the main ship FBX**. Do not combine them into one hull mesh. Each name must be unique. Apply export scale/orientation consistently and triangulate. All vertices should remain in the ship's assembled positions. Empty helper nodes are not visible propeller/rudder meshes. The editor dropdown can map other object names; names are matched case-insensitively. Missing, ambiguous or already-used names skip animation rather than preventing the boat from loading. Select **None** when no visual model is available. The physical propulsion/rudder points still work. There is no requirement to supply these meshes immediately. The current ferry can use its existing FBX until the propeller/rudder objects are modelled. Separate extra FBX files are not imported by this version. They can be supported later, but would also need explicit transforms, scale and material paths. Each part has two points: - **Force**: where the existing boat physics applies propulsion/rudder forces. - **Pivot**: the rotation centre of the visible object. It need not equal the force point. `axis` and `direction` control **cosmetic animation**, not an azimuthing thrust direction. The axis is in boat coordinates, nonzero and normalised on save; +X is typical for shafts, +Z for rudders. Use +1 or -1 for direction. **Toggle animation** tests the pivot and direction without running physics. During a voyage, propellers follow engine RPM/drive direction and rudders follow steering input. The native propeller animation speed scale remains 0.2. Two engines split `thrustKN` equally; adding the second engine does not double the configured total thrust. The normal two-engine UI is reused. # Mooring and fenders **+ Mooring point** creates a station that works with the existing O / Ctrl+O mooring interface. Set position, label, rope diameter, maximum length and breaking load. Up to 32 stations are supported. **+ Fender** adds a standard small rubber-fender representation (an elongated sphere), plus a separate **rope top** marker. Position the centre alongside the hull and the rope top on the rail/attachment. The wire outline in the preview shows the configured size. Port/starboard chooses the control group; changing the side button also sets yaw to face outboard. Local +X must face away from the hull, +Z up. The runtime component reuses the existing deployment, contact and cosmetic pendulum logic. Its visible rope ends at the fixed ship attachment and it adds no separate rigid-body mass. Up to 32 fenders. Custom fender mesh files and large quay-fender authoring are not part of this ship-setup extension. # Sounds and preview images Select **Engine sound** or **Horn sound** to edit sound filenames and attenuation. Files are relative to the boat folder. Use forward slashes, for example `Sounds/engine.wav`; absolute paths, `..` and backslashes are rejected. Empty fields are allowed. A missing/unsupported WAV is skipped with a warning. - Supported audio: uncompressed PCM16 WAV, mono/stereo, 8–96 kHz, at most 16 MiB and 120 seconds each. - Prefer **mono** for spatial localisation. Supply engine start, seamless running loop, engine stop and horn as separate files. The two engines have independent playback cursors but share the configured engine sound position in this version. No sound assets are supplied/generated by the code. - Attenuation inner radius and falloff are in centimetres; volume is 0–2. - Supported selection image: PNG, at most 2048 × 2048 and 8 MiB. When the `preview` field is missing or empty, `preview.png` beside `boat.json` is used automatically. Explicit filenames take priority; an invalid/missing explicitly selected image does not silently fall back to another file. Reopen ship selection after copying an image into the package folder. - **Create preview PNG** captures the current ship-only view without markers to a unique new PNG in the package. Then press **Save JSON** to assign it. Existing images are not overwritten. The generated PNG remains on disk even if you close without saving the configuration; remove unused captures manually. # JSON fields (optional extension to schemaVersion 1) Existing schema-1 manifests still load with one physical propeller and rudder and their legacy points. Retain the required legacy `cameraCm`, `propellerCm`, `rudderCm` fields. The editor keeps the latter two in sync with the first array entries. New fields can be added to the existing object; this fragment is not a complete manifest and its coordinates are examples, not calibrated positions for the ferry Positions/sizes are boat-local centimetres (+X bow, +Y starboard, +Z up), **after** the presentation model's scale/offset/rotation. Rotation arrays are pitch, yaw, roll in degrees. These setup settings do not automatically compute hull collision, displacement or stability. Keep the existing tuned values. # Imported-ship handling settings Ship Setup now has four English-language sections: **Performance**, **Rudder**, **Heeling**, and **Resistance**. These expose the existing native BoatPawn controls, not a new physics model or automatic copying from a Blueprint boat. Save with **Save JSON**, then start a new voyage. Blueprint boats and the existing imported-ship buoyancy coefficients are unchanged. - Performance: total/per-shaft thrust, reverse thrust, RPM response, thrust exponent, optional low-speed boost, engine-start immersion requirement and speed limiting. - Rudder: angle, actuator speed, lift/force limits, propeller wash and each rudder's physical area. Length and height are full centimetre dimensions; they do not resize the visible mesh. - Heeling: None, Inward or Outward turn heel, strength, maximum angle, response/return times and minimum speed. This is turn-induced heel, not wave damping. - Resistance: lateral grip, three-point resistance and its yaw contribution/weights, plus linear/angular damping. Angular damping affects all rotation, including roll and pitch. An optional `handling` object uses the exact C++ property names shown below each control. Only edited overrides are stored. **Default** removes that override and restores the native default; per-shaft thrust instead falls back to an equal share of root `thrustKN`. Root `thrustKN`, `linearDamping` and `angularDamping` are saved from their own controls. Second-shaft/second-rudder settings require two corresponding attachment entries. Native force values are Unreal force units: **1 kN = 100,000 UE units**. Example fragment (illustrative values):

Hey Captains, Weekly update for the sim. Added local harbor zone and low-cost buoyancy for swimming scenery objects like buoys and fenders.

Testing NVidias Waveworks 2 water engine in Across the Seas. First test with local wakes as boat wakes. Looks nice in motion and Waveworks gives a little nice performance boost.

Alpha Version 0.0.17 - Mooring and anchor system is now live - Harbor and boat fenders added - FPS view added Key "3" - Freelock camera added Key "4" - Improved tile chunking for patching - Added user importing watercrafts - GPS window key "G" added - Added moveable parts for watercraft - Watercrafts can now be controlled with 3d steering wheels and throttles - Orbitcam logic reworked - Basic weather menu added Key "T" - Custom buoyancy added (C++ core) - Added low-poly terrain from Calais up to Elbe approach - Increased radar range to 16nm

Hello Serkan, thank you very much for your kind of words. I`m glad you like it so far.

Hello Marko, I had the chance to try Across the Seas Launcher 1.0.10, and I’m quite impressed with it, especially considering that it’s still in alpha. The sea and weather physics already feel very realistic and give a great sense of being on the water. It’s clear that there is a lot of potential here, and I’m looking forward to seeing how the simulator develops over time. Keep up the great work, and best of luck with the project!

The wait ist over, I have released the new alpha version of Across the Seas - Maritme Simulation. You can read the release notes here.

Hello Captains, Download Page for the Launcher Welcome to the Unreal Engine based version of Across the Seas. The free alpha/beta version is now ready to download via the new custom launcher system. What comes with the first release. You can test sail 3 types of boats. One small fishing boat, a small two-shafted yacht and as an larger ship the Agile. More ships will follow in the next couple of weeks. As a first scenery, you can sail in the Dover Calais area. Hower Dover is not finished yet. I use Dover as a test object for the physics of the floating point precision. I have also added low-poly terrain up to the Elbe approach. So you can sail from Calais along to the Dutch coast to the Elbe. But for now, it's terrain only, no trees, building or other objects are placed. The water floor with depth is ready but currently not visible. It's only visible at the start location screen, minimap and the sonar. So anchoring is also currently only possible in the Dover Calais area. I'm working on that, to allow anchoring at the low-poly terrain also. Another limitation is, there are no boat wakes yet. Key's for the sim: 1 - Bridge view 2 - Orbit camera 3 - First persion view 4 - Freefly camera T - Weather and time window O - Mooring panel CTRL + O - Mooring and anchoring window M - Minimap G - GPS window E - Sonar and echosounder L (held) - Lights panel L (pressed) - Cycle through lighting states CTRL + C - Hide and unhide the ingame UI Space - Throttle to zero Custom boat import is also implemented. I will upload an description shortly. So you can test your own watercrafts in Across the Seas.

Working on a new terrain system, for adding modding capability to the sim. I have added low poly terrain with a depth map from the Dover Calais area up to the Elbe approach. Now you can also spawn elsewhere on the water surface, as long there is sufficient water depth. Also implemented Openseamap.org as the new minimap system. So no more need to repaint the minimap for every scenery. New start selection screen. With scenery based start points and also the capability of selecting free starting points. Low-poly terrain of Helgoland. Openseamap.org based minimap system.

New milestone for Across the Seas. It's now possible to add your own watercrafts to the sim. You need to export your watercraft as an FBX file. For editing most of the visual things like propellers, rudders and mooring points, I created an ingame editor. The config files are saved as json files. In the json file you can also setup manually the buoyancy and a few other parameters of the boat physics to match the behavior to your liking. I will create an documentation for the needed folder structure of your model. I will ship this feature also with the release of the free alpha and beta version. Ingame Editor test. Loaded custom watercraft into the sim.

Playing around with the mooring system. Also added working fenders to the scenery and smaller ones for the watercrafts. You can deploy and stow the boat fender.

Mooring and anchor logic is done. You can moore the ship as long as an bollard is available at your location. That includes the possibility for towing other watercrafts. Also added a complete anchor system with multiple anchors support.

This weeks development update. The buoyancy physics is now completely rewritten and is now fully custom made. The Agile is the first medium sized ship and ready for sea trails. Also the whole steering and rudder logic is completely overhauled. Thrusters are also fully working. Now you can also steer the watercrafts with mouse from the 3d bridge. You can steer the boats with Joysticks (needs only to set axes for throttles and rudder), via the UI and from the bridge view. Also added moveable parts to the watercrafts, like the propellers, rudder, radars etc. First implementation of weather and time is ready for the upcoming alpha. You can set your prefered time of day and choose your weather preset.

Boat and map selection screens with different starting points are now implemented. 2d UI panel radar Echo sounder with basic sonar instrument.

Hey Captains, In preparation for the release of the Unreal Engine based version of Across the Seas. I have created my own custom launcher system which is based of LaunchBoost.io This allows to updates of particularly small files during the further development of the sim. Regards, Marko

Ahoi Captains, Across the Seas is not dead. After an long time without any news about the sim and it's current state, I'm back with good news. After the first internal test version in UE 5 with an mostly off Blueprints based version, I wasn't very happy with the result and the state of AtS. So I decided to take an fundamental step and so I started from scratch with UE and a C++ core code of the sim. So after getting a lot of headaches and pain, now the physics and the watercraft controller are full written in C++. Also the base of the GUI is completely C++ code. Across the Seas will now be developed in UE 5.8. This version brings a lot of improvements like a good implementation of 64bit floating point precision (with Unreal's Large World Coordinates) and mesh terrains and other UE features like Metahuman, Metasound and Megalights. I'm quite happy now with the way the simulator looks and feel. Most parts of the water and weather systems are done. With the further development of the sim, I will also make improvements and adding more features to the watercraft / player controller and also to improve the GUI. So the release of the first UE based prototyp, I have decided to give it a go at the late Q3 or early Q4 of 2026 release. Like the old Unity version, I will update the alpha/beta version during the development period. Here is also an Trello Board with the status of the sim. Main features of the Unreal Engine version: - C++ code base for physics, watercraft controller and the GUI - Support for very large sceneries - Native DLSS 4.5 and Nvidia's Frame Gen integration (FSR integration Work in Progress) Stay tuned for more news and the first new version of Across the Seas. Regards Marko