# EnvShip-Voyage — Data Card (voyage_v1)

**Task.** Long-term vessel trajectory **imputation** (primary) and **prediction** (secondary) from AIS.
**Region.** DMA (Danish waters), bbox {'lat_min': 53.5, 'lat_max': 59.0, 'lon_min': 7.5, 'lon_max': 14.0}. **Ship classes.** ['cargo', 'tanker'].
**Sampling.** native 1 min; flagship view 5 min.
**Windows.** [12, 6] h, stride 6 h.
**Masks.** continuous curriculum + MCAR + real gaps (frozen bank, seed 1220).
**Splits.** vessel-disjoint MMSI-hash [0.7, 0.1, 0.2] + temporal pretrain pool.
**Provenance.** DMA AIS (['2026-01', '2026-02', '2026-03', '2026-04', '2026-05', '2026-06']); reuse of EnvShip stages 01-04; see PLAN + RESEARCH_NOTES.

## Summary statistics
```json
{
  "n_samples": 179131,
  "splits": {
    "train": 118292,
    "test": 40903,
    "val": 19936
  },
  "window_len_h": {
    "6": 100278,
    "12": 78853
  },
  "difficulty": {
    "medium": 82255,
    "easy": 63205,
    "hard": 33671
  },
  "ship_class": {
    "cargo": 121340,
    "tanker": 57791
  },
  "n_vessels": 5804
}
```

## Comparison
| | KDD'24 imputation | EnvShip (short-term) | **EnvShip-Voyage** |
|---|---|---|---|
| horizon | 12 h | 10-60 min | 12 h / 6 h |
| sampling | 5 min | 20 s | 1 min native / 5 min flagship |
| task | imputation | prediction | imputation + prediction |
| masks | cont 6/8/10 h | - | cont 1-10 h + MCAR + real gaps |
| environment | none | anchor raster | streaming basemap + fairway network |
| region prior | none | coastline | fairway / traffic network (first-class) |

## Intended use / limits
Research benchmark for maritime trajectory imputation and long-horizon prediction. Not for navigation
or vessel re-identification. MMSI is pseudonymised. Derived from public AIS + OSM + ETOPO 2022 bathymetry.