{
  "title": "Bay City",
  "era": "Original brig-rigged career, 1857–1869",
  "version": "1.1",
  "modelStatus": "Interpretive reconstruction; no original lines plan recovered",
  "detailLevel": "full",
  "units": "metres",
  "axes": {
    "up": "+Y",
    "bow": "-X",
    "starboard": "+Z"
  },
  "historicalDimensions": {
    "lengthFeet": 146,
    "beamFeet": 29,
    "depthOfHoldFeet": null,
    "beamInferred": false,
    "holdDepthUnknown": true,
    "lengthBasis": "146 ft surviving1902 wreck length used as an approximate display baseline, not verified original brig length"
  },
  "geometryReference": {
    "hullBowX": -22.250400000000003,
    "hullSternX": 22.250400000000003,
    "deckY": 3.65,
    "waterlineY": 2.7,
    "waterlineIsInferred": true
  },
  "bounds": {
    "min": [
      -28.946309973104356,
      0.0050000000000000044,
      -9.415984
    ],
    "max": [
      22.31830723962261,
      40.1524233733251,
      9.415984
    ]
  },
  "triangleCount": 75284,
  "trianglesByGroup": {
    "hull": 12668,
    "bulwarks": 9380,
    "fittings": 2868,
    "deck": 6856,
    "propulsion": 52,
    "anchors": 636,
    "deckhouses": 936,
    "cargo_hatches": 120,
    "hatch_covers": 288,
    "spars": 7456,
    "standing_rigging": 2316,
    "sails": 25364,
    "running_rigging": 4032,
    "ship_boat": 1816,
    "steering": 412,
    "skylights": 84
  },
  "drawCalls": 55,
  "mastCount": 2,
  "supportsSails": true,
  "visibilityNodes": {
    "sails": "sails"
  },
  "deployedSailCount": 9,
  "inferredFeatures": [
    "The original brig’s two square-rigged masts are supported as a configuration, while their heights, yard spans, sail areas and stations are period-proportion interpretations.",
    "The revised main mast is about 120 ft above deck and the lower yards about twice the beam; these are comparative rig proportions, not measured Bay City spars.",
    "Using 146 ft as the display hull baseline is a qualified proxy from surviving wreck length. Cabin, hatches, paint and concealed hull remain inferred."
  ],
  "configurationCaveat": "Shown in the original brig rig, 1857–1869; after the 1869 fire she was cut down and later wrecked as a two-masted schooner barge. Rig dimensions are period inferences. The 146 ft geometry baseline is surviving wreck length, not an established original complete length.",
  "revisedDate": "2026-09-08",
  "revisionNote": "Corrected the September 2026 audit findings and distinguished documentary evidence, interpretation and unresolved conflicts.",
  "documentedFeatures": [
    "NOAA’s vessel record identifies a wooden two-masted schooner barge built in 1857 and lost in 1902. The 146 ft figure describes the wreck, not a verified original brig hull length. [NOAA](https://thunderbay.noaa.gov/shipwrecks/bay-city.html).",
    "Visit Alpena describes Bay City as originally brig-rigged and cut down after burning at Detroit in 1869. It also records stern loss from the later wreck. [Visit Alpena](https://www.visitalpena.com/blog-your-guide-to-shallow-shipwreck-exploration-in-alpena/)."
  ],
  "sources": [
    {
      "title": "NOAA Bay City",
      "url": "https://thunderbay.noaa.gov/shipwrecks/bay-city.html",
      "use": "See the cited evidence and uncertainty sections in the research notes."
    },
    {
      "title": "Visit Alpena historical account",
      "url": "https://www.visitalpena.com/blog-your-guide-to-shallow-shipwreck-exploration-in-alpena/",
      "use": "See the cited evidence and uncertainty sections in the research notes."
    }
  ]
}