Shotline Diving

Connecting You to the Depths of the Great Lakes

Unidentified Thumb Wreck

Explore the well-preserved remains of a mid-19th-century steamship in Michigan’s Thumb Area Bottomland Preserve. A dive site rich in history and marine archaeology.

Shotline Diving Wreck Profile

  • Name: Unidentified Thumb Wreck
  • Type: Wooden propeller steamship
  • Year Built:
  • Builder:
  • Dimensions: Length ~160 ft (48.8 m); Beam ~23 ft (7.0 m); Depth of hold
  • Registered Tonnage:
  • Location: Lake Huron, within Michigan’s Thumb Area Bottomland Preserve
  • Coordinates: Undisclosed
  • Official Number: Not documented
  • Original Owners: Not yet identified

Wreck Location Map

Vessel Type

The Unidentified Thumb Wreck is classified as a wooden propeller steamship, featuring a single-expansion engine and a haystack boiler with a feedwater pre-heater.

Description

The wreck features a main deck and intact hull; however, the fantail is broken and detached. Machinery includes a haystack-style boiler, feedwater pre-heater, and a single-expansion engine closely matching those on the 19th-century propeller steamer Indiana (now part of the Smithsonian collection). The propeller is missing, and the aft deck structure appears disarticulated, with propeller-shaft hanger-bearing rods visible. On-site artifacts include an anchor windlass with rocker arm (likely operated from forecastle or spar deck), anchors lying on deck, mast remnants, capstan, bits, and two hand-operated cargo winches on the port side, along with scattered hand carts. The sides of the hull lie adjacent to the main hull on the lakebed.

History

  • Operational Profile & Machinery Origin: Based on engine and boiler design, this vessel likely dates from the mid-1800s. The machinery’s similarity to that of Indiana strengthens this estimate.
  • Ownership Chain & Registry: Not yet identified; no registry or official number currently associated with the wreck.
  • Final Voyage & Incident: Insufficient data exists to reconstruct the final voyage or cause of loss. The missing propeller may hint at salvage activity, but this remains speculative without confirmation.

Significant Incidents

  • Cause of Loss: Undetermined—mid-19th-century steamship loss suspected, but no documented cause.
  • Wreck Condition: Largely intact—but with broken fantail, missing propeller, and scattered structural debris including displaced sides.

Final Disposition

The wreck lies within Michigan’s Thumb Area Bottomland Preserve, where disturbance or removal of artifacts is strictly prohibited under state law.

Current Condition & Accessibility

  • Access Type: Likely Boat—typical for Thumb Area wrecks (shore access is limited).
  • Entry Point: From nearest marina or launch at Port Austin or Harbor Beach.
  • Conditions: Visibility can vary, often modest; Lake Huron’s clarity is seasonal. Depth is unspecified but likely beyond recreational limits without a known site depth. Diving may require technical certification, given typical regional depth profiles (many wrecks beyond 100 ft / 30 m).
  • Depth Range: Unknown—further survey required.
  • Emergency Contacts & Permits: Use local NOAA rescue or Michigan DNR dive guidelines. No permits are generally issued—wreck is protected, so only non-intrusive documentation allowed.
  • Local Dive Support: Charter services available via Port Austin or Alpena dive operations.

Resources & Links

The Unidentified Thumb Wreck offers a rare, well-preserved mid-19th-century steam-era vessel structure with intact machinery and hull features. It remains officially unidentified; further archival research may eventually reveal its identity. The site is responsibly documented using modern underwater photogrammetry and lies within a protected preserve ensuring its long-term preservation.