Shotline Diving Wreck Profile
- Name: Unknown 18
- Type: Derrick scow
- Year Built:
- Builder: Unknown
- Dimensions: Approximately 98 ft long × 28 ft beam
- Registered Tonnage:
- Depth at Wreck Site: 10 m / 33 ft
- Location: Thunder Bay scuttled vessel area, Mission Island, Lake Superior
Wreck Location Map
Vessel Type
Derrick scow — a specialized barge equipped with a lifting derrick.
Description
The Unknown 18 is a wooden derrick scow, approximately 98 feet long with a 28-foot beam. It is characterized by its flat-bottomed hull and reinforced hold framing designed to support heavy lifting equipment.
History
Unknown 18 was deliberately scuttled as part of harbor clearance or obsolescence practices in the early to mid-20th century. Its presence in Thunder Bay reflects the industrial heritage and disposal methods of early 20th-century harbor authorities.
Significant Incidents
- Scuttled as part of harbor clearance efforts.
Final Disposition
The vessel is upright and partially buried in sediment. The hull is largely intact below the waterline, while the superstructure is stripped or decayed.
Current Condition & Accessibility
Cold, fresh water has preserved large structural timbers, although the upper structure may be too deteriorated for digital reconstruction.
Resources & Links
[shotline_reference_links slug=”unknown-18-derrick-scow” title=”References & Links”]
Derrick scows like Unknown 18 played critical roles in harbor construction, salvage operations, and marine engineering tasks, offering a rare opportunity to study maritime engineering beyond typical cargo or passenger vessels.
Legacy Notes & Full Historical Record
This section preserves the original unedited Shotline content for this wreck so that no historical detail is lost as we transition to the new logbook format.
Site Identification
- Designation: Unknown 18 (per Thunder Bay dive logs)
- Vessel Type: Derrick scow — a specialized barge equipped with a lifting derrick
- Construction Date: Not determined (n.d.)
- Material: Wood
- Dimensions: Approximately 98 ft long × 28 ft beam
- Builder/Origin: Unknown; no registry, plank stamp, or builder’s plaque visible in site imagery
Wreck Site & Final Disposition
- Location: Thunder Bay scuttled vessel area, Mission Island, Lake Superior
- Depth: Estimated 10–18 m (33–60 ft)
- Disposition: Deliberately scuttled as part of harbor clearance or obsolescence practices in the early–mid 20th century
- Condition: Upright, partially buried in sediment; hull largely intact below waterline, superstructure stripped or decayed
Structural Description & Site Observations
- Hull Form: Flat-bottomed scow with reinforced hold framing to support heavy lifting equipment
- Derrick Evidence: Likely base or hinge pads visible on main deck timbers; framing pattern accounts for crane-bearing stresses
- Hardware and Fasteners: Iron bolts and large-diameter timbers consistent with heavy load capacity
- Preservation: Cold, fresh water has preserved large structural timbers; upper structure may be too deteriorated to reconstruct digitally
Research & Documentation Recommendations
| Objective | Suggested Activity |
|---|---|
| Photogrammetry Mapping | Produce a full 3D model to record hull framing, crane bases, and scow dimensions |
| Structural & Load Analysis | Map reinforcement patterns and framing design to reconstruct derrick usage |
| Wood & Timber Sampling | Take core samples for dating (dendrochronology) and material sourcing |
| Hardware Examination | Document bolt and fastener types for comparative analysis |
| Archive Cross-Reference | Check for derrick scow records in Port Arthur construction logs or harbor equipment fleets |
| Comparative Study of Scow Classes | Compare known derrick scows’ hull forms to categorize built class or fleet affiliation |
Historical & Archaeological Significance
Derrick scows like Unknown 18 played critical roles in harbor construction, salvage operations, and marine engineering tasks. Their presence in Thunder Bay’s scuttling ground reflects both this industrial heritage and the disposal methods of early 20th-century harbor authorities. This vessel offers a rare opportunity to study maritime engineering beyond typical cargo or passenger vessels, emphasizing working craft used in naval logistics and infrastructure development.
unknown-18-derrick-scow 1936-07-21 00:25:00