Evidence
8 evidence entries recorded; each entry has a stable permalink (#ev-1 … #ev-8).
-
[1]Department of the Navy, NAVSHIPS 18-1-11, Naval Vessel Register (1 January 1949), service craft, printed p. 236; scanned Navy original hosted by Generalstaff.org [other_primary]
- Locator
- Printed p. 236, YTB-496 CHAHAO row (PDF p. 237)
- Finding type
- vessel_history
- Finding
- The Department of the Navy's Naval Vessel Register lists CHAHAO as YTB-496 and records vessel status ACT (status code 1) in the 1 January 1949 service-craft list.
- Verification
- verified
- Role
- supporting
- Documentation level
- ship_specific
- Accessed
- 2026-09-24
- Limitations
- This is a service-status entry, not a construction record or material inventory. It does not identify propulsion, builder, complement, asbestos, or any individual exposure.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-01
-
[2]Occupational Safety and Health Administration, Occupational Exposure to Asbestos, 59 Fed. Reg. 40964 (10 August 1994), shipbuilding and repair preamble [federal_register]
- Locator
- Shipbuilding and repairing—historical contact with asbestos in shipyard work, around lines 1749-1755 in OSHA HTML
- Finding type
- asbestos_application
- Finding
- OSHA's 1994 asbestos rulemaking describes extensive asbestos use on American ships from the early 1940s through late 1970s, including insulation and interior materials. This establishes only era-wide research context for a tug recorded active in 1949.
- Verification
- verified
- Role
- supporting
- Documentation level
- class_or_era
- Accessed
- 2026-09-24
- Limitations
- OSHA discusses American ships generally, not the YTB-496 design or Chahao. No listed product may be attributed to this hull and no exposure is established.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-02
-
[3]National Archives, Researching Asbestos aboard US Naval Vessels up through 1961, Cartographic Branch guidance [other_primary]
- Locator
- Cartographic Branch section, RG 19 Hull Series and Microfilm; S39, S48, S103
- Finding type
- historical_record
- Finding
- NARA identifies Navy ship engineering drawings in RG 19, especially filing code S39 for insulation and lagging, S48 for piping, and S103 for general plans, as the next records to inspect for hull-specific asbestos research.
- Verification
- verified
- Role
- archival_lead
- Documentation level
- context_only
- Accessed
- 2026-09-24
- Limitations
- This is repository guidance, not a located Chahao drawing. NARA warns S39 and S48 paper drawings are relatively rare; the ship's material specifications remain unverified.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-03
-
[4]Naval Sea Systems Command, Ship History (28 June 2011), indexed p. 105 [other_primary]
- Locator
- Indexed p. 105, YTM 0496 CHAHAO row; search-index excerpt only
- Finding type
- vessel_history
- Finding
- NAVSEA's indexed Ship History table lists 'YTM 0496 | CHAHAO' with final disposition 'Sunk 6/17/96'; the removal-date field is blank.
- Verification
- partial
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-09-24
- Limitations
- The official PDF returned HTTP 403 on direct retrieval. The indexed excerpt confirms the wording but the full page was not inspected. It does not specify sinking location, cause, target use, removal date, or asbestos condition.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-04
-
[5]Batch 9418 search ledger and research report, 24 September 2026 [other_primary]
- Locator
- search_ledger rows sl-uss-chahao-ytb496-01 through -12; BATCH-9418-REPORT.md
- Finding type
- historical_record
- Finding
- No ship-specific asbestos survey, construction specification, or abatement record was located in the official public sources searched. Completed exact-name CourtListener opinion and docket searches returned zero hits; hull-number litigation searches were blocked by the shared pacing limiter. Hull-specific asbestos and litigation status therefore remain unknown beyond those completed searches.
- Verification
- partial
- Role
- negative_finding
- Documentation level
- ship_specific
- Accessed
- 2026-09-24
- Limitations
- A negative search result is not proof that asbestos was absent or nobody was exposed. CourtListener hull-number searches did not run because the fleet-wide limiter refused requests before HTTP; this row does not establish an absence of litigation under those identifiers.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-05
-
[6]NOAA Maritime Heritage Program, The Unseen Landscape: Inventory and Assessment of Submerged Cultural Resources in Hawai‘i, BOEM OCS Study 2017-021 (2017) [other_primary]
- Locator
- Appendix 4, Summary Inventory List, printed p. 164, record 295; section 2.8.1, printed pp. 10–11, category 4 definition
- Finding type
- historical_record
- Finding
- A 2017 BOEM report prepared by NOAA lists “Chahao, USS ex” as a tugboat lost in 1996, vicinity Oahu, Hawai‘i. It rates location accuracy category 4 (poor) and lists no site survey.
- Verification
- partial
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-09-24
- Limitations
- The inventory names Chahao but gives no hull number; linkage to YTB/YTM-496 is supported by the matching vessel name, tug type, and 1996 NAVSEA disposition, and is still an inference. Category 4 means the location is unreliable or vague; no exact coordinates, field confirmation, or asbestos condition are established.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-06
-
[7]U.S. Environmental Protection Agency, Technical Development Document: Proposed Phase I Uniform National Discharge Standards for Vessels of the Armed Forces, glossary [other_primary]
- Locator
- Glossary and Abbreviations, GL-11, YTB and YTM entries
- Finding type
- historical_record
- Finding
- The federal vessel-code glossary defines YTB as “large harbor tug” and YTM as “medium harbor tug”; those meanings decode the designations shown in the Navy records.
- Verification
- verified
- Role
- context
- Documentation level
- context_only
- Accessed
- 2026-09-24
- Limitations
- This decodes hull classifications; it does not document Chahao design details, propulsion, dimensions, or asbestos materials.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-07
-
[8]National Archives, Ship Plan Index, CHAHAO entry; compared with Department of the Navy, 1949 Naval Vessel Register, printed p. 236 [other_primary]
- Locator
- Ship Plan Index, CHAHAO result, RG 19 Hull Series, catalog 153716510; register printed p. 236
- Finding type
- historical_record
- Finding
- NARA’s public Ship Plan Index returns a “CHAHAO / YTB-215” row. That hull identifier conflicts with the Navy’s 1949 register entry “YTB-496 CHAHAO,” so no drawing from the index row is attributed to this vessel pending archival clarification.
- Verification
- partial
- Role
- correction
- Documentation level
- ship_specific
- Accessed
- 2026-09-24
- Limitations
- The NARA index entry was visible in official search results, but the full index page was not retrievable in this session. It may be a transcription error or refer to a different drawing; its catalog record and any associated plan have not been inspected. It establishes no asbestos condition.
- Atlas source
- true
- Evidence ID
- ev-uss-chahao-ytb496-08