Evidence
10 evidence entries recorded; each entry has a stable permalink (#ev-1 … #ev-10).
-
[1]research packet 1068-packet.md (3 sources cited) [other_primary]
- Finding type
- vessel_history
- Finding
- Identity packet verdict: VERIFIED
- Verification
- verified
- Role
- supporting
- Documentation level
- ship_specific
- Evidence ID
- uss-yms-423-yms423-pkt-1068-packet-md
-
[2]NavSource Online: Mine Warfare Vessel Photo Archive, YMS-423 page (compiled vessel record) [other_primary]
- Locator
- Vessel specifications block and fate paragraph
- Finding type
- vessel_history
- Finding
- Compiled vessel record for this hull: YMS-1 class auxiliary motor minesweeper; laid down 27 December 1943 by Astoria Marine Construction Co., Astoria, OR; launched 5 August 1944; completed 25 October 1944; struck from the Navy Register 25 February 1947; transferred to the War Shipping Administration 26 December 1947; sold to South Korea in 1948 and renamed ROKS Kaya San (YMS 511); sunk in 1949. Class specifications: 270 t; 136 ft x 24 ft 6 in x 8 ft; 15 kt; complement 32; one 3"/50 dual-purpose mount, two 20 mm mounts, two depth-charge projectors; two 880bhp General Motors 8-268A diesel engines, Snow and Knobstedt single-reduction gear, two shafts. Call sign Nan-Queen-George-Oboe. The page states no DANFS history exists for YMS-423.
- Verification
- verified
- Role
- supporting
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1943-1949
- Population
- Astoria Marine Construction trades 1943-44; wartime crew (design complement 32)
- Limitations
- NavSource is a secondary compiled record (volunteer-maintained photo archive of official data), not a primary document - dates and fates corroborated where possible against uboat.net, Navpedia, and the NAVPERS awards tables, but no primary transfer/disposal instrument was located. 'Completed' wording differs from uboat.net's 'commissioned' (see ev-08). Establishes identity and milestones only - contains no materials or asbestos information.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-01
-
[3]NHHC Online Reading Room, 'United States Pacific Fleet Organization, 1 May 1945' (primary source document; also transcribed at HyperWar/ibiblio.org USN/OOB/PacFleet/Org-450501) [nhhc_danfs]
- Locator
- MINECRAFT, PACIFIC FLEET > Mine Squadron Twenty YMS table, row 'YMS 423'
- Finding type
- vessel_history
- Finding
- The official Pacific Fleet organization document of 1 May 1945 lists 'YMS 423' in the motor-minesweeper block under MINECRAFT, PACIFIC FLEET (Commander Minecraft, Pacific Fleet, R. Adm. A. Sharp), within the Mine Squadron TWENTY grouping (Commander Mine Squadron Twenty, Capt. R. A. Larkin). The entry carries footnote marker (1); the commanding-officer column is blank.
- Verification
- verified
- Role
- supporting
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1945-05-01
- Population
- Pacific Fleet minecraft crew, May 1945
- Limitations
- An organizational listing, not an operational record - it establishes fleet assignment on 1 May 1945 but gives no station, operations, condition, or materials data. The meaning of footnote marker (1) is not legible in the online transcription and is not interpreted here.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-02
-
[4]NAVPERS 15,790, Navy and Marine Corps Awards Manual (rev. 1953), Part IV - Asiatic-Pacific Area ship-eligibility list and operation tables; Navy Occupation Service Medal ship list (Awards-IV-17); HyperWar verbatim transcription [other_primary]
- Locator
- Awards-IV-16: 'YMS 423:' entry in the Asiatic-Pacific ship list; P34 and P207 operation-name tables. Awards-IV-17: Navy Occupation Service Medal table, 'YMS 423 ... 2 Sep 45 - 24 Feb 46 ... A'
- Finding type
- vessel_history
- Finding
- The official campaign-participation tables credit this hull with: P34-1, Assault and occupation of Okinawa Gunto, 25 March 1945 - 30 June 1945; P207-9, Kobe (Honshu Area) post-surrender minesweeping, 5 December 1945 - '29 Feb 45' as printed (impossible date - 1945 was not a leap year and the P207-9 operation window ran 28 Nov 1945 - 9 Mar 1946; read as 29 February 1946, see ev-08); P207-10, Kure-Hiroshima (Honshu Area) minesweeping, 19 January 1946 - 19 February 1946. The Navy Occupation Service Medal ship list (Part IV, section 17+) credits YMS 423 for Asiatic-Pacific ('A') occupation service 2 September 1945 - 24 February 1946.
- Verification
- verified
- Role
- supporting
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1945-03-25 to 1946-02-24
- Population
- Wartime and occupation-era crew (complement ~32)
- Limitations
- Award-eligibility credit, not an operational log - establishes qualifying presence in each operation area during the credited windows, not day-by-day movements. The printed '29 Feb 45' end date is a manifest typographical error; no other hull's P207-9 dates were relied on to correct it (window constraint only). Transcription verified at HyperWar; the manual itself is the underlying official document.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-03
-
[5]National Archives and Records Administration, Special List 44: List of Logbooks of U.S. Navy Ships, Stations, and Miscellaneous Units, 1801-1947 (ship-number list) [other_primary]
- Locator
- sl-44-ship-number.pdf, p.121, 'YMS-423 10/25/1944 12/31/1945'
- Finding type
- historical_record
- Finding
- Special List 44 inventories U.S. Navy deck logs for YMS-423 covering 25 October 1944 - 31 December 1945 (entry 'YMS-423 | 10/25/1944 | 12/31/1945', PDF page 121). The holdings sit in Records of the Bureau of Naval Personnel, Record Group 24, Entry 118 (NAID 581208). The log coverage start coincides with the vessel's completion/entry-into-service date.
- Verification
- verified
- Role
- archival_lead
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1944-10-25 to 1945-12-31 (log coverage); inventory consulted 2026-10-04
- Limitations
- Inventory entry proves the logs exist in NARA custody and their coverage window - it does not expose their contents. Whether the YMS-423 logs are digitized in the National Archives Catalog was not confirmed this session (catalog is JS-gated for scripted access; see search ledger). Log pull is the primary ship-specific avenue for detailed operations, availability/yard periods, and any materials notes.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-04
-
[6]Navpedia, 'GEUMGANGSAN coastal minesweepers (1942-1944/1947-1956)' - Republic of Korea Navy table (corroboration for NavSource fate data) [other_primary]
- Locator
- Geumgangsan-class table row '가야산 [Gayasan] (ex-YMS423) | 511'
- Finding type
- vessel_history
- Finding
- Navpedia's ROKN table lists 'Gayasan' (ex-YMS423), pennant 511, builder Astoria Marine, laid down 12/1943, launched 5.8.1944, completed 10.1944, transferred to the Republic of Korea 1948, fate 'sunk 1949' - matching NavSource's ROKS Kaya San (YMS-511) entry for this hull.
- Verification
- partial
- Role
- supporting
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1948-1949
- Population
- Republic of Korea Navy crew, 1948-49
- Limitations
- Secondary reference compilation agreeing with NavSource; neither cites a primary transfer document or loss report, and no source located gives the sinking's cause, date, or location. Korean-language ROKN records were not searched; romanization differs across sources (Kaya San / Gayasan).
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-05
-
[7]NavSource Online: Auxiliary Motor Minesweeper (YMS) Photo Index - class description and specifications [other_primary]
- Locator
- NavSource YMS index class narrative; specifications repeated on the YMS-423 page (19423.htm)
- Finding type
- asbestos_application
- Finding
- Class context for the asbestos question: the YMS type was a wooden-hulled motor minesweeper built at 35 U.S. yacht yards; the class carried two General Motors 8-268A diesel engines - no boilers and no steam plant. Period shipbuilding practice used asbestos in gaskets, machinery and exhaust insulation, electrical insulation, and friction materials, but no class-level materials list or industrial-hygiene document for the YMS type was located; on a wood/diesel craft those applications are materially narrower than the boiler-and-steam-pipe insulation scope of larger vessels.
- Verification
- inferred
- Role
- context
- Documentation level
- class_or_era
- Accessed
- 2026-10-04
- Study period
- 1943-1944 (construction); 1944-1949 (service)
- Population
- Astoria Marine construction trades 1943-44; embarked crew ~32
- Limitations
- Class/era inference only - no document located states that asbestos products were installed in the YMS-1 class or this hull. The absence of a steam plant removes the highest-volume asbestos pathway (boiler/turbine lagging) but says nothing about gaskets, wiring, or friction products; presence aboard this hull is neither established nor excluded.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-06
-
[8]U.S. EPA Superfund site profile, Astoria Marine Construction Company (CERCLIS OR0002392793) + ATSDR/Oregon EHAP Health Consultation, 'Astoria Marine Construction Company' (August 2016) [other_primary]
- Locator
- EPA site profile (cumulis.epa.gov, site 1002059); Oregon.gov ATSDR/EHAP Health Consultation PDF, 'Astoria Marine Construction Company HC FINAL_08-12-2016.pdf' (full-text search: no 'asbestos' occurrences)
- Finding type
- environmental_record
- Finding
- The builder yard is a documented contaminated site: the 8-acre AMCCO property on the Lewis and Clark River operated as a marine shipyard from 1924, building wooden boats except for WWII and Korean-war military work including minesweepers; EPA proposed it for the National Priorities List in March 2011 and deferred to Oregon DEQ oversight in 2012. Documented contaminants are heavy metals, organotins, petroleum, and burn-pit/grit-pile debris. Neither the EPA profile nor the 70-page ATSDR health consultation identifies asbestos among the site's contaminants.
- Verification
- verified
- Role
- context
- Documentation level
- class_or_era
- Accessed
- 2026-10-04
- Study period
- 1924-2022 (site record); assessment 2016; cleanup 2020-2022
- Population
- AMCCO workers and neighboring community (site-era populations, post-1940s through cleanup 2020-22)
- Limitations
- Yard-site environmental record compiled decades after the wartime build; it documents the yard's postwar contamination profile, not wartime construction materials. 'No asbestos identified' in the environmental assessment is not evidence that asbestos products were never handled at the yard in 1943-44 - only that asbestos was not among the drivers of the site listing. Not a ship-specific record.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-07
-
[9]Batch-9063 search ledger (this record): NARA Special List 44; NHHC Online Reading Room; NAVPERS 15,790 via HyperWar; NavSource; Navpedia; uboat.net; Shipbuilding History (Tim Colton); EPA/ATSDR site file for the builder; CourtListener API v4 (4 base queries, all zero hits) [other_primary]
- Locator
- search_ledger rows sl-uss-yms-423-yms423-01 through sl-uss-yms-423-yms423-11
- Finding type
- historical_record
- Finding
- No qualifying ship-specific asbestos record located: no survey, abatement contract, hazmat disclosure, museum record, or docketed case naming YMS-423 was found in the public sources searched (see search_ledger). CourtListener exact-name and hull-number queries (opinions and RECAP dockets) each returned zero results. No class-level materials or industrial-hygiene document for the YMS-1 type was located either.
- Verification
- verified
- Role
- negative_finding
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 2026-10-04
- Limitations
- Absence of a located public record does not prove absence of asbestos aboard - WWII-era small craft did use asbestos in limited applications, and the deck-log and RG 19/BuShips records behind the archival leads have not been pulled. The zero-hit CourtListener results reflect indexed case-name/docket text only and do not sweep party-name or exhibit-list content. Does not establish that asbestos is or is not present aboard this hull; does not establish or defeat any claim of exposure or legal eligibility.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-08
-
[10]uboat.net Allied Warships entry for USS YMS-423 (corroborating compilation); NavSource vessel page; NAVPERS 15,790 ship list [other_primary]
- Locator
- uboat.net ship page data table; NavSource 19423.htm fate paragraph; NAVPERS Awards-IV-16 YMS-423 credit line
- Finding type
- historical_record
- Finding
- Source discrepancies on the record, preserved rather than silently reconciled: (a) the 25 October 1944 milestone reads 'Completed' on NavSource vs 'Commissioned' on uboat.net - NARA deck-log coverage beginning that day corroborates entry into service but does not settle the commissioning wording; (b) NavSource records the 26 December 1947 recipient as the 'War Shipping Administration' while uboat.net records 'sold' - the WSA ceased operating in 1946, so the receiving disposal agency (presumably the U.S. Maritime Commission) is unverified; (c) NAVPERS 15,790 prints the P207-9 Kobe credit ending '29 Feb 45' - an impossible date (1945 had no February 29) against an operation window ending 9 March 1946, read as 29 February 1946; (d) uboat.net alone supplies an order date of 21 July 1943.
- Verification
- partial
- Role
- correction
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1943-1949
- Limitations
- No primary commissioning, transfer, or disposal document was located, so none of these variants is resolved; each is carried attributed, not harmonized. The WSA-successor point is analytic (agency abolition is public administrative history) rather than vessel-specific.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-423-yms423-09