Evidence
11 evidence entries recorded; each entry has a stable permalink (#ev-1 … #ev-11).
-
[1]research packet 1068-packet.md (2 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-421-yms421-pkt-1068-packet-md
-
[2]NavSource Online: Mine Warfare Vessel Photo Archive, YMS-421 page - build/loss timeline, specifications, call sign (verified live, HTTP 200) [other_primary]
- Locator
- NavSource 11/19421.htm header block and specifications block
- Finding type
- vessel_history
- Finding
- Documented for this hull: YMS-1 Class Auxiliary Motor Minesweeper; laid down 20 September 1943 by Henry C. Grebe and Co., Chicago, IL; launched 15 April 1944; completed 3 March 1945; 'Foundered in a typhoon off Okinawa 16 September 1945'; struck from the Navy Register 24 October 1945. Call sign November-Papa-Zulu-Uniform. Specifications: displacement 270 t.; length 136'; beam 24' 6"; draft 8'; speed 13 kts; complement 50; armament one single 3"/50 gun mount; propulsion 'two 880 shp General Motors diesel engines, two shafts.' Page explicitly states 'There is no DANFS History currently available for YMS-421' and no image of the vessel is held.
- Verification
- verified
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1943-1945
- Population
- Grebe construction trades (1943-45); crew (Mar-Sep 1945)
- Limitations
- NavSource is a volunteer secondary compilation, not a primary registry - its milestone dates generally track NVR/DANFS but are not themselves primary. 'Completed' vs 'commissioned' wording varies across sources (see gaps). No asbestos or material content. No DANFS entry exists for this hull, so NavSource is the most complete single timeline located.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-01
-
[3]NHHC, 'Casualties: U.S. Navy and Coast Guard Ships' (official Navy casualty list for vessels sunk or damaged beyond repair, WWII) - verified live [nhhc_danfs]
- Locator
- NHHC casualties page, minesweeper loss entries (YMS-385 through YMS-481 block)
- Finding type
- vessel_history
- Finding
- Official Navy listing of the loss: 'USS YMS-421 sunk off Okinawa, Ryukyu Islands, 16 September 1945.' The same list records sister YMS-472 'sunk off Okinawa, Ryukyu Islands, 16 September 1945' - the shared storm event (Typhoon Ida).
- Verification
- verified
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1945-09-16
- Population
- Crew aboard at loss (Sep 1945)
- Limitations
- Official casualty list establishes loss event, date, and general location only - no cause detail beyond 'sunk,' no casualty roster, no salvage/disposition record. No asbestos content. Not to be confused with the better-known Typhoon Louise event at Okinawa of 9-10 October 1945 (NHHC 'Pacific Typhoon October 1945' page lists a different set of YMS losses/groundings and does not include YMS-421).
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-02
-
[4]NHHC, 'United States Pacific Fleet Organization, 1 May 1945' (reproduced official fleet organization) - verified live [nhhc_danfs]
- Locator
- PacFlt org table, MINECRAFT PACIFIC FLEET > MINE SQUADRON TWENTY, YMS block (p. ~132 of source document)
- Finding type
- historical_record
- Finding
- As of 1 May 1945, YMS-421 was assigned to MINE SQUADRON TWENTY (Commander Mine Squadron TWENTY: Capt. R. A. Larkin; flagship USS Ellyson, DMS-19), under Minecraft, Pacific Fleet (R. Adm. A. Sharp). Her entry carries a '(1)' annotation and the command column is blank ('..........') - no commanding officer named. Sister/neighbor hulls in the same squadron listing include YMS-403 through YMS-434.
- Verification
- verified
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1945-05-01
- Population
- Crew (May 1945)
- Limitations
- Fleet-organization snapshot at a single date (1 May 1945) - documents assignment, not movements or operations. The '(1)' footnote marker's definition was not recoverable from the HTML page (footnote legend not exposed); carried undecoded. Four months elapsed between this snapshot and her loss - later reassignment is possible (the September operational record for sister boats names Mine Squadron 4 at Unten Ko, not MinRon 20). No asbestos content.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-03
-
[5]NARA, Special List #44 - 'List of Logbooks of U.S. Navy Ships, Stations, and Miscellaneous Units, 1801-1947' (ship-number order), PDF page 121 (verified via direct download) [other_primary]
- Locator
- sl-44-ship-number.pdf p.121, row 'YMS-421 4/12/1945 8/31/1945'; digitized-logs check at archives.gov/research/military/logbooks/navy-online
- Finding type
- historical_record
- Finding
- NARA holds deck logs for YMS-421 covering 12 April 1945 - 31 August 1945 (RG 24, Bureau of Naval Personnel logbooks). The coverage window is consistent with her documented service life: completed 3 March 1945 in Chicago, lost 16 September 1945 - no September 1945 logs exist in the inventory (final entries were presumably lost with the ship or never forwarded). The logs are the lead for reconstructing her April-August 1945 movements (fitting-out, transit from the Great Lakes to the Pacific, arrival in the Okinawa operating area) which are otherwise undocumented in the sources used.
- Verification
- verified
- Role
- archival_lead
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1945-04-12 to 1945-08-31
- Population
- Crew (Apr-Aug 1945 log coverage)
- Limitations
- Archival lead only: the inventory proves logs exist and gives their date span - it is NOT the logs' content. The logs are not digitized (YMS-421 does not appear on the NARA 'Navy Deck Logs Available in the National Archives Catalog' page, which lists only digitized vessels; only AMS/MSCO-converted sisters appear). Physical access at NARA required. No asbestos content.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-04
-
[6]naval-history.net transcription of U.S. Navy WWII casualty lists (by-name database) - two YMS-421 crewmembers listed; corroborated by honorstates.org memorial entry for Tsikalas [other_primary]
- Locator
- WW2UScasaaDB-USNbyNameS.htm (Salinas) and ...byNameT.htm (Tsikalas); honorstates.org profile id=361831
- Finding type
- historical_record
- Finding
- Personnel losses documented aboard this hull: SALINAS, Luz R., Ship's Cook Second Class (SEA2), USNR, service no. 8422328, of New Mexico - 'USS YMS-421, location Japan, missing, date of loss September 16, 1945,' memorialized Honolulu Memorial; and TSIKALAS, Jimmy G., Seaman First Class, USNR, no. 6526636, of Pennsylvania - same listing ('missing, date of loss September 16, 1945, location Japan,' Honolulu Memorial). These are the only two names keyed to USS YMS-421 across the 26 letter-files of the transcribed database.
- Verification
- partial
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1945-09-16
- Population
- Crew aboard at loss (Sep 1945) - Salinas, Tsikalas confirmed lost
- Limitations
- Incomplete roster: two names in a transcribed casualty database do not establish the total dead/missing, and absence of other names does not prove the rest of the crew survived. naval-history.net is a transcription of official Navy casualty lists - high fidelity but not itself primary; ABMC decedent-search direct verification was attempted and blocked (HTTP 403). Whether any crew were rescued is unestablished. No asbestos content.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-05
-
[7]Naval Marine Archive, 'Yard Minesweepers YMS BYMS' builder/disposition table (secondary compilation) [other_primary]
- Locator
- navalmarinearchive.com/sbh/smallships/ym.html, YMS-421 row and Grebe row count (25)
- Finding type
- vessel_history
- Finding
- Builder-program context for this hull: the table lists exactly 25 YMS-type minesweepers built by Henry C. Grebe & Co., Chicago (YMS-84, -85, -171 through -182, -279, -280, -405 through -409, -418 through -421), with YMS-421 the last delivered (3-Mar-45). Independently corroborates the Chicago industrial-history claim that YMS-421 was Grebe's 25th and final Navy minesweeper. NOTE: the table's disposition column prints 'Lost 1946' for YMS-421 - a one-year date slip; NHHC and NavSource both carry 16 September 1945, and the 1945 date is carried in this record.
- Verification
- partial
- Role
- context
- Documentation level
- ship_specific
- Accessed
- 2026-10-04
- Study period
- 1941-1945
- Population
- Grebe construction trades (1941-45)
- Limitations
- Secondary compilation used for the builder-count corroboration only; its 'Lost 1946' disposition for this hull is wrong and is logged as a source defect rather than propagated. No asbestos content.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-06
-
[8]NHHC National Museum of the U.S. Navy, 'YMS-445, 1945-47' (program context for the YMS type) [nhhc_danfs]
- Locator
- NHHC NMUSN photography pages, 'YMS-445, 1945-47' object description
- Finding type
- vessel_history
- Finding
- NHHC's description of the type YMS-421 belonged to: 'These yard craft patrolled navy yards and adjacent areas, and they were also used by the Allies as part of the Lend-Lease Program.' YMS-445 was 'the last YMS ordered for World War II'; 35 additional motor minesweepers were originally ordered as submarine chasers. Class program context only.
- Verification
- verified
- Role
- context
- Documentation level
- class_or_era
- Accessed
- 2026-10-04
- Study period
- 1941-1947 (program era)
- Population
- Class crews generally
- Limitations
- Class/program description keyed to a sister hull (YMS-445) - does not name or document YMS-421. 'Patrolled navy yards and adjacent areas' describes the design role; Pacific forward-area minesweeping service (as actually performed by YMS-421) exceeded that framing. No asbestos content.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-07
-
[9]Era inference built on: NavSource specifications for this hull plus NavSource YMS index ('the first wooden minesweeper of this class'; 'a total of 561 were built... Built at 35 yacht yards'); NHHC YMS program context (ev-07); GAO HRD-80-2 (ev-09) [other_primary]
- Locator
- NavSource 11/19421.htm specifications block; NavSource archives/11/19idx.htm class index; NHHC YMS-445 program page; GAO HRD-80-2
- Finding type
- asbestos_application
- Finding
- A diesel-powered wooden-hulled minesweeper completed March 1945 sits inside the Navy's documented asbestos-use era; era-standard applications aboard a diesel craft of this type and period were engine and exhaust lagging, machinery gaskets and valve packing, and electrical insulation in the engine room and wiring. As a wooden-hulled craft built for non-magnetic minesweeping she carried no steam plant - the boiler/turbine lagging pathway of steam vessels does not apply, and her asbestos inventory would have been materially lighter than a steam combatant's, concentrated around machinery exhaust and electrical components.
- Verification
- inferred
- Role
- supporting
- Documentation level
- class_or_era
- Accessed
- 2026-10-04
- Study period
- 1943-1945
- Population
- Grebe construction trades (1943-45); crew (Mar-Sep 1945)
- Limitations
- Class/era inference only - no hull-specific insulation survey, material list, or work package located for YMS-421. Names era-standard applications, not confirmed installed materials. No quantity. Product names are normalized era terms; no manufacturer attribution for this hull. Her six-month service life and typhoon loss also mean no overhaul/refit windows in which additional insulation was typically installed.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-08
-
[10]GAO, Navy Efforts To Protect Workers From Asbestos Exposure, HRD-80-2 (Oct 18, 1979) [gao]
- Locator
- GAO product page HRD-80-2 (full text blocked, HTTP 403)
- Finding type
- gov_survey
- Finding
- GAO documented that the Navy used asbestos insulation extensively aboard ships and did not begin substituting alternative insulation materials until the early 1970s - spanning this hull's entire construction (1943-45) and service era (Mar-Sep 1945).
- Verification
- verified
- Role
- context
- Documentation level
- class_or_era
- Accessed
- 2026-10-04
- Study period
- 1979
- Population
- Navy shipyard workers; asbestos program review
- Limitations
- Program-level documentation; supports era context only, not any fact specific to this hull. Full text not retrieved (gao.gov blocks automated fetch, HTTP 403 - standing defect noted since Batch 01) - content via product-page description.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-09
-
[11]Batch-9061 search ledger (this record): NavSource; NHHC casualties page; NHHC Pacific Fleet organization 1 May 1945; NARA Special List 44 (direct PDF pull); NARA digitized-logs index; naval-history.net casualty transcription; Naval Marine Archive builder table; NHHC YMS-445 program page; uboat.net; CourtListener (via authenticated helper); wrecksite.eu (blocked); ABMC (blocked); secondary web litigation sweep [other_primary]
- Locator
- search_ledger rows sl-uss-yms-421-yms421-01 through -21
- Finding type
- historical_record
- Finding
- No qualifying ship-specific asbestos record located: no asbestos survey, abatement contract, hazmat disclosure, or litigation naming USS YMS-421 was found in the public sources searched (see search_ledger). No DANFS entry exists for this hull. The only 'asbestos aboard' material encountered was law-firm listicle content asserting asbestos without primary sourcing - excluded by source policy. Secondary web sweeps surfaced no qualifying case.
- 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. The deck logs (RG 24, undigitized) and builder records are the open leads. Does not establish or defeat any claim of exposure or legal eligibility.
- Atlas source
- true
- Evidence ID
- ev-uss-yms-421-yms421-10