Dear Mr. Hurley,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the Logbooks of U.S. Navy Ships and Stations, 1941 - 1983 in the Records of the Bureau of Naval Personnel (Record Group 24) that include the deck logs of the USS PC-621 for December 1942 through October 1944. We also located World War II Action and Operational Reports in the Records of the Office of the Chief of Naval Operations (Record Group 38) that may include reports submitted by the USS PC-621. These records have not been digitized and are not available online. For more information, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT2. We apologize for this inconvenience and appreciate your understanding and patience.
We also located World War II War Diaries, Other Operational Records and Histories, ca. 1/1/1942 - ca. 6/1/1946 in the Records of the Office of the Chief of Naval Operations (Record Group 38) which contains war diaries and reports concerning the USS PC-621’s activities during portions of 1944. These records have been digitized and can be viewed online through the Catalog. Please note that the Catalog does not always list files in chronological order.
Finally, the unofficial website NavSource has a page on the PC-621.
We hope this is helpful. Best of luck with your research!