At Ancestry there is a US Passengers and Crew lists datbase. There are also more such lists in books and microfilm at a LDS Family History Center as well as NARA Libraries, I believe. Also look at http://www.usmm.org/http://www.usmm.org/
I find he was signed on as crew of the MS Tidewater June 18, 1943 when it arrived at the port of NY on that date. It left the port of Clyde, Scotland He was age 19. Another entry states he was discharged from Tidewater 6/21/1843 with the arrival date 6/30/1943. Last entry is he was a "messboy" his first trip on Tidewater engaged 6/19/1943, arrival date of 6/30/1943 in NY, left Glasgow, Scotland.
He was also in the Navy...
According to the Veterans Gravesite Database he was an S2 in U.S. Navy so his service records will be at the NARA. Luckily Navy Service records were not involved in the 1973 fire. www.archives.gov
From Veterans BIRLS file on Ancestry he enlisted 1 Mar 1944 and was released from Service 2 Feb 1945. From Navy Muster Rolls also on Ancestry Harold Erwin Lehmuth USNR was on the ship YMS 268 crew lists from quarter ending June 30, 1944 to quarter ending Oct 31, 1944. His service number was 896 14 91. You will need it to order service records. If you are next of kin as defined by NARA.
He was transferred Oct 9th 1944 from YMS 268 to SCTC Terminal Island, California. That was a base sailors were sent to await their discharge from active service.