Thank you for your inquiry, which led me on a merry chase. I have useful information for you.
While it is no reflection on you, it appears that your original information is incorrect in several respects. First, I believe the man in question was not named Benedict Lipp but rather Benedict Lipskas. Further, he was not part of the U.S. Navy Armed Guard but rather a civilian merchant mariner, part of the operating crew of the ship that was sunk resulting in his death.
I found information on the loss of Benedict Lipskas on the website American Merchant Marine at War: see http://www.usmm.org/killed/l.html and scroll down to his name. You will note that his hometown is listed as North Wilmington, Massachusetts, and that his date of death (or date he went missing in his case) was March 29, 1943. Moreover, he is identified as a merchant mariner, specifically an able-bodied seaman (A.B.), on a vessel named SS WILLIAM PIERCE FRYE. These bits of information, although limited, match nicely with other of the information you have.
WILLIAM PIERCE FRYE was sunk by U-boat 610 in the Atlantic southwest of Iceland. For a description of the engagement (at least in part based on German U-boat records), see https://uboat.net/allies/merchants/ship/2830.html. An accompanying page lists the crew who were lost, a total of 57, including Benedict Lipskas, and has a photograph of the ship; see https://uboat.net/allies/merchants/crews/ship2830.html. According to these pages, seven members of the crew survived although they are not identified.
(U-610 was later sunk on October 8, 1943, in the North Atlantic northwest of Ireland, in position 55.45N, 24.33W, by depth charges from a Canadian Sunderland aircraft. All hands were lost, a total of 51 men. See https://uboat.net/boats/u610.htm.)
WILLIAM PIERCE FRYE was a Liberty ship, one of more than 2,700 virtually identical ships that were constructed immediately before, during and immediately after World War II, the largest single class of ship ever constructed. Liberty ships were the most numerous and common of all merchant ships that operated in the war; many continued in service with private shipping companies for many years thereafter. WILLIAM PIERCE FRYE was constructed in 100 days between November 1942 and February 1943 by the New England Shipbuilding Co., South Portland, Maine. See http://shipbuildinghistory.com/shipyards/emergencylarge/newengland.htm and scroll to hull number 212. It is very likely that she was on her maiden voyage when she was lost. Also see http://www.mariners-l.co.uk/LibShipsW-Z.html and scroll to the name of the ship, although this link provides very little additional information.
To expand upon the information from www.uboat.net above, WILLIAM PIERCE FRYE was a part of convoy HX-230 that departed New York City on March 18, 1943 (see http://www.convoyweb.org.uk/hx/index.html?hx.php?convoy=230!~hxmain). The convoy’s destination was Liverpool, with WILLIAM PIERCE FRYE scheduled to continue to Barry, Wales, south of Liverpool. Her cargo included wheat, explosives, general cargo and five LCT landing craft on deck. The ship straggled, meaning she dropped out of the convoy, typically for mechanical reasons. She was torpedoed and sunk by U-610 about 390 nm SSE of Vik, Iceland, at 56 57N, 24 15W. She had fallen behind the convoy on March 23 to stop to repair an engine problem. When torpedoed, most of her lifeboats were already badly damaged or lost in heavy seas or were destroyed in the torpedo explosion. One LCT floated off as she was sinking and saved a few lives. Other crewmen who crowded into the lone useable lifeboat were lost.
The ship was named for William Pierce Frye (1831-1911), a lawyer. U.S. Congressman and U.S. Senator from Maine who was a strong supporter of the U.S. merchant marine.
I am unable to find additional information about Benedict Lipskas although I did find his grave marker that you referenced (https://www.findagrave.com/memorial/174760795) as Benedict Lipp. I suspect there is more information to be found about him somewhere although I also suspect he may have used other names, Lipp being one; Lipska is another possibility. I note above that he was an able-bodied seaman, which is a merchant marine rating for a journeyman deck crewman. Therefore, he must have had sailing experience prior to March 1943 in order to have qualified for the A.B. rating.
I don’t know of course whether you wish to pursue the story of Benedict Lipskas/Lipp any further but if so you now have some additional material with which to work. One possible avenue is to attempt to obtain his official merchant marine service record. See this page from the website I manage, http://www.armed-guard.com/searchmil.html, and follow the information at section II.A.2, Records of Individuals – Merchant Marine. Note that because Lipskas/Lipp was killed during World War II, you will have to contact the National Archives and Records Administration in Washington, DC. A postal address and an e-mail address are noted on the page. There will be a fee for researching, copying and mailing (assuming the man can be identified by one name or another) but the Archives staff will inform you of any fee before commencing work on your request.
Ron Carlson, Webmaster
Armed Guard / Merchant Marine website