The United States Lightship WLV-613 (Ambrose) was a lightvessel commissioned in 1952 that became the last lightship to mark the Ambrose Channel. She was replaced by a Texas Tower lightstation on 24 August 1967.
The Ambrose was reassigned as a relief ship on the Massachusetts coastline from 1967–79. After being renamed Nantucket II, in 1979, she was reassigned to Nantucket Shoals. She alternated with her sister ship, the Lightship Nantucket WLV-612 relieving each other approximately every 21 days. The Ambrose was also the last lightship to mark the Nantucket channel on 20 December 1983. She was decommissioned and retired in 1983.
Ambrose was berthed at the Wareham Shipyard along Main Street in Wareham, Massachusetts from about 1990 until she was moved to New Bedford, Massachusetts on December 1, 2014. The Ambrose (now painted as "NANTUCKET") is now privately owned by William B. Golden, owner of Nantucket I. It is planned to renovate her in 2015 and use her to host private events and overnight guests. Currently, she is closed to the public.
- "LIGHTSHIP WLV 613". U.S. Coast Guard Lightships & Those of the U.S. Lighthouse Service. The United States Coast Guard. Retrieved 31 October 2010.
- Lightship Nantucket II WLV 613, MA