After naval service the yacht was again under the name Sea Wolf until sold in 1954 and renamed Miss Ann, listed on the U.S. National Register of Historic Places in 1998.

[3] Siele was built to a design by Benjamin T. Dobson[note 2] by Pusey and Jones Corporation, Wilmington, Delaware as yard hull 396, contract 1032 for John H. French, a Detroit banker.

The yacht was powered by two six cylinder, 300 horsepower (600 total) Winton diesel engines driving twin bronze screws.

[2] Assigned to the Naval Research Laboratory (NRL), Washington, D.C., Aquamarine assisted in experimental work, chiefly underwater sound.

[note 5] Although most of her experiments were conducted on the Potomac River and Chesapeake Bay, she also operated off New London, Connecticut, from 16 October to 4 November 1943, and off the Florida coast and in the Bahamas from 24 January 1944 to 18 April 1945.

[2] Among the experiments was use of Aquamarine and Accentor for shallow water sound propagation research in the Potomac using frequencies of 70–400 Hz and sampling bottom sediment characteristics.

[7][12][15][18] Stephens had to essentially rebuild major portions of the vessel and had an arrangement with Grimm regarding the Winton diesels and Navy installed gyrocompass.

One of the Navy modifications Stephens notes were "two cylinders, approximately three feet in diameter each, through the deck and all the way through the ship" which were possibly part of the research in generating a bubble cloud to reduce noise as they somewhat fit the NRL description of pipes near the bow through which perforated fire hoses were passed.

[12][note 6] After the Coast Guard found the vessel in violation of rules regarding carrying passengers Stephens spent about a million dollars undertaking repairs below the water line to come into compliance.