Adonia had undergone drydock work at Grand Bahama Shipyard prior to its April 10 maiden sailing, which was to be a 'soft launch' with a large number of travel agents on board.
A statement from Carnival Corp. & plc said Fathom's April 17 voyage to the Dominican Republic would go ahead.
The company said the USCG inspection involved a number of tests that had not previously been performed on the ship, that testing took longer than expected and that further tests were needed. Adonia's technical management is handled by P&O Cruises.
Adonia has been sailing for P&O until now.
Passengers on the April 10 voyage received full reimbursement for expenses and credits toward future cruises.
(Editor's note: See subsequent story outlining the remaining deficiency.)