The Oathtaker began life as a tramp freighter along the coasts of Sembia in Faerun. About ten years after her launching she was purchases by a pirate/smuggler named Delian Dolphinslayer (CE hm F9). This gentleman used the vessels unassuming appearence and lack of armament to facilitate returning the goods he'd captured with his flagship, a wargalley named the "Tempest". Because the Tempest was well known along the coast, as was Delian himself, he had to trust a mate to make these cargo runs. All went well for several years, until the mate was seduced by a female mage (of the Zhentarim), She persuaded him, and the crew, to accept a charter from a small band of adventurers from Hill's Edge. Unfortunately for the mage and the mate, the adventurer's overcame the entire crew and took the vessel for their own. They gave themselves the name "Oathbound" and named their vessel the Oathtaker. Powering the ship with a furnace helm they had discovered in an earlier adventure they took to space, just in time to become embroiled in the Second Unhuman War and the affairs of a radient dragon. They sailed the spacelanes between Bral and the Realms for several months, slowly defeating their enemies while searching for an unknown magical artifact. During this time they upgraded the oathtaker to her current status.
Finding deception an important tool, they installed heavy weaponry inside the hull of the oath bound, showing only a light catapult to the casual observer. the ballista's fire from portholes (exactly like cannon fired out of a frigate or pirate vessel in the Eorl Flynn movies). Rather than keep a large crew on board, they alternated crew their heavy weapons and loaded them at the first sign of trouble.
The group eventually returned to Faerun, where they engaged in some large groundling battles with the Zhentarim over Hill's Edge. it's unknown wether they sold the Oathtaker or have simply kept her hidden. No one has reliably spotted her in space recently.