There was a report that she had been lost on a passage from Halifax, Nova Scotia, to Barbados, and some official mentions to that effect, but these are clearly in error.

Lloyd's List initially reported on 2 April 1811 that "HM schooner Shamrock" had been lost off Cape St Mary's, and that her crew had been saved.

[3] Lieutenant Croke was cruising south east of Cape St Vincent when Shamrock pursued two merchant vessels that she did not catch.

When the sun rose, Croke was able to see that Shamrock was about one and a half miles south of Cabo de Santa Maria.

The causes of the loss were a miscalculation in navigation and strong currents that had put Shamrock much further north than he had realized, but Croke had failed to take necessary precautions when approaching land.