RNLI Angle's all weather lifeboat was alerted late on Sunday night, after a report that a speedboat had broken down and was believed to be drifting towards the Pembroke Dock ferry terminal.
The speedboat, with two people on board, had no lighting or lifesaving equipment.
The Tamar class lifeboat Mark Mason was launched at 11.19 pm and, while proceeding to the scene, it was confirmed that another vessel was assisting the casualty. It also had no navigation lights, but was making slow progress due to the current of the tide.
Once on the scene at 11.36 pm, and with no vessels in sight, a search was conducted using radar and searchlights, but nothing was found.
While the Mark Mason was passing Hobbs Point, Pembroke Dock, two members of the public told the lifeboat that the speedboat had been towed towards Neyland. En route there, the lifeboat was informed that the casualty had notified Milford Haven Coastguard that it was safely secured to a berth.
The lifeboat then proceeded to Neyland pontoon, where she offered some advice to those concerned. She was then released to return to her station, where she was rehoused at 12.33 am.
It was the second call-out in three days for the lifeboat station. On Friday evening, the all weather and inshore lifeboats were requested to launch at 6.44 pm, after a report that a child was in the water and shouting for help, off Milford Docks.
While the lifeboat crew were mustering at the station, it was confirmed that a passing leisure craft had responded and had assisted the child to safety.
With no assistance required, both boats were stood down at 6.50 pm.