Coastguard and lifeboat teams were called to reports of a yacht dragging its anchor in Portland Harbour.
Coastguard teams from Wyke and Portland Bill were called at around 11.15 pm on Saturday evening.
Weymouth Lifeboat's all-weather boat (ALB) was already at sea having been launched to multiple incidents earlier in the evening.
The lifeboat took the yacht undertow.
A second vessel was observed entering dangerously shallow water trying to anchor and was kept under observation until safely back in deep water
A spokesperson for Wyke Coastguard said: "We were tasked to reports of a yacht dragging its anchor in Portland Harbour with 7 POB along with Portland Bill Coastguard Rescue Team.
"Weymouth Lifeboat ALB, which was at sea having been launched earlier to multiple incidents involving some of the Fastnet fleet arrived and took the vessel undertow.
"A second vessel was observed entering dangerously shallow water trying to anchor and was kept under observation until safely back in deep water."
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