Marine police helped rescue sailors whose boat lost power in the Blackwater Estuary.
The yacht was in danger of grounding onto a leeward shore when its engine cut out on Sunday.
Two officers from the Essex Counter Terrorism Marine Unit, who were at Tollesbury Marina, answered a call put out by the Thames Coastguard.
After checking the crew’s welfare, they towed it to Bradwell Marina.
Det Sgt Vaughn High, who supervises the unit, said: "The maritime community was pleased to observe police activity on the water and it was fortunate that they were patrolling with a fast response vessel.
“The unit would always respond to any search and rescue incident where there could be an immediate threat to life.”