Two people swam from their boat to the Isle of Grain after they got into difficulties when the engine failed.

Thames Coastguard said the pair were in the water for half an hour with one suffering from hypothermia.

Lifeboats from Sheerness and Southend, together with Medway Coastguard, were called out to the incident which happened shortly after midnight on Sunday.

The man and woman were airlifted to Southend Hospital by helicopter.

Coastguards said the boat had no flares or tracking equipment so the couple were unable to help rescue services locate them.

Thames Coastguard watch manager Amee Neale said they had only managed to grab one life jacket, which the man gave to the woman.

She said: “You don’t need sophisticated and expensive tracking equipment.

"Just a normal VHF marine radio will enable us to find people using our direction finding equipment.

“It’s important that people who go to sea not only have flares and life jackets, but that they keep them where they can be easily reached in emergency.

"They should also ensure they have an anchor on board with sufficient cable.”