Hundreds of pounds were wasted when two coastguard teams searched the River Crouch on Sunday after they received a hoax phone call.
Thames Coastguard were phoned by a sailor at around 9pm on Sunday who reported hearing a Mayday call on his radio.
Burnham on Crouch RNLI inshore lifeboats and the South Woodham Ferrers Coastguard team both investigated, a mission which cost the RNLI about £800.
They carried out an extensive search of the Bridgemarsh Marina, the River Crouch and the River Roach, but did not find anything.
No wreckage or bodies were reported the next day.
Thames Coastguard concluded the phone call was a hoax.