A search and rescue operation launched after mayday distress call was made has now been called off.
The authorities believe the call was a hoax.
The Lee-on-the-Solent and Portland helicopters were sent out across the area after receiving the call from the Air Rescue Co-Ordination Centre (ARCC) just after midday.
The helicopters searched around Bexhill through to Shoreham, over to the Isle of Wight and on to Portland, but nothing was found.
It is now believed to have been a false alarm, and there are also concerns it could have been a hoax.
Mark Clark, spokesman for Solent coastguard, said: ‘It’s not unusual unfortunately. It sounded genuine enough for us to send out a couple of helicopters but we would do that on a mayday signal.
‘These guys are trying to respond and they feel as frustrated as anybody because they aren’t able to carry out their jobs properly.
‘They get a sense of frustration that somebody is messing around.’