Kent Police are appealing for information after a capsized catamaran was discovered about 27 miles north-east of North Foreland in Thanet.
The vessel was spotted shortly after 8pm on Saturday evening and was found to have a black North Face rucksack on board containing items of clothing, maps and a small quantity of cash.
Coastguard crews searched the area in the Thames Estuary overnight but nothing further has been discovered.
RNLI all-weather lifeboats from Margate and Ramsgate were tasked, along with the coastguard helicopter from Lydd Airport and shore-based coastguard rescue teams.
Margate lifeboat was able to right the craft and some personal belongings recovered and an extensive search of the area was carried out.
The catamaran is a white New Cat 12 model with the serial number 7064-1999 and make number K-0566. It has been recovered and is now being kept at the Port of Ramsgate.