Littlehampton RNLI went to help a yacht which had run aground on Rustington beach after receiving a call from the UK Coastguard.
A member of the public called it in just after 4.35pm on Saturday.
The station’s Atlantic 85 lifeboat Renée Sherman and volunteer crew headed out of the harbour towards Rustington in fine weather conditions.
The yacht with one man on board had run aground onto the beach. RNLI lifeguards were already with the man when the lifeboat arrived and reported that he had left the vessel and had swum ashore.
They said he appeared to be disorientated and had walked away from the beach.
One of the lifeboat crew went aboard the vessel and with the assistance of the lifeguards a tow line was rigged up and the yacht was towed back to Littlehampton harbour, where it was safely secured alongside Town Quay.
The lifeboat returned to the station at 6.51pm.
The man was later found and taken back to the lifeboat station, where an ambulance was waiting.
He said he felt confused and described himself as feeling groggy, following a single-handed journey from Falmouth. He had been heading to Brighton Marina.
He was looked over by paramedics.