The woman, who was accompanied by her husband aboard the 30ft motorboat Seajay on a mooring off The Folly, was said to have banged her head when she fell over and was feeling unwell.
The lifeboat took the woman to the Folly Pontoon where Newport Coastguard helped to transfer the woman to an awaiting ambulance which took her on to St Mary’s Hospital.
The lifeboat, which had launched at 03:50, returned to station an hour later.
On Saturday Cowes lifeboat joined Lymington’s RNLI lifeboat and Coastguard Rescue 104 helicopter to search the Newtown area after an empty 3m inflatable dinghy with its outboard still down was found drifting in the area.
The search was eventually called off when nothing more was found.