The 32-year-old male member of staff was successfully recovered from the water by colleagues but had sustained a suspected broken rib.
The Alfred Albert Williams Tamar-class Lifeboat powered away from the boat house at Lanes End and reached the Fort at 02:52.
2 crew members were put onto the Fort with a stretcher which the injured man was placed into and subsequently transferred to the lifeboat.
Bembridge Lifeboat left for Portsmouth at 03:30 and was alongside The Camber by 03:50.
Having handed the casualty over to South Central Ambulance Service, Bembridge Lifeboat returned to station and was recovered by 05:00.