RedactedNarrative: V1 was traveling south and westerly on the South Fork of the St. Lucie River, Martin County, heading toward the Thomas B. Manual Fixed Bridge and the St. Lucie Lock heading into Lake Okeechobee Waterway. The Operator indicated it was a 25 MPH zone and he was going the speed limit. He was using electronic means (Garmin and depth sounder) as well as visual means to maintain look out. He was approaching Red Marker 38 when his Garmin indicated V1 should pass the marker on its right side. However, the vessel was actually outside the marked channel and the marker was on the left. V1 ran hard aground and Occupants 1 and 2 were thrown forward. Occupant 1 was critically injured as a result of the sudden grounding and fell within V1. She struck the sliding partition for the berthing quarters and fell down inside the berthing area. Occupant 1 was flown to Lawnwood Regional InFort Pierce, St. Lucie County in critical condition. Injuries were: Lacerations to right ring finger, eyelid, face and head/scalp. The back injury/spinal injury included broken ribs, and a T11/12 fracture. The broken bones included 3 fractures to the left pelvis and 1 fracture on the right pelvis. She was in shock. Her fractures included a left, wrist distal radius and ulna bone fractures. The wrist fracture resulted in two surgeries. She had a small contusion on her cheek and shoulder.