It was about this time yesterday afternoon when I copied a MAYDAY call on Ch 16 VHF-FM and found the position to be approximately 3 miles ahead of me. A 29 ft Pleasure Craft ran hard aground while doing 30-40mph and had a severely injured crewman onboard. One fisherman (retired Firefighter) and a towboat had responded. I continued to monitor the situation, via the radio, and when it was announced that they needed a backboard and First Aid Supplies, I responded. I woke the off watch crew, launched our small boat and reached the scene withing a few minutes. The patient had flown from the cockpit down into the main salon upon impact, striking the Galley table along the way. I found a large lump on the right back of the head, a hematoma on the left forearm, a possible hairline fracture on the right forearm, three bruised ribs on her right side, and bad hip pain. we got her iced in places and then the USCG arrived in a small boat and we departed to make room. The USCG Helo arrived as we departed and the patient was airlifted to a Galveston or Houston Hospital. I left our backboard at the request of the USCG (to help get her out of the boat to a hoist position). We'll pick up our backboard when we pass through the Brazos River Floodgates on our return trip to Houston.