Inshore lifeboat launched at 1338 to report of drifting dinghy in vicinity of Queenborough harbour with one teenage person onboard. ILB on scene at 1347, casualty aground on mudflats, some 50 mtrs from the water’s edge and approx. 150 mtrs from the shore. Crewman made his way slowly across the mud, person okay, but too dangerous to extricate him back to ILB, as he was ill dressed for being afloat and had no safety equipment with him. Crewman returned to ILB and proceeded to another craft, where his Mother was onboard, after collecting lifejacket and foul weather clothing, food and drink, the ILB returned to the casualty and clothing was walked across to him. Person was happy to remain onboard his dinghy and with UKCG in agreement, the ILB was released and returned to station at 1500. Wstly 6.