June 11/13-A privately operated float-equipped Cessna 180, C-GVRG, was departing southbound from Boggy Creek Bay on Lee River, MB. Shortly after take-off the aircraft experienced a partial loss of engine power (Continental 0-470-K). During the subsequent forced landing, the aircraft collided with trees and then crashed into a field. The pilot and passenger sustained serious injuries. The aircraft was substantially damaged by impact forces. There was no post-impact fire. TSB examination of the engine revealed that hose clamps used to secure the induction crossover-tube seals had not been re-tightened after recent maintenance. During take-off one of the induction seals became misplaced causing a major induction leak and loss of engine power. The AMO is reviewing their maintenance practices and procedures.