RedactedNarrative: Operator of vessel was transiting from east end of lake toward Brewerton.  Operator was unfamiliar with lake and using channel the buoys to navigate by.  Operator lost sight of buoys in reduced visibility and attempted to navigate solely off chart plotter.  He proceeded to pass Dunham and Frenchman Islands on the south side and ran into a marked shoal.  Vessel sustained damage to props, shafts and rudder.