My Prindle 19 stock mainsheet is a 7/16 dia, however I replaced it for a 3/8 and gloves and everything was fine over the summer while we had light winds. The last two times I've been out in 10 to 15 knts it is very tiring and I am considering returning to the old line. However, after doing some research in this forum the carbo ratchamatic block appears to be a solution. Will they help if I continue to use the 3/8 dia line?. Any help is really appreciated.....Going to the gym and attaching a line to the rowing machine is not a solution.