This is my first experience with mid-boom sheeting. The mainsheet on my Ericson 28 goes from the traveler to the mast, up the mast then down the boom. Where it passes the Vang it rubs. Is this normal? Is there a way to avoid this? The mainsheet doesn't run as freely as I would like. I am removing the what seems to be about 7/16" line and changing it to 3/8" but I still think that it is going to rub.