i used 1/2" emt last year to build a frame and bought some tarps from home depot. i used 3 tarps for my 30'er. one went from the stern to the mast on the port side, one from stern to mast on starboard, and one from mast to bow. with all the rigging, it wasn't a very tight fit around all the rigging but it probably kept out about 90% of the snow and worked pretty good.
s/v Time Flies