keeping snow off the cover

[oteps]

My new boat has a canvas cover, prop in the back with 2 straps the run from front to back, 2 bowed flat pieces of metal in the front that go to the side rails and a cable across the rails so the dont spread and break. But the snow still pushes the canvas down and im afraid its going to collapse. Might throw a tarp over some of it but That wont let the canvas breathe. I cant get the cover any higher in the center so the snow slides off.
What do u guys do?