The shelves are pretty basic - just a 2'x8' piece of 1/2" plywood the kids were using as a ramp...
We cut the sheet in half, then installed a few eye-bolts. We'll screw the wood into the wall, and use rope and eye-bolts to hold up the edges.
Pretty quick to get up, and they work great! The best part is that they are up about 8' high, so we can easily walk underneath and get around the boat.
Nothing to interfere with moving the boat in and out, and they are up high - just right to load and unload into when up in the boat.