We used 90% greenhouse shade fabric
, ziptied to PVC poles that we then tie to the split backstays
and shrouds at the mast
. It doesn't need much structure because wind
blows right through it.
I had a ShadeTree on my previous boat. It's great -- easy to setup, we could walk underneath it, and the covered wagon look is fun. But it can be hot, the fabric
heats up and radiates heat down. I think porous fabric, that lets wind
blow through it, is cooler.
To me, ideal would be a combination of the covered wagon hoops of the ShadeTree structure with two layers of black 90% greenhouse fabric. This is a common shade structure at Burning Man, where it's way hotter.