Will tarp be a single piece or multiple pieces? What's the weight of the tarp? how do you make sure it's on the surface? Or do you need a support structure to keep it above the surface (say a meter etc.)? Will it have holes to drain? Will holes be sturdy enough in the long run? etc...

I was thinking why they use ball form instead of something sheet-like. E.g. thin pancake - it will have same properties as the balls but will cover surface more efficiently, if you count material.

> One would think that a tarp would use less material and be easier to manufacture than the equivalent number of plastic balls.

How do you suspend the tarp? What about when it rains on the tarp, increasing its weight substantially? Repair the tarp when sections get damaged? UV resistance over its lifetime?

Using barges/boats and dragging it from shore-to-shore is very slow going, and any suitably durable tarp (i.e. waxed canvas or some plastic) is going to be HEAVY.

Repair, weight, suspension and deployment seems like the hardest issues to tackle.

The tarp would ideally need to be reflective, like a white roof on modern buildings. The rain issue is the easiest one to solve, since the tarp could be slightly perforated to allow drainage.

I wonder if a permanent structure over the lake would be easier than a tarp? Like literally building a roof.

Either way the balls seem like a solid approach.

How would you make a lake-sized tarp? How would you deploy it, repair tears, etc. You can just make balls with a press and dump some more if they get damaged.

I guess that the area to cover is very wide, and having a tarp that size can be expensive. And then you still have to manage it in order to tolerate the weight of rain water, leaves and sand that would eventually gather upon it.

I'm guessing the problem is managing a tarp that big.