I really don't know if cranes are used for this purpose at all, actually. Originally in my one minute of brainstorming before my five minutes of writing, I thought of a sentence like, "small paper planes dotted the ocean around her," but I couldn't think of a reason why you would put paper planes in water, especially the ocean. I thought that cranes were probably appropriate for that, and I thought it would be nice to put candles in them, but the density would certainly sink them, so I had to make them large cranes. Anyway, the whole thing still might make no sense, in terms of physics and in terms of purpose. But thank heavens for poetic license and allowing me to have such an indulgence as writing things that are completely unrealistic!