Hello, My friend needs to transfer construction objects across a pond, came up with this idea of tying a rope between the pond and a big tree then transfer objects through a pulley, I'd like to know how to calculate the tension and will the thin concrete wall withstand the load? Here a diagram. http://i304.photobucket.com/albums/nn192/melodic27/pulley wall_zpshceuf5ah.jpg The crossing length is 20 meters, the starting point of rope is tied to a big tree, 0.5 meters higher than the point at destination. The person and rope in purple is to make sure the pulley does not move to faster than, to give a constant velocity of 1 meters per second. I also have no data of how much shear stress the wall can handle. If need clarification you are welcomed to ask. Thank you very much.