Minecraft wiki entry for Endless_circling_pool, associated text: Using the techniques described in Tutorials/Water-powered boat transportation, the smallest circling pool that can accommodate a boat has one solid block in the center and four quadrants of water flowing from one corner of each quadrant. This design requires a 7×7 area, 1 layer, 4 water source blocks ("S" in the schematic), and 8 buttons or signs — one on each side of the central block and one on the wall opposite each central sign or button.