>I use a pulley for each end of the boat and a cleat on the wall for each rope, and a "s" hook on the end of the rope. I also put a stop knot in the rope that hits the pulley when the boat is down at the right level to pick it up.<

Gary, this seems simple enough, but a little risky. What if you (or your kid) uncleats one end and lowers it without the other? Doesn't this invite the boat to slide nose-first out of the sling and crash onto the floor? Do you have a way of ensuring that the sling ropes work together? Also, it seems that if you put the boat in the sling when the loop is extended to its maximum size and then pull the rope through a pulley on one side only, the boat must then keep sliding toward the fixed side of the sling as you take it up (or in reality, the rope keeps sliding under the boat toward the pulley side as you raise it). Is this a problem (abrasion, or even rolling the boat over in the process of raising it)? Mike