A good, old-fashioned tree swing. The seat is red oak, assembled with carpenter's glue and wood screws (with predrilled holes: it's very hard even as oak goes!). Since it goes outdoors, I cheated on the finish, multiple coats of polyurethane.It has battens at each end and a lengthwise "rib," which makes it very sturdy. The 5/16" U-bolts (with fender washers and spring lockwashers) probably should be 3/8" or even 1/2" instead, but they'll do for now. They are the better grade, at least: check carefully and you'll discover some U-bolts are marked with a warning to not use them to support weight!
Most of the smoothing was done with planes and a scraper. It looks great but the seat is almost too smooth.
The knots are not as awful as they look; hidden in there are bowlines-on-a-bight at each side, with a series of clumsy hitches around them to take up the free end of each rope.
This project required a
* And a nod to Charles for catching my typo.