Hanging A Hammock On Deck Beams

I am trying to put up some sort of anchors on the beams above my balcony to suspend a hammock. The hammock is 9.5 feet long with S hooks on each end. It also has nylon rope to use with the S hooks that are supposed to wrap around trees. The deck is 13 X 7.5 and the the beams are about 8.5 feet off the ground.

I am trying minimalize the amount of screwing/drilling I have to. There are a few pictures in this album below of the beams/deck. Any help would be greatly appreciated.

http://imgur.com/a/WNjDp