We have done a couple of 16 footers that probably would have busted the sides by rolling over, so we made this to help.
We happen to have a couple of trees just far enough apart to back the trailer between them, lift with come alongs, spin the boat over and lower back on trailer with supports (blocks of Styro foam worked best).
So far the center weight of the boats have been this thing mounted in the lower motor bolt holes and using the front bow eye.
Like Skools said, they are fairly easy to roll over, LOTS more energy to roll it back in place.