It is not on a swivel. I redrilled holes next to the ones that were there, about an inch away and remounted the cleat when mine pulled out. You will not be able to go to the next size up unless you want to put larger cleats on...you do not.

If you spinnaker sheets tie together on the trampoline you could add a piece to see what length you want before committing to it. I use a spectra line with double eye splice in it about 15 inches long and mount that to the half way point on the spinnaker sheet. The other end gets looped into the spinnaker clew and the sheet goes through it to lock it on. Spin sheet stays with the chute when you put it away. Run the lines through the blocks and tie together. This way you can add some line and it should not effect the way it works providing you do not have a knot going to the lazy block making it too short. Easy to experiment with though.

Later,
Dan