No one posted this problem but I always found it very annoying when I am having my main sail repaired. The foil bangs around in the mast.
To alleviate this noise I finally came up with a good solution.
I lower the swivel to the bottom and run the largest diameter line that will fit into the swivel.
I then raise the swivel to the top of the mast and rotate the foil while standing as far from the mast as possible. The line wraps around the foil making a bumper sort of arrangement.
