Thanks John!
I came across the idea reading the Wayfarer Institute of Technology PDF and was curious, perhaps its old info.
“As the mast bends, the foot travels aft along the channel. This travel can be
limited by a bolt through the U channel. The amount of travel to allow is controversial. Currently,
I allow a max. of about 3,8 cm (1½”) of movement at the foot of the mast.”