I think the idea is that the hemp will/should move with the ice sheet and the vertical sheering takes place between the wood piling and the hemp. Sort of like placing a soft bushing between the piling and the ice slab. It is therefor important to wind the hemp rope well below and above any possible ice thickness or elevation on the piling.
My would be contractor wanted $1,100. to put in the 4 pilings. I'm still looking.
