Wow..that's something else! Looks to my (unprofessioal) eye like overthick gelcoat and cold weather contraction/expansion issues between the gelcoat and the laminate. Nasty.
While not a Hunter fan overall, I've certainly never seen anything this extreme on the larger boats.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)