Sorry erik, never used one. Had a mid 40" musky up through over 2' of ice one late February weekend. No gaff. Unhooked, pics and lives to fight another day. This is a regular discussion with my "old school" fishing buddy every year.
That said, there's a 40"+ pike in Fox Lake that "could" have been iced with a gaff.
As it was, she clamped down so hard on the bait I never moved hooks and on the third pass by the hole, turned on her side, opened her mouth and everything just lifted out as she went by. Auuuuggghhhhh! (channeling by best Charlie Brown).