Depending on what part of the country your from a shack is a shanty and a shanty is a shack. I know here in Maine they are called shacks. A smelt shack has one or two long holes cut out in the floor, thus allowing each person fishing 5 smelt lines, the holes in the ice are cut with saws or a series of holes with an auger. My shack has two holes on each side with a bench in the middle and the holes are cut 5'Lx14"W.