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A true ice anchor that won't ever let you down is made thus: Cut pieces of 2"x2" (2"x4" or whatever) wood that are wider than your holes. Get a 3' piece of (nylon)rope. Drill a hole in the wood to accomodate the diameter of the rope. Pass an end of the rope through the hole and tie it off. Go fishing. Drill a hole. Push the piece of wood lengthwise down the hole, and then turn it horizonal under the ice. You should now have a piece of rope that comes up through the ice that you can tie off to, that is attached to a piece of wood that is wedged under the ice. The hole will freeze which means that you will have to cut the rope (cut it as short as possible, so you aren't leaving extra on the ice). Cheap, one-time use, no fail. You don't need these for all your tie off points. Just the crucial ones. Use ice screws for the rest. I usually make a batch of these and keep two in the sled for those real bad days.
I think this idea is simmiliar to what Gamedog does with PVC pipe except I think he retrieves his completely and it can be reused...
lol...you better have a Shaquille Oneill wingspan to do that in Iowa.....30" of ice...almost need an extension.
Never happened yet If you can get a tip-up out after being out overnite, these are no different.