I anchor in about 30...to 60 feet of water...that's alot of rope
Holy CARP.I only do saltwater so I may way off base. That sounds like a very heavy anchor but if that's what you got use it. Pulling on it should be a days workout. The rule of thumb I was told at the coast guard class I took recommends 1 1/2 times the boat length of chain.
I anchor in the river during tide change. With the proper scope and proper anchor, you won't move. You only need a 13# danforth anchor and appropriate chain. You do not need 40# of anchorI anchor in the tidal portion of the fraser river so on an outgoing it gets going pretty good