I agree with Thinwater. The chain weight drags down the shank into the mud. The flukes will eventually dig in due to gravity, but certainly not so much from their wimpy weight. If the shank buries from the weight of the chain, eventually it will reach the extreme of its travel and force the flukes in.thinwater: I do not agree with the idea that soft mud would reduce an anchor set as it would drag the blades down with it. This could help an aluminum "danforth" more than hinder. If a Fortress aluminum anchor is any good just think how much better it would be made of 25 lbs of steel and 25' of chain! Chief