Dragging an anchor is never a good thing. It means you either have the improper anchor, scope or bottom to effectively anchor.

Are you asking about a drogue anchor, which is like an underwater parachute? It is "dragged" behind a vessel to either slow up or stabilize the maneuverability of a boat.

Pick a reference point on shore to gauge if you are dragging!

The turning radius of a vessel is a mathematical computation used to determine the turning circle of the vessel during anchoring in order to check if the anchor is dragging. It can be computed by adding the length of the anchor chain to the overall length of the vessel and subtracting the length between bridge and aft.

it is determined by the length of the shackle passed into water,in addition to the length from the for'd perpendicular to the bridge.sum of these two are known as the swinging circle of the ship.it is radius at which the ship rotates with anchor as the centre.the radius will not exceed the sum of the lengths.it is important to check time to time whether the anchor is dragging or not.swinging circle should be closely watched when the ship's are nearby.swinging circle can be reduced by standing moor.