When another boat had it’s anchor down and could not get the anchor up, we would use our huge shackle to deanchor the other boat. Say the boat set it’s anchor while heading north and could not retrieve it. We would have them shorten the anchor rode as much as possible. We would put the shackle around the anchor rode with a tow line attached to the shackle. We would then drop the shackle down the anchor rode of the disabled boat. The shackle would drop down to the crown of the stuck anchor. When we had it worked all the way down, we would begin towing the disabled boat to the north and pull the anchor up. We could usually get the anchor to surface while towing it. The caution while doing this procedure is that if you do not get the shackle all the way down to the crown of the anchor it would ride back up the anchor rode to the disabled boat and smash into the bow. People would tend to try and grab the shackle before it would hit the boat and then they would get their fingers smashed or cut off.