The phrase "boat anchor" is used to describe something that is heavy, useless, or burdensome, like an anchor for a boat. It refers to a person, object, or idea that is holding you back or weighing you down. Full definition
There is a beach but the beach is not suitable for swimming because it is too shallow and there are a number of boats anchored in the area. (philippinestravelpackage.com)
People on board the 50 or so boats anchored around us drink beers and dance to classic rock. (sbnation.com)
I just had time for a cup of coffee before the speedboat took us to our dive boat anchored at Koh Bon. (dive-the-world.com)