Longship
Longships for the most part used two different kinds of anchors. The most common was a natural wood yoke formed from a tree branch. The weight was supplied by a stone passing laterally through the U of the yoke. The top of the yoke was closed by either a length of hardwood or a curved iron head, which kept the stone in place. One side of the head stuck out so it could dig into mud or sand. In the Ladby ship burial in Denmark, a unique iron anchor has been found, resembling the modern fisherman's anchor but without the crossbar. The cross bar may have rusted away. This anchor—made of Norwegian iron—has a long iron chain to which the hemp warp was attached. This construction has several advantages when anchored in deep waters or in rough seas.
Anchor
The Fortress is an American aluminum alloy Danforth variant which can be disassembled for storage and it features an adjustable 32° and 45° shank/fluke angle to improve holding capability in common sea bottoms such as hard sand and soft mud. This anchor performed well in a 1989 US Naval Sea Systems Command (NAVSEA) test. and in an August 2014 holding power test that was conducted in the soft mud bottoms of the Chesapeake Bay.