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
So named due to its resemblance to a traditional agricultural plough. Many manufacturers produce a plough-style design, all based on or direct copies of the original CQR ("Secure"), a 1933 design patented in the UK (US patent in 1934) by mathematician Geoffrey Ingram Taylor. Ploughs are popular with cruising sailors and other private boaters. They are generally good in all bottoms, but not exceptional in any. The CQR design has a hinged shank. Despite the widely held belief that this is to allow the anchor to turn with direction changes rather than breaking out, the actual purpose is to prevent the weight of the shank from negatively impacting the fluke's orientation while setting. Other plough types have a rigid shank. Plough anchors are usually stowed in a roller at the bow.