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.
Offshore embedded anchors
Anchor piles are hollow steel pipes that are either driven or drilled and grouted into the seabed, similar to pile foundations commonly used in offshore fixed structures. The figure shows the different installation methods whereby the driven steel tube is driven mechanically by a driving hammer, whilst the cast in-situ grouted pile is inserted into an oversize borehole constructed from a rotary drill and subsequently grouted in cement. Both methods are commonly used offshore depending on the geophysical and geotechnical properties of the seabed.