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 bolt
The force-transfer mechanism is based on bond stresses provided by binding organic materials. Both Ribbed bars and threaded rods can be used and a change of the local bond mechanism can be appreciated experimentally. In ribbed bars the resistance is prevalently due to shear behavior of concrete between the ribs whereas for threaded rods friction prevails.(see also Anchorage in reinforced concrete). Bonded anchors are also referred as "adhesive anchors". The anchoring material is an adhesive (also called "mortar") usually consisting of epoxy, polyester, or vinylester resins. The performance of this anchor's types in terms of 'load-bearing capacity', especially under tension loads, is strictly related to the cleaning condition of the hole. Experimental results showed that the reduction of the capacity is up to 60%. The same applies also for moisture condition of concrete, for wet concrete the reduction is of 20% using polyester resin. Other issues are represented by high temperature behavior and creep response.