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 best rope for warps is nylon which is strong and flexible. Terylene (polyester) is stronger but has less flex. Both ropes sink, so they avoid fouling other craft in crowded anchorages and do not absorb much water. Neither breaks down quickly in sunlight. Polypropylene or polythene are not suited to warps as they float and are much weaker than nylon and only slightly stronger than natural fibres. They break down in sunlight. Natural fibres such as manila or hemp are still used in developing nations but absorb much water, are relatively weak and rot. They do give good grip and are often very cheap. All anchors should have chain at least equal to the boat's length. Some skippers prefer an all chain warp for added security in coral waters. Boats less than 8 m typically use 6 mm galvanized chain. 8–14 m craft use 9 mm chain and over 14 m use 12 mm chain. The chain should be shackled to the warp through a steel eye or spliced to the chain using a chain splice. The shackle pin should be securely wired. Either galvanized or stainless steel is suitable for eyes and shackles.