Ayelet Miller's research while affiliated with University of Haifa and other places

The force required to drag a stone anchor over several types of surfaces was measured, recorded, and analyzed. It was found that the force involved in the movement of the anchor over the various surfaces cannot be described just by the sliding solids theory, but it involves several additional physical processes, such as increasing the sand shear strength by the pressure the anchor applies on the sand under it; the sinking of the anchor into the saturated sand; shearing the sand in front of the moving anchor and accelerating it to the velocity of the anchor; accumulating sand in front of the anchor, thus adding to the pulled mass; and moving some of the accumulated sand sideways. In many instances, the beginning of the anchor movement involves the liquefaction of the sand under it, thus enabling the relatively easier sliding of the anchor. In addition, movement over rocky surfaces, encountering the irregularities that abound on such surfaces, also differs from classic sliding friction theory. In several situations, the use of an effective coefficient of friction, combining all the processes, can serve to obtain approximate values of the required forces.

Many one-hole stone anchors have been found around the eastern Mediterranean, in Kaş (Uluburun, Gelidonia), Antalya, Ugarit, Byblos, Kition, the Carmel coast, Caesarea, Ashkelon, Alexandria, etc. They are of varying sizes, weighing from a few to hundreds of kilograms. Apart from the single hole, they have another common attribute – they all fell within a certain range of geometrical proportions, one of which was the length to thickness ratio of about 4.2:1. The hole in the upper part of such an anchor increases the susceptibility of the anchor to mechanical failure. Sensitivity to three major modes of failure – tension, shear and bending, was analysed. It was found most broken anchors seem to have failed by bending. Such failure could be incurred either during service life on a ship or in secondary use on land. It was also found that for three-hole composite anchors, the average length to thickness ratio was about 5.5:1, meaning that for a given face area they were relatively thinner and lighter. In addition, they were smaller in face area, and thus had about 25%–50% greater holding power, and posed less handling risk to ship and crew than the one-hole type.