Drilling Equipment

High Holding Power Anchor Development

Anchors for floating vessels have evolved from ancient times. The earliest anchors were stones that had holding power of less than their own weight. By the early 1900s the stockless anchor had been developed. That style anchor was, and still is, widely used on merchant and naval ships because it is easily stowed in the hawse pipe. The stockless anchor has a holding power of about twice its weight in air. In the late 1930s Richard S. Danforth and his nephew, Robert Danforth Ogg, developed the theory and designs for a light weight, drag embedment anchor. U.S. Patent 2,249,546 was granted to Richard S. Danforth on July 15, 1941. The Danforth anchor developed holding power of about ten times its weight in air and was widely used on landing craft during World War II.

The U.S. Navy built on Danforth's work and developed the STATO anchor with a holding power of about twenty times its weight. Mr. R.C. Towne, of the U.S. Naval Civil Engineering Laboratory at Port Hueneme, California, was instrumental in that effort and that organization published standardized test data on anchor holding powers that has been very useful to the offshore industry. In subsequent years numerous specialized, high holding power anchor designs have been developed for the offshore construction and drilling industries. These specialized anchors have holding powers of about twenty five times their weight and were a vital component in the large drilling and construction vessels for areas such as the Gulf of Mexico and the North Sea.

Some of the pioneers in these more recent developments are Peter Bruce, of Bruce Anchor Limited in the U.K.; Rob van den Haak, of Vryhof Ankers B.V. in the Netherlands; and Peter J. Klaren, of Anker Advies Bureau B.V. in the Netherlands.

Recognizing the pioneering efforts of the following individuals and companies who contributed to the development of this technology:

Richard Stevens Danforth, Robert Danforth Ogg, Richard C. Towne, Peter Bruce, Rob van den Haak, Peter J. Klaren

U.S. Naval Civil Engineering Laboratory, (Naval Facilities Engineering Service Center), Bruce Anchor Limited, Vryhof Ankers B.V., Anker Advies Bureau B.V. (Wortelboer Jr. B.V.)