Abstract
The present paper gives the results of full-scale trials on one of ship bower anchor which were carried out on board the training ship "SHIOJI MARU". The tests were conducted on JIS-type anchor in general use in Japan to-day, and the tensions on chain were measured by means of wire strain guages while the ship's engine was being reversed. The types of sea bed in these trials were mud and sand. From the results of the tests, the authers have come to the following qualitative conclusions. (1) The holding power is found out to be superior in sand to in mud. (2) The rotational instability is not observable. (3) It is desired to drop anchor as slowly as possible in case the bottom is soft. (4) It is most desirable to use sufficient scope of chain, the amount of which is to be determined by taking the depth of water into consideration. (5) The ship can be best held when the anchor is brought up firmly. It is, however, rather difficult at times to determine when the anchor bites into the bottom. (6) When the ship begins to drag the anchor along the bottom, the pull on the chain falls to approximate constant value to be determined by the type of the bottom. (7) It is reasonable to define the so-called holding power of an anchor as the maximum pull on chain which will be reached just before the moment the anchor begins to drag.
