A connecting device for lengths of chain, usually of D or bow shape, having a removable pin through eyes at the open end.
The pin, called a shackle pin, may be screwed, clenched or secured by a forelock or split key. The terms screw shackle and clenched shackle apply to the corresponding cases.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
diameter at the waterline (m)
change in the value of a term
Solar declination angle (in degrees)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM