IACS regulation regarding anchors

A1.1 Design of the anchoring equipment (1981)
A1.1.1 The anchoring equipment required herewith is intended for temporary mooring of a vessel within a harbour or sheltered area when the vessel is awaiting berth, tide, etc.
A1.1.2 The equipment is therefore not designed to hold a ship off fully exposed coasts in rough weather or to stop a ship which is moving or drifting. In this condition the loads on the anchoring equipment increase to such a degree that its components may be damaged or lost owing to the high energy forces generated, particularly in large ships.
A1.1.3 The anchoring equipment presently required herewith is designed to hold a ship in good holding ground in conditions such as to avoid dragging of the anchor. In poor holding ground the holding power of the anchors will be significantly reduced.
A1.1.4 The Equipment Numeral (EN) formula for anchoring equipment required here under is based on an assumed current speed of 2.5 m/sec, wind speed of 25 m/sec and a scope of chain cable between 6 and 10, the scope being the ratio between length of chain paid out and water depth.
A1.1.5 It is assumed that under normal circumstances a ship will use only one bow anchor and chain cable at a time.
A1.1.6 Manufacture of anchors and anchor chain cables is to be in accordance with UR W29 and UR W18.
A1.2 Equipment number and anchoring equipment table (for vessels of unrestricted service) (1981) (1999)
The equipment of anchors and chain cables is to be as given in Table 1 and is to be based on an “Equipment Number” calculated as follows:
Where:
∆ = moulded displacements, in tonnes, to the Summer Load Waterline
B = moulded breadth, in metres
h = effective height, in metres, from the Summer Load Waterline to the top of the uppermost house; for the lowest tier “h” is to be measured at centerline from the upper deck or from a notional deck line where there is local discontinuity in the upper deck.
Where:
a = distance, in metres, from the Summer Load Waterline amidships to the upper deck hi = height, in metres, on the centerline of each tier of houses having a breadth greater than B/4
A1 (1981) (Rev. 1 1987) (Rev. 2 1992) (Rev. 3 1994) (Rev. 4 Aug. 1999) (Rev.5 June 2005)
IACS Req. 1981/Rev.5 2005
EN = ∆2/3 + 2,0 hB  +  A 10
h = a + Σhi
Note: Rev.5 of this UR is to be uniformly implemented by IACS Societies on anchors and anchor chain cables the manufacturing of which is commenced on or after 1 January 2007.