The Germanisher Lloyd recommendation is

Displacement up to 2 tons: 1st anchor 10,5 kg,  2nd anchor 9,0kg
3 tons: 12,0 10,0
5 tons: 13,5 11,0
8 tons: 17,0 15,0
12 tons: 21,0 18,0
17 tons: 25,0 21,0
23 tons: 29,0 25,0
29 tons: 34,5 29,0
36 tons: 40,0 34,0
44 tons: 46,5 40,0
52 tons: 53,0 45,0
57 tons: 62,0 53,0
72 tons: 73,5 62,0
100 tons: 95,0 81,0


These weights are for High Holding Power anchors as BRIC, FAST, M, ROCNA, WING and plough anchor. When using fisherman or weight anchors multiply with 1,33.

However, for boats falling under ES-TRIN, 20m+ or LxBxD>100cum, the requirement a about double these figures. This is being challenged