Usually, folks will mark their anchor chain so they know how much chain has gone out. This is helpful for calculating scope. Scope is the length of anchor line relative to the distance from your boat's deck to the sea bottom. Geralyn and I usually do 3:1 for lunch or fishing and 7:1 or more for overnight anchoring. We've noticed our anchor has marks on it, but never knew the system that was used. This past week, we took all the chain onto the dock and documented the previous owner system for marking the anchor chain. We like the system, so we won't change it, just touch it up a bit so the marks can be seen more clearly. We keep a copy of the system posted in the cockpit and the bottom of the anchor locker door.
Here is the system:
w = white
y = yellow
g = green
o = orange
30 ft = W
60 ft = WW
90 ft = WWW
120 ft = Y
150 ft = YY
180 ft = YYY
210 ft = G
240 ft = GG
270 ft = GGG
300 ft = O
330 ft = OO
360 ft = OOO
390 ft = Long O
w = one white mark
ww = two white marks
www = three white marks
Primary Anchor - 35lb Delta G4 5/16 chain
Secondary Anchor - Fortress. 135 ft rope. 15 ft chain.