Full Anchor Chain?

[UNCIVILIZED]

For a boat your size, I'd say 5/16" HT. Preferably half a barrel or so, AKA 275', backed up with at least 100' of your favorite type of rope rode. Minimum strength around 15k (wet that is).
If you hunt, you can find the chain for just a bit over $2/ft. And at that size, you're looking at about 1.1lbs/ft, so #300, plus the rope rode & windlass.

[Terra Nova]

Yeah, 300' of 5/16" HT should do it.

TN's is overkill, 270' of 3/8 HT on a 24,000 lb boat.