Rusty anch or chain.
 

http://webriggingsupply.com/pages/ca...catalog.html#A

You can get 316 stainless 3/8 chain for 20 bucks a foot. Galvanized
proof coil is the same strength for 1.90 a foot. Unplated high test is
2.10 and twice as strong as either. I had to check. Those people also
have every imaginable cable.

Guy named Roebling invented wire rope and his son built the Brooklyn
Bridge. He had his own wire factory, which later did the wire for the
Golden Gate. They are still in business. They have cable with three
sizes of wire. Rounder, with less air space. The software is ****ing
with me or I would provide a link.

Casady