As many have seen NY requires schackles and thimbles. Here in Texas we
require chain and shackles year around. Or harbor master requires each
boat to have two set of spring chains on each side of the vessel and a
min of 4 main docking chains.

The harbor manager has a robot chain bugs that inspects all the chains
on an automated bases. And your chains better be up to par or you are
outta here.

Ever seen a chain bug? http://www.twi.co.uk/j32k/twiimages/crks1f1.jpg

Joe