I volunteer on the 50 foot historic tug at South Street Seaport in NYC. We chain it to the "dock" (actually a barge held in place by pilings). And no, not because it's NYC and we think someone is going to steal it. The wave action around lower Manhattan is so bad that even the 2 inch lines stretch overnight and the tug was getting "beat up".
When we get past the Covid crisis we'll probably resume giving rides in NY harbor if anyone wants a 1930 tugboat experience. It was originally steam powered, but now it has a DD 6 110.
The picture was taken in Albany NY on the way to the Waterford NY tugboat roundup last year. No chains needed since the Hudson was calm up there.