how/when are docking lines secured on a large/commerical ship?

In every video I’ve seen of large ships docking, the line* they toss/pass to the dockside personnel simply has a loop spliced into it. How and when is that line secured shipside? Youtube is not much help (all their videos are from dockside, and, usually, far away).

I assume the length between ship and dockside anchor points is going to vary with every port (and, depending on the port, with the tides), so there’s got to be some sort of adjustment shipside.

I’m familiar with small (~30-60’) boat tying up procedures (using cleats, never felt comfortable with rails), but those lines are much smaller, easily manipulated by hand, and usually secured to a floating dock (so tides aren’t an issue).

*actually, the line they toss is a lightweight messenger line that’s tied to the actual docking line (could you imagine trying to toss one of those >1" monsters?!)

The loop in the docking line is secured over a bollard.

The cruise ships I’ve been on seemed to have this line directly wound around a (huge) winch, so that once the end was attached to a bollard, the ship could pull itself slowly to the dock. That’s been my impression, anyway.

On the ship I was on (a destroyer), mooring lines were belayed to bitts (each consisting of a pair short, fat metal posts, about a foot apart).

It was easy to un-belay a line, adjust its length, then re-belay. Mooring lines were nylon, about 2" in diameter - and thus reasonably easy for one man to handle.

I’ve seen the thing you’re talking about on ferries and such. So, when is the line drawn taut and secured?* How often did you have to adjust the mooring lines (with the tides) when you were tied up to a non-floating pier/dock?
*With boats small enough for a single person to manhandle you’ll often use the mooring lines to actually draw the vessel into it’s final position. Something I you couldn’t really do with those big boys. Though I do recall seeing (in some documentary or other) special trucks that apparently could haul the big ships along the dock a short ways (i.e. a few yards/meters).

Once the ship is in its correct moored position, to the Captain’s satisfaction.

The lines are not especially tight - about as much tension as a couple of sailors can apply. You’re not trying to hold the ship rigidly in place.

Few of the places we visited had enough tidal range to be a problem. I’d guess that you’d need at least 6’ of tide before you’d need to worry about adjusting lines, and we rarely saw that.

If you do need to do this, it’s probably twice per tidal cycle - and most locations have 2 tides a day.

Actually, you can. “Spring ahead on 2” was a saying, which means use the #2 line (belayed) plus some engine thrust to draw the ship in toward the pier.

And though it sounds improbable, you can move a ship (at least a small one - ours was ~400’ long and 3000 tons) with muscle power alone: Get three or four strong guys pulling hard on the right line and the ship will move (real slowly). To be sure, only a little adverse wind or current makes this impossible.

What **Heracles **said at least as far as line handling is concerned. The mooring lines come off large winches, and are lead through fairleads in the bulwarks and then down to the bollards on the wharf.

As to tides, a key duty of the crew and officer of the watch when in port is to adjust the lines to account for tides, by letting line in or out as required, using the winches.

One point on which I would differ from **Heracles **is that lines aren’t used too much for pulling a large ship into the berth: this is mostly done using tugs and/or thrusters. The forces involved are too large for lines. What works on a titchy little destroyer doesn’t work on a hundred thousand tonnes of bulker or tanker.

This pagehas a picture of the foredeck of a ship showing lines and winches, near the bottom