Mooring Lines

Often called dock lines on smaller vessels, the term mooring lines is synonymous. The captain can only maneuver the vessel so much; ultimately the vessel will be controlled by the lines attached to shore. Effective coordination between captain and crew are critical, as poorly executed line handling can sunder an otherwise spectacular docking attempt.

Mooring Hardware

Bollard – a metal object on the pier resembling a tree stump and made to receive mooring lines.

Bitt – a bollard onboard ship. Often found in pairs and referred to as “bitts.”

Cleat – two horns around which figure eights are made followed by a half hitch.

Chock – a deck casting fitted at the side of a weather deck, used as a fairlead and provides an opening through the bulwark. Because of the hard bend of the mooring line at the chock, when a line parts it generally parts here.

Heaving line – a light line, which is tied to a heavier mooring line, which is more easily thrown to shore. It has a weight attached to the end of it, typically a monkey’s fist knotted around a lead ball.

Mooring Line Names

Typical mooring plan.

A – offshore stern line.
B – inshore stern line.
C – breast line.
D – forward leading spring line.
E – after leading spring line.
F – breast line.
G – inshore bow line.
H – offshore bow line.

Bow lines hold the bow in, stern lines hold the stern in. The primary purpose of spring lines is to stop the fore-and-aft movement of the vessel; if you cross the spring lines to make them as long as possible, they will hold the vessel to the dock even with great tidal fluctuations. Breast lines hold the vessel to the dock and run perpendicular to the vessel’s fore-aft line.

After dock lines are tied off, they should have chafing gear applied to any points of chafe, notably around the chocks or where lines cross. This should be done in preparation for storms, heavy weather, or in circumstances involving wave action.

Mooring lines, along with any line in use, should be occasionally end-for-ended to move points of chafe and wear. This is the act of re-tying the line using the opposite end.

Securing to Bitts

When using synthetic line two round turns should be taken on the bitt closest the strain, followed by figure eights across both bitts. This will give you the most control of the line and allow easy adjustment while maintaining that control. When using wire rope, because of its reduced flexibility, three full turns should be taken around both bitts before beginning figure eights.

Dipping the Eye

When placing a mooring line on a bollard that is already busy with a separate mooring line, it is best to bring the eye of the second line up through the eye of the first, and then place it on the bollard. This is known as “dipping the eye” and enables either line to be removed without having to remove the second line.

Line Handling Commands

Ease / slack – means to let the line out. Keep some dip, called catenary, visible in the line so the captain can see that the line isn’t controlling the vessel.

Check / surge – let the line out but maintain control of the vessel, the line is under tension. Keep control by one or more turns around the working bit or cleat. Under high amounts of tension, the line may melt to this fixture if surged too quickly. Polypropylene will melt first, followed by nylon, then dacron.

Take up – haul in a line and be ready to keep turns on the fixture so as not to lose any progress.

Hold / turns – take turns on the fixture and do not allow the line to pay out.

Make fast / belay – take turns and tie off the line.

Double up – place a second line on the same fixture on the shore. Both lines must be of equal length in order to be effective.

Single up – remove any doubled up lines down to the basic mooring plan. Usually in preparation for leaving the dock.