Line handling and mooring: naming the lines and tending them under load

What the rule requires

The lines and the job each one does

Working forward to aft, the standard arrangement alongside is five kinds of line, and each has one job NAVEDTRA 14067 §4-2:

Head line — leads forward from the bow to the pier; holds the forward end in.
Stern line — leads aft from the stern; holds the after end in.
Breast line — leads nearly at right angles to the vessel; holds her bodily against or off the pier.
Forward (bow) spring — leads forward from aft; prevents the vessel moving astern.
After (stern) spring — leads aft from forward; prevents her moving ahead.

The same five appear as bow line, stern line, forward spring, after spring, and breast lines perpendicular to the dock at the beam USCG Boatswain Manual Ch. 2 §2.1. The two authorities label the springs from opposite ends of the line, which is dealt with below; the function of each never changes.

You are alongside and she is creeping ahead in the berth. Which line checks her?

The spring that leads aft — the after (stern) spring — prevents her moving ahead. Hardening up the head line will not do it, and neither will a breast line, which only holds her against or off the pier.</details>

Getting the line ashore

A heaving line — a light line weighted with a monkey's fist — is thrown to the pier and used to haul the mooring line's eye across, and the eye is then dropped over a bollard. The crew take the strain on the bitts or warping head and adjust the lines to position her .

Where your eye and another vessel's share one bollard, the second eye is passed up through the first — dip the eye — so that either can be let go independently. Fenders are placed to protect the hull, and chafing gear is fitted where a line bears on a chock.

Getting under way, lines are singled up, extra turns cast off leaving one part, and then let go in the order the maneuver requires.

The fittings, and making fast

Bitts are paired vertical posts, usually welded to the deck, around which mooring and towing lines are figure-eighted and secured; cleats are horn-shaped fittings for smaller lines; chocks are fairleads — open, closed, or roller — through which a line passes over the side, changing its lead without a sharp bend and protecting it from the deck edge; bollards are the shoreside posts a ship's eye is dropped over NAVEDTRA 14067 §4-1.

A line is made fast to bitts by taking a round turn on the after bitt, then figure-eights across both bitts, finished so it can be surged or slipped. To surge a line is to let it slip around the bitts or a warping head in a controlled way, taking the strain gradually.

The line under load

The greatest danger in line handling is the bight and the snap-back zone. A line under load stores energy, and if it parts, the ends whip back along the line's lead with lethal force. Hands never stand in the bight — inside a loop — never stand in line with a line under strain, and stay out of marked snap-back zones.

Where the load may surge, lines are tended, not cleated hard, so that they can be eased or slacked rather than parting. Keep the deck clear of stray turns, watch fingers around bitts and warping heads, and never step on a line that is running out.

The standard commands

These are fixed, and questions turn on the difference between two of them :

take a strain — put the load on the line.
heave around — haul in on the winch or capstan.
hold — stop it going out.
check — let it slip just enough to control the strain.
slack — ease it out.
let go — cast it off.

The vessel is still carrying way alongside and the mate calls "check the after spring." What is your action?

Let the line slip around the bitts or warping head just enough to control the strain — surging it in a controlled way while the load comes on. Not hold, which stops it going out altogether, and not slack, which eases it out and gives up the control you are trying to gain.</details>

Knots, bends, and hitches

The distinction is what the line is being secured to. A knot forms an eye or secures a line to itself; a bend joins two lines together; a hitch secures a line to a spar, ring, or another line NAVEDTRA 14067 §3-2.

Bowline — forms a fixed, non-slipping eye in a line's end; the workhorse for putting a loop over a bollard or around an object. It does not slip, yet unties easily even after loading.
Sheet (becket) bend — joins two lines, especially of unequal size, and holds better than a square knot.
Square (reef) knot — ties two lines of equal size for light duty, or secures a furled or lashed object. It is not trusted for joining two lines under strain and jams under heavy load.
Clove hitch — secures a line to a spar or rail, quick to make, but can work loose under a varying pull, so it is often backed with a half hitch.
Two half hitches — makes a line fast to a ring or post.
Rolling hitch — takes a strain along a spar or onto another taut line; this is the hitch used to stopper off a line under tension.
Figure-eight — a stopper knot to keep a line from running through a block.
Timber hitch — for hoisting or dragging a spar. Cat's paw — for hooking a line to a hook.

A good knot is easy to tie, holds under the load intended, and can be cast off when needed.

Springs made up for a hip tow

Towing alongside — the hip tow — connects the two vessels rigidly via bow, stern, and spring lines, and is used for short-distance maneuvering in calm water, not for open-water passages USCG Boatswain Manual Ch. 3 §3.2.

Once you are towing alongside or pushing ahead, the gear carries a regulatory duty. The owner, master, or operator shall ensure that the face wires, spring lines, and push gear used are appropriate for the vessel's horsepower, appropriate for the arrangement of the tow, frequently inspected, and remain serviceable 33 CFR §164.76.

Telling it apart

One criterion separates every line in the arrangement: the direction the line leads away from its fitting, and therefore the motion it checks.

Head line and stern line — lead forward from the bow and aft from the stern respectively, roughly along the berth; they hold the ends in NAVEDTRA 14067 §4-2. Most often misfiled as springs, because a head line and an after spring both lead away from the bow region.
Breast line — leads nearly at right angles to the vessel; holds her bodily against or off the pier. Misfiled whenever a question asks what stops her working fore and aft in the berth, which a breast line does not do.
Forward (bow) spring — leads forward from aft; prevents movement astern.
After (stern) spring — leads aft from forward; prevents movement ahead.

The convention trap is real and it is on your shelf. NAVEDTRA names the spring by the direction it leads — the line leading forward from aft is the forward (bow) spring — while the Boatswain Manual lists the forward spring as running aft from the bow USCG Boatswain Manual Ch. 2 §2.1. When a question describes a lead or shows one, decide from the lead and from the motion the line would check, then pick the option whose description matches. Do not decide from the name alone.

Working a question

You are bringing a vessel alongside a pier, port side to. The current is setting along the berth from ahead, carrying her aft as she loses way. Which line goes ashore first, and how is it handled?

Name the motion to be checked. She is being carried astern. The line that prevents movement astern is the spring leading forward — from a fitting aft, forward to the pier NAVEDTRA 14067 §4-2.
Reject the lines that cannot do it. A breast line holds her against or off the pier, however hard it is hove; a stern line holds the after end in. Neither arrests a vessel running aft along the berth.
Send it across. Heaving line with its monkey's fist to the pier, haul the eye over, drop it on the bollard. If the bollard already carries another eye, dip yours up through it so either can be let go independently.
Make fast to take the strain. Round turn on the after bitt, figure-eights across both bitts, finished so it can be surged or slipped NAVEDTRA 14067 §4-1.
Tend it as the load comes on. The load will surge as she settles, so the line is tended rather than cleated hard, and it is surged or checked to take the strain gradually. Hands stand clear of the bight and out of line with the lead.
Protect the lead. Chafing gear where the line bears in the chock, fenders down.
Then complete the arrangement. Head and stern lines to hold the ends in, the after spring against movement ahead, breast lines to hold her bodily alongside.

For a labelled-illustration question, the method is step 1 in reverse: trace the line from its fitting outward, establish which way it leads, and name it from that.

Where candidates lose the point

Naming a spring from the end it is made fast to. A candidate who has memorised "forward spring runs from the bow" will misname the line every time the question describes a line leading forward from aft, which NAVEDTRA calls the forward or bow spring. Work from the lead and the motion checked.
Expecting a breast line to stop her surging in the berth. It is attractive because a breast line is heavy and obviously important, but only the springs control fore-and-aft movement.
Choosing "hold" where the answer is "check." Both sound like stopping the line. hold stops it going out; check lets it slip just enough to control the strain. Holding a line the load is still building on is how a line parts.
Standing outside the loop and calling that clear. The bight is not the only danger area: if a line parts, the ends whip back along the line's lead, so a hand standing in line with a taut line is in the snap-back zone even with no loop near him.
Reaching for a square knot to join two mooring lines, or a heavy line to a lighter one. It is the knot everyone can tie. It is not trusted for joining two lines under strain and jams under heavy load; the sheet (becket) bend is the joining knot, and it holds better with unequal sizes NAVEDTRA 14067 §3-2.
Treating a hip tow as ordinary mooring work. Once you are towing alongside or pushing ahead, the face wires, spring lines, and push gear must be appropriate for the horsepower and for the arrangement of the tow, frequently inspected, and serviceable 33 CFR §164.76. The hip tow itself is for short-distance maneuvering in calm water, not an open-water passage.

Check yourself

You are moored port side to. A passing vessel's wake starts working you ahead and astern along the berth. Which lines are doing the work of holding you in position fore and aft?

The springs. The forward spring, leading forward, prevents movement astern; the after spring, leading aft, prevents movement ahead. Head and stern lines hold the ends in and breast lines hold her against or off the pier, but fore-and-aft control belongs to the springs NAVEDTRA 14067 §4-2.</details>

The bollard you have been told to use already has another vessel's eye on it. What do you do?

Dip the eye: pass your eye up through the eye already on the bollard before dropping it over. Either vessel can then let go independently, instead of one being trapped under the other's eye.</details>

You must bend a light messenger onto a much heavier line to haul it across. Which knot?

A sheet (becket) bend. It joins two lines, especially of unequal size, and holds better than a square knot. A square knot on lines of that mismatch is not trusted under strain and jams under load.</details>

A mooring line is under tension and you need to take the strain off it further along its length. What do you rig, and where do you stand?

A rolling hitch, which takes a strain along a spar or onto another taut line and is the hitch used to stopper off a line under tension. Stand clear of the bight and not in line with the loaded line; if it parts the ends whip back along its lead NAVEDTRA 14067 §4-1.</details>

You are made fast to bitts and the swell is causing the load to surge heavily. Is the line best turned up hard, or tended?

Tended. Where the load may surge, lines are tended rather than cleated hard, so they can be eased or slacked rather than parting, and the turns are finished so the line can be surged or slipped.</details>

You are making a vessel up alongside for a shift across a harbour, then continuing offshore. Is the hip tow rig good for both legs?

No. Towing alongside connects the vessels rigidly via bow, stern, and spring lines and is used for short-distance maneuvering in calm water, not for open-water passages USCG Boatswain Manual Ch. 3 §3.2.</details>

As master of a vessel pushing ahead, what are you required to ensure about the push gear and spring lines?

That they are appropriate for the vessel's horsepower, appropriate for the arrangement of the tow, frequently inspected, and remain serviceable. The duty sits on the owner, master, or operator 33 CFR §164.76.</details>