Line handling and mooring

USCG Boatswain Manual Ch. 2 §2.1

Mooring and Anchoring Mooring lines (BCSM Ch. 10 §D.2.c, Figure 10-19): the bow line (#1) and stern line (#4) hold the vessel to the dock; the after bow spring (#2), which leads aft from the bow, and the forward quarter spring (#3), which leads forward from the quarter, keep the vessel from surging forward or aft. Normally only these four lines are needed; breast lines (#5), run at right angles to the dock, add holding strength in foul weather. Spring lines are named for the direction they lead from the boat — an after spring leads aft, a forward spring leads forward. Backing down against the forward quarter spring springs the bow out; going ahead against the after bow spring with the rudder toward the dock springs the stern out (§D.2.d).

USCG Boatswain Manual Ch. 3 §3.1

Towing Towing astern uses a tow line connected to the towing vessel's stern and the towed vessel's bow. The catenary (sag) of the tow line absorbs shock loads; longer tow lines increase shock absorption but reduce manoeuvrability.

USCG Boatswain Manual Ch. 3 §3.2

Towing Towing alongside (hip tow) connects the two vessels rigidly via bow, stern, and spring lines. Used for short-distance manoeuvring in calm water — not for open-water passages.

33 CFR §164.76

Towline and terminal gear for towing alongside and pushing ahead. The owner, master, or operator of each vessel towing alongside or pushing ahead shall ensure that the face wires, spring lines, and push gear used— (a) Are appropriate for the vessel's horsepower; (b) Are appropriate for the arrangement of the tow; (c) Are frequently inspected; and (d) Remain serviceable. [CGD 94-020, 61 FR 35075, July 3, 1996]

NAVEDTRA 14067 §3-2

Knots, bends, and hitches A knot is used to form an eye or to secure a line to itself; a bend joins two lines together; a hitch secures a line to a spar, ring, or another line. The essential AB repertoire and its uses: the square (reef) knot ties two lines of equal size together for light duty or secures a furled/lashed object, but it is not trusted for joining two lines under strain and jams under heavy load; the bowline forms a fixed, non-slipping eye in a line's end and is the workhorse knot for putting a loop over a bollard or around an object — it does not slip yet unties easily even after loading; the clove hitch secures a line to a spar or rail and is 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 t…

NAVEDTRA 14067 §4-1

Deck fittings and line-handling safety Deck fittings are the fixed points to which lines are led and made 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. 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 g…