Anchoring and mooring operations

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. 2 §2.2

Mooring and Anchoring Anchor scope (BCSM Ch. 10 §H) is the ratio of rode paid out to the vertical distance from the bow chocks to the bottom — water depth plus the height of the chocks above the water. Enough rode is paid out for its lower end to form an angle of 8 degrees or less with the bottom, so the anchor digs in and holds. The manual's range is 5:1 to 7:1 in normal conditions and 10:1 for heavy weather; at 5:1, anchoring in 20 feet of water takes 100 feet of rode. Less scope lifts the rode off the bottom and reduces holding power.

USCG Boatswain Manual Ch. 2 §2.3

Mooring and Anchoring The Boat Crew Seamanship Manual describes one anchor in detail, the Danforth (Ch. 10 §H.5, Table 10-1): a lightweight anchor with the stock at the crown and two flukes that dig in and bury, giving high holding power for its weight in sand and mud. Holding depends on the bottom: sand, clay and firm mud hold well; rock and coral hold poorly unless the anchor hooks a crevice; grass and weed often keep an anchor from digging in and give questionable holding for most anchor types (§H.11).

33 CFR §164.19

Requirements for vessels at anchor. The master or person in charge of each vessel that is anchored shall ensure that: (a) A proper anchor watch is maintained; (b) Procedures are followed to detect a dragging anchor; and (c) Whenever weather, tide, or current conditions are likely to cause the vessel's anchor to drag, action is taken to ensure the safety of the vessel, structures, and other vessels, such as being ready to veer chain, let go a second anchor, or get underway using the vessel's own propulsion or tug assistance. [CGD 74-77, 42 FR 5956, Jan. 31, 1977]

NAVEDTRA 14067 §4-2

Mooring lines and making the ship fast A ship is moored alongside by a set of lines that each do a specific job. Working forward to aft, the standard mooring arrangement is: head lines (lead forward from the bow to the pier) and stern lines (lead aft from the stern) hold the ends in; breast lines (lead nearly at right angles to the ship) hold her bodily against or off the pier; and spring lines control fore-and-aft movement — a forward (bow) spring leads forward from aft and prevents the ship moving astern, an after (stern) spring leads aft from forward and prevents her moving ahead. To send a 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, which is then dropped over a bollard; the ship's crew t…

NAVEDTRA 14067 §4-3

Ground tackle and anchoring from the deck Ground tackle is the anchor, chain, and associated gear a ship uses to anchor. On the forecastle the chain leads from the chain locker up through the spurling pipe, over the wildcat of the anchor windlass, through the hawsepipe, and out to the stockless anchor stowed in the hawsepipe. Holding the anchor and chain when not heaving are the brake on the wildcat and, more securely, a chain stopper — a pelican hook or riding pawl that takes the strain off the windlass while the ship rides to her anchor. Anchor chain is made up in shots (15 fathoms, 90 feet, each), joined by detachable links, and marked by a paint-and-wire color code at each shot so the crew can call how much chain is out as it runs. Anchoring: with the anchor walked out clear of the ha…