ONDECK
Academy
OOW Oral Prep
Module 22 — OOW 3000 GT Oral Preparation
Anchoring, Mooring & Yacht Operations
The anchoring evolution · Anchor watch & dragging · Mooring lines & snap-back · Med mooring · Berthing in wind · Tender & helicopter operations
The Anchoring Evolution — Start to Brought Up

Anchoring is an evolution with a sequence, and the oral expects you to talk it through as one. Approach head to wind or tide — whichever governs — and stop the vessel over the intended spot. In depths beyond about 15–20m, walk the anchor back on the gypsy to near the seabed rather than letting go from the hawse: free-falling in deep water risks a runaway cable, brake damage, and a heap of chain piled foul on top of the anchor. Then come dead slow astern, veering as she gathers sternway, so the cable lays out along the seabed pointing at the anchor.

Why the lay matters: an anchor holds because the pull on it is horizontal. The catenary — the sag of the chain — is both the shock absorber and the guarantee of a horizontal pull at the anchor. Chain piled on the anchor, or a short stay up-and-down, gives neither.
ItemWorking figuresNotes
Scope — chain4–6 × depthMore for weather. "Depth" is to the hawse — add the freeboard.
Scope — rope/chain mix6–8 × depthLess catenary from rope; more scope buys the horizontal pull.
Walk back vs let goWalk back beyond ~15–20mLet go acceptable in shallow water with the brake controlled.
Brought upCable snatches taut, then eases to a steady light leadConfirmed by anchor bearings/transit taken immediately, GPS ring set.

Log the position, depth, scope and bridge marks. The evolution is not finished until the anchor watch is set up to detect a drag — which is a planning act, not a hope.

Choosing the Anchorage
CheckWhat you are actually asking
ShelterAgainst the FORECAST including its veer — tonight's northerly matters more than this evening's calm. Steep coastlines add katabatic risk on clear nights.
Holding groundChart abbreviations: sand (S) and mud (M) good; weed (Wd), rock (R), coral poor. Weed over sand fools both the anchor and the echo sounder.
Depth bandEnough water at LW for draught + UKC; shallow enough that full scope is practical. Deep anchorages silently halve your scope.
Swinging roomFull-scope circle clear of dangers AND of the neighbours' circles at a wind shift.
RestrictionsCables, pipelines, prohibited areas — and in the Med, protected posidonia seagrass: charted, enforced, fined.
Escape routeAn exit you could steer half-asleep at 0300 if the weather turns. Name your bolt-hole before you need it.
Anchor Watch & Dragging

An anchor watch is a navigational watch — STCW says so. The content: position verified continuously against prepared references — anchor bearings and a transit on fixed shore objects (instant and power-free), a GPS anchor ring sized to the true swinging circle (scope + LOA), radar ranges to fixed points — plus the cable's behaviour, the weather TREND, and the neighbours' circles. Escalation triggers are briefed: at what wind, at what position change, the master is called.

Detecting the drag: a cable that leads taut, snatches, and vibrates underfoot is an anchor breaking out and re-biting. Transits move. The GPS ring alarms — if it was sized correctly. The vessel's yaw pattern changes character.

Response ladder once dragging: master called; engines started and used to ease the load — steaming gently up toward the anchor cuts the cable tension and can save the hold; veer more scope if room allows; then the real decision, made early — re-anchor with better scope and holding, or weigh and put to sea. A dark, crowded roadstead in a gale is often more dangerous than open water. A second anchor is a plan (fouling risk, doubled recovery), never a reflex. Rule 30 lights/shapes and Rule 35 fog signals remain correct throughout.

The neighbour dragging down on you is your emergency too: self-check your own hold first (whatever broke hers is under your anchor), plot her drift line against your circle, hail her, and be ready to sheer clear on your cable, veer to drop back, or weigh. Crew clear of foredeck snap-back zones in case she picks up your cable.
Mooring Lines — Functions and the Snap-Back Discipline
LineLeadsControls
Head / stern linesForward / aft from the endsThe ends, a blend of alongside and off-the-berth
Breast linesSquare off the hullDistance off the berth
SpringsAlong the berth (fore spring leads aft, aft spring leads forward)Surging — motion ALONG the berth. The uncredited workhorses.

Springs also do the handling work: slow ahead against a fore spring with helm toward the quay levers the stern off — the standard single-screw departure with onshore wind (fenders at the pivot). Lines are tended for tide, chafing gear rigged, and load shared deliberately as wind builds — a line eased at 50% never parts at 110%.

Snap-back kills. A tensioned line that parts recoils along and AROUND its leads at lethal speed — the danger zone maps the line's path through every fairlead, not just its straight run. Nobody stands in a bight or a recoil path; worn line is retired; winch brakes are tested; and the whole party is briefed on where not to be before the first line goes ashore. This is COSWP territory, and on a yacht with guests on deck the stakes double.
Mediterranean (Stern-To) Mooring

Med mooring is an anchoring problem wearing a berthing costume: the anchor and cable are the entire off-the-quay force. Geometry first — the anchor laid 3–4+ boat lengths out, dropped up-wind of the slot's centreline in any crosswind. Back down under control laying cable — sternway puts the pivot point aft, so the BOW is the wide-swinging end and the thruster earns its keep holding it up-wind; the cable, snubbed judiciously, is a steerable brake. Stern lines ashore both quarters, then tension cable against stern lines to hold her off the wall, passerelle gap set.

Classic failureCausePrevention
Crossed anchorsDrop point too close or too square to the neighbours' cablesDrop inside your own slot's projection; clear a foul by dipping under with a line, never winching blind
Stern kisses the quay at 0200Short scope — nothing holding her off when the surge sets inScope laid properly on the approach; re-tension before turning in
Lazy line in the propellerMarina ground tackle picked up under wayKnow the system before entering the slot; lines tended, engines clear
Berthing in Wind
Onshore wind — the free berth with a trap

The wind lays you alongside for nothing; the risk is arriving too fast and being pinned. Approach FLAT and slow, park a beam-width off, and let the wind do the last metre under control — fenders ready, lines fast smartly. Plan the departure before you arrive: springing off stern-first, thruster, or a tug.

Offshore wind — the fight

High-windage bows blow off the moment way comes off. Come in steeper carrying way, first line ashore FAST (fore spring or head line), and work her alongside against lines and thruster. Know your honest wind limit — above it, the answer is a tug or a different plan, and saying so is seamanship, not weakness.

Thruster honesty: effective essentially at rest to ~2–3 knots, weak into a strong beam wind, thermally limited on sustained runs, and dependent on the electrical plant. Plan the berthing to work with helm, engines and lines alone — the thruster polishes the last metres. A plan that REQUIRES the thruster fails the day the breaker trips.
Tender Operations — The Yacht's Daily Seamanship

The tender is where a yacht OOW's COLREGS, load line and safety knowledge gets exercised daily — and where the MCA examiner knows yacht candidates actually live.

AreaStandard
Before launchFuel, oil, hull, kill cord tested, nav lights, comms (VHF + means of recall), bungs confirmed IN — physically, hands-on
LoadingWithin the tender's plate capacity — persons AND weight; trim managed; guests seated before power
Kill cordWorn, attached to the driver, every time, no exceptions — the MAIB's small-craft fatality reports repeat this one line
COLREGS statusThe tender is a power-driven vessel under the Rules: lights after sunset, proper look-out, speed for the visibility and traffic — and local harbour speed limits
Dive supportRigid Alpha flag ≥1m (Rule 27(e)); divers briefed; wide berth and dead slow near other dive marks and SMBs
Night opsNav lights, spare torch, second means of comms, passage told to the bridge — a tender overdue at night is a SAR incident in the making
Helicopter Operations — The Deck Essentials

Yachts host helicopter transfers and medevacs; the OOW's brief: comms established on the agreed channel and the aircraft's instructions govern; steady course and speed as directed (typically wind fine on the port bow); the operating area stripped of loose gear — downdraught turns towels and cushions into missiles; crew briefed, nothing loose on their persons; fire party standing by.

Two absolutes: the winch wire is NEVER made fast to the vessel, and the wire or hi-line is not touched until it has earthed its static discharge. Both are drilled, both are asked in orals, and both have killed people when ignored.
Oral Exam Practice Questions
Question 1

Talk me through anchoring a 45m yacht in 20 metres of water.

Approach head to wind or tide and stop over the spot. In 20 metres I walk the anchor back on the gypsy to near the bottom rather than free-fall — a runaway cable and chain piled foul of the anchor are the risks. Dead slow astern, veering so the cable lays out along the seabed pointing at the anchor. Scope four to six times depth in chain — and depth is to the hawse, so I add the freeboard: call it 80 to 120 metres. Brought up is confirmed by the cable's language — it snatches taut, then eases to a steady light lead. Then anchor bearings and a transit immediately, GPS ring sized to scope plus length, position and marks logged, and the anchor watch briefed with its escalation triggers.
Question 2

Your anchor watch reports the transit has opened and the cable is snatching. Actions?

She's dragging. Master called immediately. Engines started — first job is easing the load: steaming gently up toward the anchor takes the weight off the cable and can save the hold. Veer more scope if I have swinging room — the catenary is the shock absorber. Then the decision, made early with the master: re-anchor properly with more scope and better holding, or weigh and stand out to sea — a dark anchorage full of dragging yachts in a gale is often more dangerous than open water. I don't drop the second anchor on reflex — it's a plan with a fouling risk, not a talisman. Lights, shapes and signals stay correct throughout, and it all goes in the log.
Question 3

What is snap-back, and how do you run a mooring deck around it?

Stored energy: a tensioned line that parts recoils along and around its leads at lethal speed — and the danger zone follows the line's path through every fairlead, not just the straight run, so modern practice treats the whole mooring deck as a dynamic danger area rather than painting fixed zones. My controls: positioning — nobody in a bight or a recoil path, briefed before the first line; load management — lines tended early and eased before they're extreme, never held against a surging load; equipment honesty — chafed lines retired, fairleads and winch brakes maintained and tested; and communication — winch to winch and deck to bridge on one plan, so no one is surprised by a load coming on.