Anchoring in Challenging Conditions

Prerequisites

• RYA Day Skipper practical competence in choosing an anchorage, anchoring in settled conditions, picking up a mooring and weighing anchor, and the shorebased knowledge of chart symbols for seabed type and tidal height calculations (see the Course Plotting and Tidal Navigation lesson).
• Coastal Skipper course entry experience: 15 days, 2 days as skipper, 300 miles, 8 night hours.
• At Coastal Skipper / Yachtmaster Coastal level you must be able to choose an anchorage for changing conditions, calculate scope and swinging room through the tide, use two anchors when appropriate, keep an effective anchor watch, and deal with a dragging or fouled anchor.

Learning Objectives

This lesson covers the RYA Yachtmaster Coastal / Coastal Skipper syllabus items on anchoring, and the related Day Skipper items on mooring buoys. By the end you will be able to:

• Choose an anchor and anchorage using seabed type, shelter, forecast wind shifts, swell and escape routes (RYA syllabus: selection of anchorages and anchors).
• Size ground tackle, and inspect and mark the cable (RYA syllabus: ground tackle and its care).
• Explain catenary and scope, and calculate the length of cable for the tidal range and conditions (RYA syllabus: scope and holding).
• Plan the swinging circle and check clearance at all states of tide (RYA syllabus: swinging room and tidal clearance).
• Set, test and watch an anchor, and detect dragging early (RYA syllabus: anchoring procedure and anchor watch).
• Use two-anchor techniques: Bahamian moor, anchors in tandem or in a V, bow and stern, kedge (RYA syllabus: use of two anchors).
• Anchor in swell and strong tidal streams, and recover a fouled anchor (RYA syllabus: anchoring in adverse conditions; weighing and recovery).
• Med moor using your own anchor, and pick up and leave a mooring buoy (RYA syllabus: berthing and mooring).
• Show the correct lights and shapes at anchor (COLREGs Rule 30) and keep a legally and practically sound anchor watch.

Why Anchoring Is a Skill, Not a Chore

More yachts are lost or damaged at anchor than most owners expect: dragging onto rocks or other boats, a wind shift that turns a sheltered bay into a lee shore, a fouled anchor in a busy harbour. Almost all of these are avoidable by careful planning, adequate scope and a proper watch. On the Yachtmaster Coastal exam you may be asked to anchor in a place and at a time of the examiner's choosing, to justify your choice, to calculate your scope, and to explain what you would do if the anchor dragged at 0300.

Choosing the Anchorage

A good anchorage gives:

1. Shelter from the present wind and sea, and from the wind direction forecast for the whole time you will be there. A bay that is perfect in a westerly becomes a lee shore when the wind veers northwest behind a cold front.
2. Good holding ground (see below).
3. Suitable depth: enough at low water for your draught plus a safety margin, and not so deep at high water that you cannot lay enough cable.
4. Swinging room clear of other boats, rocks, moorings and the shoreline at all states of tide.
5. No obstructions on the bottom: cables, pipelines (marked on the chart), wrecks, moorings, oyster beds.
6. Out of channels and fairways, and clear of where ferries and fishing boats manoeuvre.
7. An escape route you can follow at night if the wind shifts, with clearing bearings or lights.
8. Shelter from swell that wraps round headlands even when the wind is offshore.

Read the pilot book and almanac for local holding, prohibited areas (anchor with a crossed-out symbol on the chart) and how the anchorage behaves in different winds.

Planning Around the Forecast and the Chart

Before you commit to an anchorage, do the following at the chart table:

1. Get the forecast for the whole period you will be there, and the shipping forecast trend. Note the wind direction now, the expected shifts and times (a frontal passage usually veers the wind 90 degrees or more), and gusts.
2. Draw the lee shore. For each forecast wind direction, mark which shores would be downwind of you. An anchorage with open water to windward and rocks to leeward is the dangerous one.
3. Check the tide. The times and heights of HW and LW during your stay (tide tables and the tidal curve), and the stream through the anchorage.
4. Read the pilot book and almanac for the recommended anchoring areas, holding, hazards and local rules, for example prohibited anchoring near cables.
5. Choose clearing bearings or a transit that keeps you off the nearest danger, and note a waypoint outside the entrance for a night exit.
6. Decide your trigger for leaving: for example, if the wind exceeds Force 6 or backs south, leave for the harbour 8 miles east.

The boat will lie to the stream where it is strong, and to the wind where the stream is weak; this matters for choosing the side of a bay and the swinging room.

How strongly does the wind load your anchor? The force on the boat is roughly proportional to the square of the wind speed. A boat that pulls with 100 kg in 17 knots will pull roughly 400 kg in 34 knots, and gusts are higher still. That is why ground tackle that is perfectly adequate in Force 4 can fail in Force 8: always size and lay your tackle for the worst you expect, not the average.

Anchors and Holding Ground

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Holding ground, using chart abbreviations:

A yacht should carry a main (bower) anchor sized generously for the boat (manufacturers' tables are a minimum; go a size up for cruising), plus a kedge, typically a lighter flat-fluke anchor with a short length of chain and a long warp.

Sizing ground tackle

Indicative figures for a modern new-generation anchor on a cruising monohull (always check the manufacturer's table for the actual boat displacement and windage, and size up for exposed anchorages):

Older designs (CQR, Bruce) need to be a size or two bigger than new-generation anchors for the same holding. The windlass gypsy must match the chain size and calibration exactly, or the chain will jump and jam.

Rode: chain, rope or both

• All chain: the best option for most cruising yachts. It is heavy, so it provides the catenary, resists abrasion on rock and coral, and is easy to manage with a windlass.
• Chain and rope: a length of chain (at least equal to the boat length, ideally 20 to 30 m) spliced to three-strand or plaited nylon rope. Lighter, but needs more scope because the rope provides little catenary. Fine for a kedge and for lighter boats.
• Rope: nylon stretches, absorbing shock, but chafes on rock, so a short chain length next to the anchor is essential.

Marking and securing the cable

Mark the cable so you know how much is out: for example one marker at 10 m (red), 20 m (yellow), 30 m (blue), and so on, or paint or cable ties every 5 metres. Secure the bitter end (the inboard end) in the chain locker with a lashing that can be cut in an emergency, not a shackle you cannot reach. Mouse every shackle with stainless seizing wire or cable ties, so the pin cannot unscrew.

Inspecting the tackle

At the start of each season and after any rough anchoring: check the chain for rust and worn links (a link worn to less than 90 per cent of its diameter is due for replacement), check that the swivel and shackles are not worn or bent, check the anchor for bends or cracks, and check the windlass and its breaker. Test the snubber's chafe points. An anchor is only as strong as its weakest link, and the weakest link is often a shackle.

Scope and Catenary

The anchor holds best when the pull on its shank is horizontal. If the pull lifts the shank, the anchor breaks out. The weight of chain lying on and hanging from the seabed creates a curve, the catenary, so that the pull at the anchor is horizontal even though the bow is above it.

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The catenary also acts as a shock absorber: as gusts pull the boat back, the chain lifts and straightens, absorbing energy before the anchor is loaded. In very strong winds the chain is pulled almost straight, and then the length of cable (scope) matters more than chain weight because a longer straight cable gives a lower angle at the anchor.

Scope is the ratio of cable length to the depth of water from the bow roller to the seabed.

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Calculating the depth to use

Use the depth at high water (or the highest tide during your stay), plus the height of the bow roller above the water. The depth reading on the sounder is from the transducer, so correct for its offset.

Example: You anchor 2 hours after low water. The sounder (set to read below the surface) shows 3.8 m. From the tide tables the height of tide now is 1.2 m and high water will be 4.6 m, so the tide will rise another 3.4 m. The bow roller is 1.0 m above the water.

Maximum depth = 3.8 + 3.4 = 7.2 m. Add 1.0 m for the bow: 8.2 m.

• Moderate conditions, all chain at 4:1: 8.2 x 4 = 33 m. Let out 35 m.
• Strong wind forecast, 6:1: 8.2 x 6 = 49 m. You carry 50 m of chain: let out all of it and add a rope extension or nylon snubber.

Also check the depth at low water under the boat when it swings to the full extent of its cable: the anchor may be in 4 m but the stern may lie over a 1 m patch.

A quick rule of thumb and the effect of a snubber

For an all-chain cable a rule of thumb is "depth plus freeboard, times four, in settled weather; times six, if anything is forecast; times eight in a gale". For chain and rope the multipliers are one or two higher at each stage. If you are in doubt, put out more, provided you have swinging room. A longer scope also reduces the angle of the pull at the anchor, which improves holding by a large margin: roughly speaking, going from 3:1 to 7:1 can double the holding capacity of an anchor.

Increasing scope as the weather worsens

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If the wind is forecast to rise, lay the extra scope before it rises, provided you have the swinging room. Letting out more chain once the anchor has dragged rarely works as well as resetting it properly.

Swinging Circle

The boat swings around the anchor with wind and stream. The radius of the circle is roughly the scope laid out plus the length of the boat. Other boats swing differently (a motor cruiser on rope swings more freely than a heavy yacht on chain; a yacht lies to the stream, a motorboat to the wind), so give extra space.

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Plot the anchor position, draw the circle on the chart, and check that nothing within it dries or is shallower than your draught plus a margin at low water. In a tidal anchorage you will swing through 180 degrees at each turn of the tide.

Anchoring Procedure

The following is the sequence the RYA examiner expects to see in a practical test.

1. Prepare: anchor freed from its securing, chain flaked or the windlass clutch checked, enough cable marked (paint or coloured markers every 5 or 10 m), crew briefed on hand signals. Note your intended position and depth.
2. Approach slowly, heading into whichever of wind or stream is stronger (look at how other boats are lying).
3. Stop the boat over the chosen spot. Lower the anchor to the bottom (do not throw a pile of chain on top of it).
4. Fall back under the wind or stream, or with gentle astern power, paying out chain so it lies in a straight line along the seabed rather than in a heap.
5. When the planned scope is out, snub the chain and let the boat's momentum dig the anchor in.
6. Set it: with the chain held, go astern gradually up to about half to two-thirds of full revs for 20 to 30 seconds. Check transits abeam: if they do not move, the anchor is holding. If the chain judders, the anchor is dragging.
7. Secure: put on a snubber (see below), hoist the black anchor ball by day; show the all-round white anchor light at night.
8. Record the position, depth, time, scope and transits in the log; set the anchor alarm.

Anchoring under sail and at night

You may be asked to anchor under sail, for example if the engine has failed. Approach on a close reach or close-hauled so that the boat can be stopped by easing the sheets and rounding up. Drop the mainsail and the headsail as the boat nears the spot, or let the sails flap to stop the boat. Drop the anchor as the boat comes to a stop and pays astern, and set it in the normal way, perhaps by backing the headsail. Practise this in good conditions beforehand.

At night, choose a daylight recce if you can. If you must go in at night, use the chart, a sounder and radar to identify clear water, and have a crew member forward with a torch (red light to preserve night vision). Anchor in a slightly deeper spot than you would in daylight and with more scope, and set the alarm earlier than you would in daytime. Show the anchor light before you drop the anchor.

Lights and shapes at anchor

Under COLREGs Rule 30, a vessel at anchor shows by night an all-round white light in the fore part (and for vessels 50 m and over, a second white light aft, lower); by day, one black ball in the fore part. A vessel under 7 m not anchored in or near a narrow channel, fairway or anchorage, or where other vessels normally navigate, is not required to show the light or shape. Most yachts use a masthead tricolour or an all-round white light on a pole; check that your anchor light works before you need it.

Rule 9 and local rules also apply: do not anchor in a narrow channel, in a traffic separation scheme or its approach, or where you would hinder other vessels. Anchoring is prohibited in many harbours and near cables and pipelines.

Snubbers and Anchoring in Swell

Chain is stiff and transmits every jerk directly to the bow roller and anchor. In swell, or when the boat sheers about, a snubber (a length of stretchy nylon rope, typically 5 to 10 m, attached to the chain with a chain hook or rolling hitch and led to a bow cleat) absorbs shock and stops chain noise.

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Swell also makes anchorages uncomfortable and dangerous. Rolling beam-on to the swell can be reduced with a kedge from the stern to hold the boat pointing into the swell, or a "flopper stopper" hung from the boom. A swell that is building in an anchorage may be a warning of a change in the weather offshore.

Anchor Watch and Detecting Dragging

An anchor that drags at night, onto rocks, is one of the commonest serious incidents for cruising yachts.

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• GPS anchor alarm: set the radius from the anchor position (not the GPS antenna's position when you dropped it) at scope plus boat length plus a small margin, typically 10 to 20 m. Some apps let you plot the actual anchor position.
• Transits: pick two objects in line abeam (a building and a headland, or a light and a hill at night), and check them regularly. A transit that opens means you have moved. A compass bearing is a weaker check because the boat swings.
• Depth alarm: set shallow and deep limits; an unexpected change shows movement.
• Physical checks: a dragging anchor transmits a rumbling vibration up the chain; a hand on the chain or snubber can feel it. The boat may start lying differently (beam-on to the wind instead of head to wind).
• Anchor watch: in a rising wind, keep a proper watch on deck, with the engine ready, rather than relying on alarms from below.

If you are dragging: start the engine, motor gently towards the anchor to take the load off, and recover the anchor. Then re-anchor with more scope, in a better spot, or leave. Do not just let out more chain while drifting towards danger.

Response to dragging at night: a procedure

1. Wake the skipper and all hands; put on lifejackets and foul-weather gear.
2. Start the engine and have it in neutral. Switch on the deck lights and the navigation lights.
3. Fix your position on the chart and check for other boats and hazards to leeward and the time you have.
4. Decide quickly: re-anchor, or leave. If the anchorage is crowded and the weather is worsening, leaving is usually the right answer.
5. Brief the crew: who goes forward, who helms, hand signals, and the escape route (a clear bearing to open water).
6. Recover the anchor while motoring slowly up to it (use the windlass only to take in slack).
7. Re-anchor with more scope away from other boats, or motor to the harbour. Record the event in the log.

Planning the anchor watch

In a rising wind, sleeping crew should not rely on an alarm alone. A suggested system for a stormy night: one person on deck or in the saloon with a view of the transits, a shift of 1 to 2 hours, a log entry every 15 to 30 minutes (transit bearings, depth, GPS distance from the anchor, wind speed and direction), the engine ready, and the next person woken in good time to relieve. For the skipper: sleep when you can, and give clear criteria for waking you, for example if the wind gusts above 35 knots, the alarm sounds, or anyone is unsure.

Using Two Anchors

Two anchors are used to reduce swinging room, to increase holding in a blow, or to hold the boat's head in a particular direction.

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Bahamian moor

Two anchors from the bow, laid about 180 degrees apart along the line of the tidal stream, with the boat lying midway between them on a swivel. As the tide turns, the boat swings around a small circle instead of the full scope. It is used in narrow tidal rivers and crowded anchorages.

To lay it:

1. Motor up into the stream past your chosen spot and drop the first (main) anchor.
2. Fall back, paying out about twice the normal scope, and set it.
3. Drop the second anchor at that point.
4. Haul back in on the main cable to the midpoint, letting out the second cable, so the boat lies midway with the right scope on each.
5. Join both cables with a swivel or shackle the second cable to the main chain and lower the join below keel depth, so the boat does not wind the cables round each other as it swings.

Disadvantages: if the wind blows strongly across the line of the anchors, both cables pull sideways and each holds less well than a single anchor; it is laborious to lay and recover; the cables can twist.

Two anchors in a V

For a strong wind from a known direction, two anchors laid from the bow about 30 to 60 degrees apart share the load and reduce sheering. Each must have adequate scope. If the wind shifts by 90 degrees or more, the cables can foul.

Tandem anchors

A second anchor shackled on a short length of chain ahead of the main anchor (backing, or "tandem") greatly increases holding in poor ground or storm conditions. It is laborious to recover and needs planning.

Bow and stern

An anchor from the bow and another from the stern (or a stern line ashore) keeps the boat pointing one way with almost no swing. Useful in a narrow creek with little room, or to hold the bow into the swell. It is dangerous if a strong wind or stream develops on the beam, because the load is enormous with the boat broadside to it. Use it only in settled conditions.

Kedge

A light anchor laid by the dinghy or from the boat can hold the boat's head off a hazard, limit swinging room, or be used to kedge off after grounding (laying the kedge out into deep water and hauling on it with a winch).

Anchoring in a Strong Tidal Stream

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• Anchor out of the strongest stream where possible: the edge of a channel, in a bay or behind a point.
• Approach heading into the stream, with enough speed to steer; drop at slow ahead over the ground, and let the stream carry you back as you pay out.
• At the turn of the tide the anchor is pulled from the opposite direction; check it resets. Some anchors (particularly flat-fluke and some ploughs) may break out and fail to reset. Consider a Bahamian moor in a narrow river.
• Wind against tide makes the boat sheer and sail around the anchor; watch the swinging circle and use a riding sail or a kedge to dampen it.
• Never anchor in a channel or fairway.

Weighing Anchor

1. Brief the crew and agree hand signals for the bow: direction of the chain, "up and down", "anchor aweigh", "anchor sighted".
2. Start the engine. Motor gently towards the anchor while the crew take in the slack; never use the windlass to pull the boat up to the anchor in a breeze, as it can burn out.
3. When the chain is vertical ("up and down"), the anchor should break out with the boat's motion or a little ahead power. Snub the chain and let the boat's momentum break it out if necessary.
4. Once "aweigh", the boat is free and drifting: the helm must steer immediately to keep clear of hazards and other boats.
5. Recover and secure the anchor, wash off mud, and secure the chain locker.

In strong winds, have sails ready to set or engine power ready, plan your exit route before breaking out, and make sure the anchor will not swing and damage the bow as it comes up.

Fouled Anchor

An anchor can catch under a chain, mooring, cable or rock.

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1. Change the angle of pull: motor slowly in a circle around the anchor with the chain short, or haul from different directions, and try pulling from the opposite direction to how it was set.
2. Trip line: if you rigged one (a line from the crown of the anchor to a small buoy on the surface, long enough for high water), haul on it to pull the anchor out backwards. Rig one whenever you suspect a foul bottom.
3. Gentle surging with the boat's motion in a swell can lift it out.
4. If caught under a chain or cable, haul it up as far as possible, pass a line under the obstruction, secure both ends on board, lower the anchor free, then slip the line.
5. Dive only if the conditions and depth are safe and a competent diver is available.
6. Abandon: buoy the chain with a fender and line so you can return to recover it, and slip it from the bitter end. The inboard end of the chain should always be secured by a lashing that can be cut, not a shackle.

Never haul on a fouled cable that is caught under a power or communications cable: report it and seek advice.

Picking Up and Leaving a Mooring Buoy

Mooring buoys are common in harbours and popular anchorages, and the technique is part of the Day Skipper syllabus that the Coastal Skipper candidate is expected to carry out fluently in any weather.

1. Assess the wind and the stream (look at the other boats). Approach the buoy heading into the stronger of the two, so you can stop with the buoy at the bow.
2. Prepare a mooring line or two lines, one passed through the buoy ring (or round the buoy pickup loop) and back to the boat. Lead it outside everything (guardrails, shrouds) and through the bow fairlead, with the bitter end made fast on a cleat. A boathook and a second line should be to hand.
3. Brief the crew: who is on the bow, the hand signals, and the stopping point. Use hand signals because shouting is hard to hear against the wind.
4. Approach slowly, with the buoy to windward or to the side where it will not drift under the hull. Stop the boat with the buoy at the bow, in neutral, so that the propeller does not catch the pickup line.
5. Pick up the loop with the boathook or by hand and pass the line through the ring; make fast on the bow cleat. Take a turn first, then secure it with a round turn or a cleat hitch. Check that the line leads well away from chafe and that you are not sitting on the buoy.
6. Adjust the lines so that the buoy cannot knock against the hull and add chafe protection.
7. To leave: release the end of one line and let it run through the ring; motor slowly away from the buoy, clear of the pickup line, and recover the line aboard.

A bridle of two lines to the buoy, one from each bow cleat, prevents the boat from sheering about the buoy and is good practice in a blow.

Check the owner or harbourmaster if the mooring is private; a buoy's pickup may be old and worn, so inspect it and use two lines rather than relying on one.

Mediterranean Mooring with Your Own Anchor

In harbours without lazy lines, yachts lie stern-to the quay with their own anchor laid out ahead.

1. Prepare two stern lines, fenders on both sides, the anchor ready to drop, the passerelle ready.
2. Line up with the gap, about 3 to 4 boat lengths out (more in deeper water, so you will have at least 3 to 4 times the depth of chain out when the stern reaches the quay).
3. Drop the anchor as you begin reversing, and pay out chain steadily as you reverse. Do not let it run free.
4. About one boat length from the quay, snub the chain to set the anchor and slow the boat.
5. Get both stern lines ashore, then tighten the chain to hold the stern clear of the quay, and adjust.
6. When leaving, drive forward slowly along the line of your chain, and be ready for your anchor to come up with someone else's chain across it.

Cross-wind is the difficulty: the bow blows off as soon as you reverse slowly. Approach with the bow up into the wind, lay the anchor slightly upwind of your slot, and keep enough speed to steer.

Worked Example: Swinging Circle and Scope for Different Boats

You are in a harbour with a stream of 2 knots, wind of 15 knots and HW at 1800. At 1400 the depth by the sounder is 3.6 m (it is set to show the depth below the transducer; the transducer is 0.4 m below the waterline), the height of tide is 2.1 m and HW is 4.7 m at 1800; so the tide will rise a further 2.6 m. The bow roller is 1.1 m above the water. You have a 12 m yacht with all chain.

1. Depth at the transducer is 3.6 m, plus 0.4 m to the waterline: 4.0 m of water now.
2. Rise to HW: 4.7 minus 2.1 = 2.6 m. Maximum depth = 4.0 + 2.6 = 6.6 m.
3. Add the bow roller height: 6.6 + 1.1 = 7.7 m.
4. Scope for 15 knots (settled) at 5:1: 7.7 x 5 = 38.5 m: let out 40 m.
5. Swinging radius = 40 m + 12 m = 52 m. On the chart, draw a 52 m circle. At LW (height of tide about 0.5 m, say) the water over the charted 2.0 m contour would be 2.5 m deep, which leaves only 0.7 m under a 1.8 m keel: too tight, so either anchor further from that contour or reduce the swing.
6. Check also that the boat will not swing into the neighbouring yacht: if they have 30 m of rope and a 10 m boat, they swing with a radius of about 40 m. Centre-to-centre you need at least 52 + 40 = 92 m for no overlap, or you agree to anchor on a line across the stream, so you lie the same way.

This level of calculation, done aloud at the chart table with real figures, earns marks in the oral and shows the examiner that you do not rely on guesswork.

Worked Example: Overnight in an Exposed Bay

You plan to spend the night in a sandy bay on the south side of a headland. The forecast: southwest 4 to 5, veering west 5 to 6 overnight, then northwest 4. Your boat: 10 m, draws 1.8 m, 50 m of 10 mm chain plus 30 m of rope, Delta main anchor and a Fortress kedge.

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Assessment:

• Southwest: the bay is open to the south, so swell will roll in until the wind veers. West: the headland gives shelter. Northwest: good shelter, but the shore becomes a lee shore if you are tucked too close in to the north side.
• Seabed: sand (S) shown on the chart, depths 5 to 8 m. Tonight's high water gives 2.2 m of rise above the present height.
• Escape route: if the wind backs south instead, the bay becomes untenable; plan an exit on a lit transit to the harbour 8 miles east.

Calculations:

1. You choose a spot with 5.5 m now. Add 2.2 m for the rising tide and 1.0 m for the bow roller: 8.7 m.
2. With force 6 forecast and some swell, use 6:1: 8.7 x 6 = 52 m. Let out all 50 m of chain plus 5 m of rope, or settle for 50 m of chain (5.7:1) with a long nylon snubber. Choose the latter, and plan to add rope if the wind exceeds force 6.
3. Swinging radius: about 50 m plus 10 m = 60 m. On the chart, a 60 m circle from the chosen spot clears the 2 m contour by 40 m on the north side at low water. Good.

Execution:

1. Approach into the southwest wind. Drop the Delta, fall back paying out 50 m, snub, and set at two-thirds astern for 30 seconds. Transits (a white house in line with a church tower abeam) hold steady.
2. Because of the swell from the south, lay the Fortress kedge from the dinghy about 45 degrees off the line of the main cable, on the south side, to reduce rolling and sheering. Keep it on a separate rope so it can be released quickly.
3. Rig a 10 m nylon snubber. Anchor ball up; anchor light on at dusk.
4. Set the GPS alarm at 65 m radius centred on the anchor position, and a depth alarm at 3 m.
5. Night anchor watch: one person on watch in the cockpit, rotated every 2 hours, until the wind has veered west and settled. Note transits, depth and the GPS distance to the anchor every 30 minutes.
6. At 0300 the wind veers west force 6: the boat swings, the kedge is now pulling at an awkward angle and starts sheering the boat. You recover the kedge rope (marking the kedge with a buoy) and lie to the main anchor, now with the headland providing shelter.

This is the kind of thinking the examiner expects: the forecast drives the choice of spot, the scope, the use of the kedge and the watch plan.

Common Mistakes

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• Too little scope, often from using the depth at low water and forgetting the bow height. Calculate for high water plus freeboard.
• No anchor watch or alarms when the weather is changing.
• Wrong anchor for the bottom, for example a flat-fluke anchor in weed or a fisherman in mud.
• Ignoring the tide: the swinging circle and depth change; the anchor must reset when the stream turns.
• Dumping chain in a heap on top of the anchor so it fouls.
• Not setting the anchor by going astern firmly.
• Poor chain management: unmarked cable, no securing lashing on the bitter end, unchecked shackles (mouse them with wire or cable ties).
• Anchoring too close to other boats, especially those lying to rope or of a different type.
• Anchoring in the wrong place on a falling tide, and discovering at low water that the keel is aground.
• Forgetting anchor lights or using a light that is too dim or hidden.
• Letting the bitter end go unsecured, so that the whole cable is lost.
• Trusting the GPS alarm alone in a gale, without a person on watch.
• Relying on one line on a mooring buoy or not checking the pickup for wear.

Summary

• Choose an anchorage for the whole forecast period: shelter, holding, depth, swinging room, swell and an escape route.
• Match the anchor to the seabed; sand, mud and clay hold best; weed and rock are unreliable.
• The anchor holds when the pull is horizontal. Catenary and scope achieve this: 4:1 all chain in moderate conditions, 6:1 for chain and rope or in strong winds, more in storms.
• Calculate scope from the maximum depth during your stay plus the bow height, and check the swinging circle at low water.
• Set every anchor by going astern; confirm with transits. Use a snubber in swell.
• Keep an anchor watch with GPS and depth alarms, transits and physical checks. If dragging, motor up and re-anchor.
• Use two anchors (Bahamian moor, V, tandem, bow and stern, kedge) for the right situation and understand their weaknesses.
• Rig a trip line on suspect ground; recover a fouled anchor by changing the angle of pull, using the trip line, lifting the obstruction, or buoying and slipping the cable.

Examiner Tips

• Explain why you chose the spot as you anchor: the forecast, the lee shore, the depth and tide, the holding and the swinging room.
• Lay the chain properly: do not let it pile up on the anchor. A tidy scope is easy to see from the helm.
• Show a transit or a bearing to prove that the anchor is holding, and record it.
• State your scope in numbers, and be able to calculate it from the tide table.
• Brief the crew before approaching, and use hand signals for the bow.
• If the examiner asks you to weigh anchor, get the engine running, take the load off with the engine, not the windlass, and check that the anchor is clear before moving off.

Check Your Understanding

1. Why does an anchor drag when the scope is too short?

Answer: The pull on the shank is angled upwards rather than horizontal, which lifts the anchor out of the seabed.

1. It is low water with 3 m on the sounder (reading below the surface). The tide will rise 4 m and the bow roller is 1.2 m above the water. How much all-chain cable do you need at 4:1 and at 6:1?

Answer: Maximum depth plus bow height = 3 + 4 + 1.2 = 8.2 m. At 4:1, 33 m; at 6:1, 49 m.

1. How do you decide the radius of your GPS anchor alarm?

Answer: Scope laid out plus the boat's length plus a small margin, measured from the anchor's position.

1. What is a Bahamian moor and when is it used?

Answer: Two anchors laid from the bow about 180 degrees apart along the line of the tidal stream, with the boat lying midway. It reduces the swinging circle in narrow tidal rivers or crowded anchorages.

1. What is the weakness of a Bahamian moor?

Answer: A strong wind across the line of the anchors pulls both cables sideways and each holds poorly; cables can twist; it is laborious to lay and recover.

1. Which anchor type is particularly poor in weed and may fail to reset when the tide turns?

Answer: The flat-fluke (Danforth or Fortress) type.

1. Name three ways to detect that your anchor is dragging.

Answer: Transits abeam opening; GPS anchor alarm or position moving outside the circle; depth alarm or unexpected depth change; vibration felt through the chain; the boat lying differently to the wind.

1. Your anchor is caught under a heavy ground chain. What can you do?

Answer: Haul the anchor and obstruction up as far as possible, pass a line under the ground chain and secure both ends aboard, lower your anchor to free it, then slip the line. If that fails, buoy your cable and slip it, and return to recover it.

1. Why use a nylon snubber with an all-chain cable?

Answer: Nylon stretches and absorbs shock loads, reducing jerking on the anchor, bow roller and cleats, and stops chain noise.

1. In a Med moor with your own anchor, roughly where do you drop it?

Answer: About 3 to 4 boat lengths from the quay (more in deep water), so that enough chain is out to give adequate scope when the stern reaches the quay.

1. Your sounder reads 4.0 m (depth below the waterline). HW is 3.0 m higher than the present height of tide. The bow roller is 1.0 m above the water. How much chain is needed at 5:1?

Answer: Maximum depth = 4.0 + 3.0 + 1.0 = 8.0 m. At 5:1 you need 40 m of chain.

1. What lights and shapes must a 10 m yacht show at anchor off a busy harbour, and what is the legal exception for small vessels?

Answer: One all-round white light at night (Rule 30) and one black ball by day. Vessels under 7 m that are not in or near a narrow channel, fairway or anchorage, or where other vessels normally navigate, need not show them.

1. Describe how to pick up a mooring buoy in a cross-wind and stream.

Answer: Assess the wind and stream and approach heading into the stronger, with a line led outside everything and a crew briefed on the bow. Stop with the buoy at the bow, pick up the loop with the boathook, pass the line through the ring and cleat it, then adjust the lines and add chafe protection. To leave, release one end and let it run through the ring, then motor clear.