Anchor types, holding power, scope calculation, ground tackle components, bottom types, the step-by-step anchoring procedure, anchor watch duties, kedging off, ColRegs Rule 30 lights and shapes, and prohibited anchorages — everything tested on the USCG captain's license exam.
7:1
Minimum scope — normal conditions
10:1
Scope for heavy weather and storm
Rule 30
ColRegs anchor lights and shapes
3–5%
Vessel weight as anchor size guide
The exam tests anchor selection by bottom type, relative holding power for weight, and proper use cases. Six anchor types appear consistently on USCG licensing exams. Know each by design, holding mechanism, best bottom, and limitations.
Danforth / Fluke Anchor
The Danforth anchor uses two large flat flukes mounted on a pivot at the head. When tension is applied, the flukes rotate and dig into the bottom, burying the anchor completely. The stock lies flat on the seabed, keeping the flukes at the correct angle for maximum penetration.
Holding Power
Very high for weight — highest ratio of any common anchor type
Best Bottom
Sand, soft mud — flukes must penetrate to hold
Limitations
Poor in grass, rock, coral; can foul rode if vessel swings far
Exam note: folds flat for deck storage; most popular recreational vessel anchor; the hinged flukes can trip if the vessel swings 180 degrees.
CQR (Coastal Quick Release) / Plow Anchor
The plow anchor resembles a farmer's plow. The hinged shank pivots on the crown, allowing the anchor to reset when the vessel swings to a new direction without breaking out. This self-resetting behavior makes it the preferred cruising anchor for offshore voyagers. It self-launches from a bow roller and is commonly stored on the bowsprit.
Holding Power
High — very reliable in varied conditions
Best Bottom
Sand, mud, grass — good all-around performance
Limitations
Heavier than Danforth for equivalent holding; can be slow to set in hard sand
Exam note: the hinged shank is the key feature — it allows the anchor to swing through 360 degrees without breaking out, unlike a fixed-shank anchor.
Bruce / Claw Anchor
The Bruce anchor has three curved claws that wrap around the shank. It has no moving parts, which makes it extremely reliable and simple to maintain. It can orient itself to set regardless of how it lands on the bottom. It is widely used on powerboats and motor yachts and self-deploys easily from a bow roller.
Holding Power
High — resets quickly after dragging
Best Bottom
Rock, coral, grass, mud — very versatile
Limitations
Bulky; does not fold for storage; lower holding power than Danforth per pound
Exam note: no moving parts makes it the most reliable anchor mechanically; preferred where bottom type is uncertain or where rock or coral is present.
Kedge Anchor (Navy / Admiralty Pattern)
The traditional kedge or Admiralty anchor has a stock perpendicular to the flukes that ensures at least one fluke always faces downward to hook into the bottom. It is used specifically to free grounded vessels (kedging off) and is carried as a second anchor for maneuvering purposes. It works in rock and coral where modern lightweight anchors fail.
Holding Power
Moderate — relies on hooking, not burying
Best Bottom
Rock, coral, hard bottom — hooks rather than buries
Limitations
Difficult to stow; awkward shape; rode can foul the stock
Exam note: the primary use of a kedge anchor on the exam is for kedging off a grounded vessel — this is the anchor deployed by dinghy to pull the vessel into deeper water.
Mushroom Anchor
The mushroom anchor is shaped like an inverted mushroom cap. It develops holding power by slowly sinking into soft sediment — a process that takes weeks or months. Once fully embedded, its suction-based holding power becomes very high. It is used exclusively for permanent moorings and fixed buoys, never as a cruising anchor.
Holding Power
Very high once set — but requires weeks to reach full holding
Best Bottom
Soft mud only — must be able to sink in gradually
Limitations
Not suitable for cruising; useless until properly embedded; poor in sand or hard bottom
Exam note: mushroom anchors are used for mooring buoys, aids to navigation (light buoys, channel markers), and permanent moorings — NOT for overnight anchoring by vessels underway.
Stockless (Navy) Anchor
The stockless anchor is the standard commercial and naval vessel anchor. It has no horizontal stock — the crown pivots so both flukes dig in simultaneously when tension is applied. Its compact shape allows it to be housed directly in the hawsepipe on large vessels and deployed rapidly by releasing the windlass brake. Holding power per pound is moderate, but commercial vessels compensate with very large anchor and chain weights.
Holding Power
Moderate per pound — adequate at commercial anchor sizes
Best Bottom
Sand, mud — most commercial anchorages
Limitations
Lower holding per pound than Danforth; not practical for small vessels
Exam note: stockless anchors are associated with commercial vessels and the Navy. Their key advantage is housing in the hawsepipe for rapid deployment on large ships.
| Anchor | Holding per Pound | Best Bottom | Primary Use |
|---|---|---|---|
| Danforth / Fluke | Highest | Sand, mud | Recreational vessels — main hook |
| CQR / Plow | High | Sand, mud, grass | Offshore cruising — self-resetting |
| Bruce / Claw | High | Rock, coral, grass | Powerboats — no moving parts |
| Kedge / Navy | Moderate | Rock, coral, hard | Kedging off — second anchor |
| Mushroom | Very high (set) | Soft mud only | Permanent moorings |
| Stockless | Moderate | Sand, mud | Commercial vessels — hawsepipe housing |
Ground tackle is the entire anchoring system — anchor, rode, connecting hardware, and windlass. Each component must be rated for the vessel and properly maintained. The exam tests terminology and the purpose of each component.
Rode
The line, chain, or combination connecting the anchor to the vessel. All-chain rode is strongest and provides catenary but is heavy. Nylon rope rode is lighter and elastic (shock-absorbing) but requires more scope. A combination rode — nylon with a chain leader — is most common on recreational vessels.
Chain leader length: typically 3 to 6 feet minimum; some vessels use 20 to 30 feet of chain at the anchor end to improve catenary and protect against chafe on rocks.
Chain
Short-link anchor chain is measured in shackles (90 feet each in US practice) or shots (90 feet or 15 fathoms). Chain is measured by the diameter of the metal in the link. G4 (Grade 40 or BBB) chain is standard for recreational vessels. High-test (G70) chain is stronger per size and used on commercial vessels.
Chain vs. rope: chain provides catenary (shock absorption through sag weight) and chafe resistance at the anchor. Rope provides elasticity as shock absorption but requires more scope for the same holding.
Shackle
A U-shaped metal connector with a threaded pin used to connect chain to anchor, or chain to swivel. Shackles must always be moused — the pin secured with seizing wire or a tie — to prevent unscrewing. A loose shackle pin can result in loss of the entire ground tackle.
Mousing technique: thread seizing wire through the hole in the pin and around the bow of the shackle, twist tight. Some mariners use cable ties as a simple alternative for recreational use.
Swivel
A rotating connector placed between the anchor and chain, or between chain sections. As the vessel swings through multiple headings, the rode twists. A swivel prevents that twist from accumulating and kinking the chain or binding the anchor shank. Not all anchors require a swivel but all rode systems benefit from one.
Swivels must be rated at least as strong as the chain they connect. An undersized swivel is the weakest link in the system. Always check swivel condition — they can corrode internally without showing external wear.
Bitter End
The inboard end of the anchor rode, secured inside the chain locker or to a structural strong point. It is the last resort when all rode has been paid out. The bitter end must be permanently attached — but secured with rope or a shear pin rather than chain so it can be cut in an emergency. Losing the bitter end means losing the anchor.
Best practice: secure the bitter end with a 3- to 4-foot piece of strong nylon line rather than a chain shackle. If forced to anchor in very deep water (emergency) or needing to slip the anchor quickly, the line can be cut with a knife.
Windlass
The windlass is the mechanical or electrical winch used to deploy and retrieve the anchor rode. A horizontal windlass (capstan) turns on a vertical axis and is used for line. An anchor windlass turns on a horizontal axis and is designed specifically for chain using a wildcatgypsy wheel that engages the chain links. Electrical windlasses require proper wiring — typically a dedicated heavy-gauge wire from the battery with a manual override.
Wildcat: the toothed drum that engages chain links on an anchor windlass. It is matched to a specific chain size — never use chain that does not match the wildcat specification.
Exam Memory Aid — Ground Tackle Order
From vessel to seabed: Windlass → Bitter End → Chain (in locker) → Swivel → Shackle → Anchor. Every connection must be inspected before deployment and every shackle pin must be moused.
Scope is the single most important factor in anchor holding power. An anchor at 3:1 scope has a fraction of the holding power of the same anchor at 7:1. The USCG exam regularly presents scope calculation problems.
The Scope Formula
Scope Ratio = Rode Length ÷ (Depth + Freeboard)
Rode Length = (Depth + Freeboard) × Scope Ratio
Depth
Water depth at the anchor drop point — use maximum expected depth including tidal rise
Freeboard
Height of the bow chock above the waterline — typically 3 to 6 feet on recreational vessels
Scope Ratio
7:1 normal conditions — 10:1 heavy weather or storm — some sources use 5:1 as bare minimum
Example 1 — Basic 7:1 Scope
Given: Water depth: 20 ft | Bow chock freeboard: 4 ft | Scope: 7:1
Work: (20 + 4) = 24 ft vertical distance. 24 x 7 = 168 ft of rode required.
Answer: 168 feet
Example 2 — Heavy Weather 10:1
Given: Water depth: 15 ft | Freeboard: 3 ft | Scope: 10:1
Work: (15 + 3) = 18 ft vertical distance. 18 x 10 = 180 ft of rode required.
Answer: 180 feet
Example 3 — Calculating Scope Ratio from Rode Deployed
Given: Rode deployed: 150 ft | Water depth: 18 ft | Freeboard: 4 ft
Work: Vertical distance = 18 + 4 = 22 ft. Scope ratio = 150 / 22 = 6.8:1
Answer: Approximately 7:1 scope
Example 4 — Accounting for Tidal Rise
Given: Current depth at anchor: 12 ft | Tidal rise: 5 ft | Freeboard: 4 ft | Scope: 7:1
Work: Maximum depth = 12 + 5 = 17 ft. Vertical distance = 17 + 4 = 21 ft. Rode = 21 x 7 = 147 ft.
Answer: 147 feet — calculated on HIGH water depth
Catenary is the sag in the rode caused by the weight of chain hanging in a curve between the vessel and the anchor. This curved section acts as a spring, absorbing surge loads before they reach the anchor. Catenary keeps the load at the anchor nearly horizontal, which is the ideal angle for maximum holding power.
Chain Rode — Catenary Effect
Nylon Rope Rode — Elasticity Instead
Exam Tip — Catenary in Heavy Weather
When a vessel surges heavily in a storm, the chain catenary straightens completely and the full load hits the anchor as a snatch load. At this point, increasing scope is the primary remedy. If the anchor cannot hold the snatch load, it will break out. This is why 10:1 scope is recommended in heavy weather — more rode means more catenary weight and a longer buffer before the chain goes taut.
Anchorage quality depends heavily on what the anchor is digging into. Chart symbols indicate bottom type — the exam tests which bottom types provide the best holding and which anchor designs work in each.
| Bottom Type | Chart Symbol | Holding Quality | Best Anchor | Notes |
|---|---|---|---|---|
| Firm Sand | S | Excellent | Danforth, CQR | Flukes bury deeply and hold; most reliable holding ground |
| Soft Mud | M | Good | Danforth, Mushroom | Anchors bury easily but suction can make retrieval difficult |
| Hard Sand | hS | Very Good | Danforth, CQR | Slightly harder to set initially; excellent holding once buried |
| Clay | Cl | Good | Danforth, CQR | Dense and cohesive; holds well but can be hard to penetrate |
| Grass over Mud | G / wM | Poor | Bruce, CQR | Grass mat prevents flukes from penetrating to mud below |
| Rock | Rk | Variable | Kedge, Bruce | Hooks into crevices rather than buries; can be impossible to retrieve |
| Coral | Co | Variable | Kedge, Bruce | Can hook well but anchor may be lost; causes environmental damage |
| Gravel / Shingle | G / Sh | Fair | CQR, Bruce | Shifts under load; less reliable than sand or mud |
Reading Chart Bottom Symbols
NOAA charts use abbreviated symbols inside the depth soundings or alongside sounding values to indicate bottom composition. Common symbols tested on the exam:
The Holding Ground Hierarchy
From best to worst for most anchor types:
Choosing the right anchorage is seamanship. The exam tests the factors a competent mariner evaluates before dropping the hook. A poor anchorage choice leads to dragging, collision, or grounding.
Water Depth
Minimum depth must be sufficient to float the vessel at the lowest predicted tide, including any surge or wave trough. Maximum depth affects scope requirements — very deep anchorages require enormous amounts of rode. The exam often tests calculation of required depth at low water given tidal range.
Exam tip: Use maximum (high water) depth for scope calculation. Use minimum (low water) depth to verify you won't touch bottom.
Bottom Type
Select anchorages with sand or mud bottoms. Avoid rock, coral, and heavy grass. Chart the bottom type before entering an anchorage. If bottom type is unknown, use a lead line with tallow (or a weighted cup of grease) to sample the bottom. Modern practice uses chart symbols.
Exam tip: If a chart shows rock or hard bottom, plan on using a kedge or Bruce anchor rather than a Danforth.
Swing Room
Every vessel in an anchorage swings in a circle around its anchor as wind and current shift. Swing radius equals vessel length plus rode deployed. In a crowded anchorage, note the rode type of neighbors — chain swings closer than rope. Two vessels anchoring at the same spot but with different rode types may collide when wind shifts.
Exam tip: Swing radius calculation: vessel length plus scope deployed. All swing circles in the anchorage must be non-overlapping.
Shelter
Evaluate wind and wave exposure from all quadrants. A cove sheltered from the prevailing wind may be open to dangerous wind and swell if the wind clocks overnight. Check the forecast for wind direction shifts. A good anchorage provides protection from the expected conditions on all sides that matter.
Exam tip: Check wind forecast for direction shifts 12 to 24 hours ahead. A northeast-facing cove that protects from southwest winds becomes exposed if the wind clocks to northeast overnight.
Current and Tide
Strong current affects scope requirements and swing behavior. In current, vessels lie to the current rather than the wind when current exceeds approximately 1 knot. In tidal rivers, vessels alternate direction with each tide, requiring full 360-degree swing room. Current also affects how the anchor sets — setting into a current can increase or reduce hold.
Exam tip: In tidal rivers with strong current, use a Bahamian moor (two anchors fore and aft) to reduce swing to the vessel length and prevent the vessel from fouling its own anchor on tide reversal.
Hazards
Check for charted hazards within the swing circle and in the dragging path — rocks, shoals, reefs, wrecks, cables, and pipelines. A vessel that drags overnight must not find a rock or shoal in the dragging path. Also check for traffic — do not anchor in shipping lanes, fairways, or areas where vessels may pass close.
Exam tip: When selecting an anchorage, trace the vessel's dragging path downwind or downcurrent — where does it go if the anchor does not hold? The dragging path must be clear of hazards.
The Pre-Anchoring Checklist
The exam tests knowledge of the correct sequence for anchoring. A methodical procedure ensures the anchor is placed accurately, sets firmly, and the vessel is properly secured before the crew relaxes.
Select the Anchorage
Using the chart, evaluate depth, bottom type, swing room, shelter, hazards, current, and prohibited areas. Identify the best spot within the anchorage and the approach path. Confirm the departure path is clear.
If anchoring at night, note landmarks for later bearing checks. Mark the GPS position of the intended anchor drop before maneuvering.
Prepare Ground Tackle
Shackle the anchor to the rode if not already done. Mouse all shackle pins. Flake the rode on deck in the order it will pay out. Confirm the bitter end is secured. Free the windlass brake and prepare to deploy.
Calculate rode length needed: (Depth + Freeboard) x Scope Ratio. Prepare to pay out that amount plus a safety margin. Mark rode at key lengths with paint or tape so you know how much is deployed.
Approach and Stop
Approach the selected spot heading into the prevailing wind or current — whichever is stronger. Slow to bare steerage or stop completely at the drop point. Never anchor while moving forward at speed — the anchor will skip along the bottom and not set.
In current, the bow should face into the current as the boat will lie to current once anchored. In wind with no current, face into the wind. If both are factors, the dominant force determines the heading.
Let Go — Lower the Anchor
With the vessel stopped or barely making sternway, lower the anchor to the bottom. Do NOT drop or throw the anchor — lower it until you feel it touch. Once on the bottom, pay out rode as the vessel drifts astern with the wind or current, or with a controlled astern burst of engine.
Paying out rode: a controlled astern drift spreads the rode and chain along the bottom in a line pointing toward the vessel, which improves the angle at the anchor and promotes good setting.
Set the Anchor
Once the full scope is paid out, snub the rode — stop the rode from paying out — and apply a brief, firm burst of astern power (typically 1000 to 1500 RPM in reverse for 30 to 60 seconds). A set anchor will not move; the rode will come taut and the vessel will stop. An anchor that has not set will drag astern.
Watch the bow — when the anchor sets, the bow will swing into the wind and the vessel will stop its astern motion. The rode will go taut from the bow chock at the correct angle. Check that you have not dragged past your intended position.
Fix Position and Post Anchor Watch
Record GPS coordinates of the anchor drop. Take compass bearings on two or more fixed objects ashore and record them. Display the proper anchor light (and day shape if applicable). Assign an anchor watch. Check that other vessels in the anchorage are not in your swing circle.
Best practice: set a GPS anchor alarm at a radius equal to your rode deployed plus 10 percent. The alarm will sound if the GPS position moves outside that radius — indicating a drag.
An anchor watch is an assigned crew member responsible for monitoring the vessel while at anchor. The exam tests what duties the anchor watch performs and how to detect and respond to a dragging anchor.
Anchor Watch Duties
Take and record bearings
Every 15 to 30 minutes, take compass bearings on two fixed objects ashore. Record each bearing. Any consistent bearing change indicates dragging.
Monitor depth sounder
If depth changes significantly while at anchor, the vessel is moving — either dragging toward shallower water or away into deeper water.
Check rode tension
A properly set anchor holds with steady catenary tension. Jerky, uneven tension or repeated slack-and-snap cycles indicate dragging.
Monitor weather
Watch barometer and sky for building conditions. Increasing wind may require paying out more scope or re-anchoring.
Watch for traffic
Other vessels entering the anchorage may not account for your swing circle. Be ready to maneuver or hail them on VHF.
Verify anchor light
Check that the anchor light is functioning throughout the night.
Signs of Anchor Dragging
Response to Dragging Anchor
Using Two Anchors
In storm conditions or when holding ground is suspect, deploying a second anchor improves holding dramatically. Two techniques:
Kedging is one of the most important practical seamanship skills and appears on both the OUPV and Master exams. It involves deploying a kedge anchor in the direction of deep water to pull the vessel off a shoal.
Kedging Procedure
Assess the grounding
Determine water depth on all sides. Which direction is deeper water? How hard is the vessel aground? Is the tide rising or falling? If the tide is rising, waiting may refloat the vessel without kedging. If the tide is falling, immediate action is required.
Prepare the kedge anchor
The kedge (or any available second anchor) and its rode are loaded into the ship's dinghy or tender. The rode is carefully coiled in the dinghy so it will pay out without fouling as the dinghy pulls away.
Deploy the kedge by dinghy
Row or motor the dinghy in the direction of deep water, paying out the rode as you go. Deploy the kedge anchor well ahead of the vessel — typically at least one full rode length. Let go the anchor and confirm it is set by pulling hard on the rode from the dinghy.
Apply tension and power
With the kedge deployed, haul on the rode using the windlass or a sheet winch to bring the vessel toward the anchor. Simultaneously, use engine power astern (or ahead if the kedge is forward) to assist. Apply power gradually — sudden high-power attempts can damage the keel or rudder.
Rock the vessel if needed
Moving crew and fuel weight to one side, or using a boom and halyard to heel the vessel, can reduce the draft on the grounded side. Heeling reduces draft by tilting the keel, which may allow the vessel to slide off with kedge tension and engine.
Monitor for water ingress
Once free, immediately check bilges for water ingress — the grounding may have breached the hull. Verify structural integrity before proceeding. Note the grounding location on the chart and report to the Coast Guard if required.
Why Use a Kedge Specifically?
The traditional kedge or navy-pattern anchor is preferred for kedging because it can hook into rocky or hard bottom where a Danforth or CQR would simply skate. Hard bottom is common in shoal areas. A kedge does not need to bury — it catches on bottom irregularities to provide the necessary tension.
Emergency Kedging Considerations
Rule 30 of the ColRegs (and its Inland counterpart) governs the lights and shapes required for vessels at anchor and aground. This is heavily tested on USCG licensing exams. Know the thresholds and exact requirements by heart.
Vessels under 50 meters at anchor
One all-around white light in the forepart of the vessel where it can best be seen.
Exam mnemonic: under 50 meters — one white light forward.
Vessels 50 meters or more at anchor
An all-around white light in the forepart of the vessel PLUS a second all-around white light at the stern or near the stern, lower than the forward light.
Exam mnemonic: 50 meters or more — two white lights (forward higher, aft lower).
Vessels under 7 meters — exemption
A vessel less than 7 meters at anchor that is not in or near a narrow channel, fairway, or anchorage, or where other vessels normally navigate, is NOT required to show anchor lights.
Exam note: this exemption is frequently tested — the qualifying condition is location away from navigable areas.
Inland Rules Difference — Special Anchorage Areas
Under Inland Rules, vessels less than 20 meters anchored in a specially designated anchorage area established by the Secretary are NOT required to display anchor lights. This is an Inland Rules-only exemption and does not apply under International (ColRegs) Rules.
Vessel at anchor — daylight shape
One black ball displayed in the forepart of the vessel where it can best be seen. The ball must be at least 0.6 meters in diameter.
Vessel aground — daylight shape
Three black balls displayed in a vertical line where they can best be seen. A vessel aground also sounds different signals in restricted visibility.
Small vessel exemption
Vessels less than 7 meters that are not in or near channels, fairways, or navigable areas are exempt from the day shape requirement when at anchor.
Lights — Night
Shapes — Day
Memory aid: aground means three balls (day) or anchor lights plus two red lights (night). The two vertical red lights = danger, do not approach.
Inland Rule 30 (found at 33 CFR Part 83) applies on US inland waters. Rule 161 is a Western Rivers rule that relaxes anchor light requirements for barges and other vessels moored alongside riverbanks in certain river systems. The key exam point: on Western Rivers, barges moored to the bank display a white light at each end of the row or tier, not individual anchor lights on each barge.
Western Rivers vs. Inland vs. ColRegs — Exam Confusion
ColRegs apply on international waters. Inland Rules apply on US waters including Great Lakes and coastal harbors. Western Rivers Rules apply on the Mississippi River system and certain other inland rivers. The USCG exam may test all three regimes. When in doubt: ColRegs is the strictest, Inland is slightly more permissive, Western Rivers most permissive for anchored and moored commercial vessels.
Rapid ringing of a bell for about 5 seconds, at intervals of not more than 1 minute.
The rapid bell is the anchor signal — quick, continuous ringing for 5 seconds, then silence until the next minute.
Rapid ringing of a bell forward for about 5 seconds, immediately followed by rapid ringing of a gong aft for about 5 seconds, at intervals of not more than 1 minute.
100 meters or more: bell forward + gong aft. The gong is sounded aft to help approaching vessels determine the length and position of the anchored vessel.
Any anchored vessel may sound one short, one prolonged, and one short blast to warn an approaching vessel of the risk of collision.
This is optional but appropriate when another vessel appears to be approaching on a collision course in restricted visibility.
Not every body of water is open for anchoring. Federal, state, and local regulations designate areas where anchoring is prohibited. The USCG exam tests awareness of these restrictions and the regulations that govern them.
Traffic Separation Schemes
Vessels must not anchor in a traffic separation scheme or the inshore traffic zones, except in an emergency, to avoid immediate danger, or to engage in fishing in the inshore zone. Anchoring in a traffic lane creates a collision hazard for vessels transiting the lane.
Regulation: ColRegs Rule 10; 33 CFR Part 167
Cable and Pipeline Areas
Anchoring is prohibited in areas designated as submarine cable or pipeline areas and shown on charts. Dragging an anchor through a power cable or oil/gas pipeline can cause catastrophic damage. Cable areas are charted with specific symbols and notes.
Regulation: 33 CFR Part 334; charted restricted areas
Military and Security Zones
The Army Corps of Engineers establishes restricted areas around military installations, naval bases, and other sensitive facilities under 33 CFR Part 334. The USCG Captain of the Port establishes security zones under 33 CFR Part 165. Anchoring within these zones without authorization is prohibited and subject to civil and criminal penalties.
Regulation: 33 CFR Parts 165 and 334
Designated Fairways
Designated fairways, including those established under 33 CFR Part 166, are kept clear for vessel traffic. Anchoring in a fairway is prohibited except in emergency. Fairways are typically shown on charts and listed in Coast Pilot.
Regulation: 33 CFR Part 166
Special Anchorage Areas
Special anchorage areas are designated by the Secretary of Transportation for small vessels. Vessels less than 65 feet anchored in a designated special anchorage area under Inland Rules are exempt from the anchor light requirement. These areas are charted and listed in the applicable regulations.
Regulation: 33 CFR Part 110
Marine Sanctuaries and Protected Areas
National Marine Sanctuaries and Marine Protected Areas (MPAs) may restrict anchoring to protect sensitive habitats including coral reefs and seagrass. Anchoring restrictions in sanctuaries are established by NOAA and may require the use of mooring buoys instead of anchoring.
Regulation: National Marine Sanctuaries Act; 15 CFR Part 922
How to Identify Prohibited Anchorages
Emergency anchoring may be the last tool available to prevent a grounding or collision — engine failure, loss of steering, or uncontrolled dragging. The exam tests readiness and correct priority in emergencies.
Engine Failure Approach to Anchor
Anchor as a Collision Avoidance Device
If a vessel loses steering in a channel or approaches a collision hazard, dropping the anchor can stop or slow the vessel rapidly. This is an extreme last resort because it can result in collision with a following vessel and the anchor may not hold on a hard or rocky bottom. If anchoring in a traffic lane as an emergency measure, alert other traffic immediately on VHF Channel 16.
Slipping the Anchor in Emergency
If a vessel must leave an anchorage immediately (approaching storm, fire, vessel aground nearby and dragging toward you), the anchor may be slipped — the bitter end cut or released — leaving the anchor on the bottom. Mark the position with a buoy if possible to recover later. The bitter end should be attached with a line (not chain) for exactly this reason — it can be cut with a knife.
Re-Anchoring After a Drag
These 16 questions mirror the format and content of anchor handling questions on the USCG OUPV and Master licensing exams. Read each question, formulate your answer, then expand to see the explanation.
What scope ratio does the USCG recommend for normal anchoring conditions?
Scope7:1 — seven feet of rode for every one foot of depth plus freeboard. Some sources cite 5:1 as a minimum; the exam often uses 7:1 for normal and 10:1 for storm or heavy weather. Always calculate depth using the maximum expected depth including tidal rise.
A vessel is anchored in 18 feet of water. The bow chock is 3 feet above the waterline. How much rode is needed at 7:1 scope?
Scope MathVertical distance equals 18 plus 3 equals 21 feet. Rode equals 21 multiplied by 7 equals 147 feet. Round up to the next shackle or chain length as needed.
Which anchor type has the highest holding power for its weight and is best for sand and mud?
Anchor TypesThe Danforth (fluke) anchor offers the highest holding power to weight ratio among common anchor types. Its large flat flukes bury deeply in sand and mud. It is the most common choice for recreational vessels.
A vessel anchored in an area with grass over mud is experiencing repeated anchor drag. What should the skipper do?
Bottom TypeShift to an anchor better suited to penetrating grass — a Bruce or plow anchor — or relocate to an anchorage with sand or clear mud bottom. Grass prevents Danforth flukes from penetrating to the holding bottom beneath. Increasing scope alone will not solve the problem if the anchor cannot set.
Under ColRegs Rule 30, how many all-around white lights does a vessel of 60 meters display at anchor?
Rule 30Two — one all-around white light in the forepart of the vessel and a second, lower all-around white light aft. Vessels under 50 meters display only one all-around white light. Remember: the threshold is 50 meters, not 60 or 100.
What day shape does a vessel at anchor display during daylight hours?
Day ShapesOne black ball displayed in the forepart of the vessel where it can best be seen. Vessels less than 7 meters anchored away from fairways and channels are exempt. Vessels in designated special anchorage areas under Inland Rules may also be exempt.
What is the primary purpose of catenary in an anchor rode?
CatenaryCatenary — the downward sag of chain under its own weight — acts as a shock absorber, reducing snatch loads on the anchor. It also keeps the pull at the anchor more horizontal, increasing holding power. When the vessel surges, the catenary straightens rather than the anchor breaking out.
What does it mean to mouse a shackle?
Ground TackleMousing means securing the shackle pin with wire, seizing wire, or a plastic tie so it cannot unscrew and fall out from vibration or movement. An unmoused shackle can unscrew over time, resulting in loss of the anchor and chain. All shackles in ground tackle should be moused before deploying.
A vessel runs aground. The skipper wants to kedge off. What is the first step?
KedgingDeploy the kedge anchor by dinghy or over the bow in the direction of deep water — not in the direction the vessel is currently heading. The anchor must be placed well ahead of the vessel (typically one or more rode lengths) so the windlass can haul the vessel toward it. Then use the windlass or sheet winch to haul on the kedge rode while applying cautious astern engine power.
What is the minimum distance a vessel must maintain from a submarine cable area when anchoring?
Prohibited AreasA vessel must not anchor in or near a submarine cable area designated on the chart. Specific exclusion distances vary by regulation and chart notation, but the governing rule is 33 CFR Part 334 and applicable Special Notices to Mariners. The practical exam answer: avoid anchoring in any cable or pipeline area marked on the chart.
While on anchor watch, you notice the compass bearing to a fixed lighthouse has changed by 10 degrees over 15 minutes. What does this indicate?
Anchor WatchThe vessel is likely dragging anchor. A consistent bearing change to a fixed object indicates the vessel is moving relative to the fixed point. Immediately check depth, rode tension, and GPS position, then alert the captain. Take action to reset the anchor or pay out more scope.
What is swing room and how is the swing radius calculated?
Anchorage SelectionSwing room is the circular area a vessel sweeps around its anchor as wind and current shift. Swing radius equals the vessel length plus the length of rode deployed. All anchored vessels in the area must have non-overlapping swing circles. Vessels on chain may swing closer to their anchor than vessels on nylon, causing mismatched swing circles in mixed anchorages.
What is the bitter end and what should be done with it?
Ground TackleThe bitter end is the inboard end of the anchor rode secured inside the chain locker or to a strong point on the vessel. It must always be secured so the entire anchor and rode cannot be lost overboard — but it should also be accessible to be cut in a genuine emergency (such as needing to make way quickly in a dragging situation). The bitter end should be secured with a piece of line rather than chain so it can be cut with a knife if necessary.
Under what weather conditions should scope be increased to 10:1?
Heavy WeatherHeavy weather — wind above approximately 25 to 30 knots, storm or gale conditions, or severe squall conditions. At 10:1, the catenary and rode length provide maximum holding power and shock absorption. Also consider using two anchors in a V-pattern (Bahamian moor) or bow and stern anchors to limit swing in tight anchorages during storms.
A mushroom anchor is deployed for what purpose and in what conditions?
Anchor TypesMushroom anchors are used for permanent moorings in soft mud — not as cruising anchors. They require extended time (weeks to months) to sink into soft bottom and develop their holding power, which then becomes very high. They are impractical for overnight anchoring because they must be pre-set. They are commonly used for mooring buoys, channel markers, and light buoys in soft-bottom harbors.
What signals does a vessel at anchor sound in restricted visibility under ColRegs Rule 35?
SignalsA vessel at anchor less than 100 meters: a rapid ringing of a bell for about 5 seconds, at intervals of not more than 1 minute. A vessel at anchor 100 meters or more: the rapid bell forward plus a rapid ringing of a gong aft immediately after the bell. These signals warn approaching vessels of an anchored obstacle.
Scope Ratios
Anchor Lights (Rule 30)
Day Shapes
Best Anchor per Bottom
Drag Detection
Restricted Visibility at Anchor
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