Complete guide to ground tackle, scope calculation, holding ground, multiple anchor techniques, marlinspike seamanship, single-screw vessel handling, and COLREGS Rule 9 — everything tested on the USCG OUPV exam.
Heavily Tested Topics
Also Tested
Selecting the correct anchor for the bottom type is one of the most tested concepts on the OUPV exam. Matching anchor to substrate determines whether you hold or drag.
Holding: Excellent — pivoting shank allows the anchor to reset if direction changes
Weakness: Poor in rock and coral; can be slow to set initially
Typical Weight: Heavier than Danforth for same holding power — typically 15–45 lbs for cruising boats
Holding: Exceptional in sand and soft mud; wide flat flukes bury deep under load
Weakness: Skips on top of grass, kelp, and rock; can foul if direction reverses sharply
Typical Weight: Lightweight for holding power — 8–22 lbs covers most recreational vessels
Holding: Good all-around; resets quickly when direction changes
Weakness: Difficult to stow flat; lower holding power per pound than Danforth in soft bottoms
Typical Weight: Similar to CQR; 11–33 lbs typical range for cruising use
Holding: Excellent once buried over time in mud; poor holding when first deployed
Weakness: Useless for temporary anchoring — requires weeks to months to embed fully
Typical Weight: Very heavy — 25–5,000+ lbs used for permanent mooring installations
Holding: Moderate — used to control position, limit swing, or haul a grounded vessel off
Weakness: Not sized for primary anchoring duty; secondary role only
Typical Weight: Typically lighter than main anchor — carried to deploy by dinghy if needed
Windlass: an electric or manual anchor windlass is the mechanical device on the bow used to deploy and retrieve the anchor and chain. The windlass gypsy (or wildcat) grips the chain; the drum handles rope rode. Always keep fingers clear of the gypsy when chain is running — the chain moves rapidly and cannot be stopped instantly.
The choice of anchor rode material affects scope requirements, catenary behavior, holding power, and shock absorption.
Scope is the ratio of rode paid out to the vertical distance from the bow chock to the seabed. Getting this calculation right is essential on the exam and on the water.
Scope Formula
Scope = Rode Length ÷ (Depth + Freeboard)
Freeboard = height of bow chock above waterline. For scope ratios, solve for rode length: Rode = Ratio × (Depth + Freeboard).
Measure Water Depth
Use the depth sounder to read the depth at the anchoring spot. This is the depth from the transducer to the bottom — add 1–2 feet if the transducer is below the waterline.
Add Freeboard at the Bow
Measure the height of your bow chock or hawsehole above the waterline. This is typically 2–6 feet on most recreational vessels. Add this to the water depth.
Choose Scope Ratio
All-chain rode: 5:1 minimum (calm), 7:1 in moderate conditions, 10:1 in heavy weather. Rope or mixed rode: 7:1 minimum, 10:1 in moderate, more in severe conditions.
Calculate Rode Length
Multiply (depth + freeboard) by your scope ratio. Example: 15 ft depth + 4 ft freeboard = 19 ft total. At 7:1 scope: 19 x 7 = 133 ft of rode needed.
Calculate Swinging Room
Swinging room radius equals the rode length plus the vessel length. In 133 ft of rode with a 35 ft vessel, the swinging circle has a 168 ft radius — a 336 ft diameter. Verify this clears other vessels and hazards in all directions.
Catenary is the natural sag curve formed by the weight of chain hanging between the anchor and the bow. This curve accomplishes two things: (1) it keeps the pull angle on the anchor shank nearly horizontal, which maximizes holding power; and (2) the curve straightens before the anchor is lifted, acting as a buffer against sudden jerks from wave action.
Nylon rope has no catenary effect because it is light and stretches tight. It relies on its elasticity for shock absorption. In heavy weather, nylon stretches and recoils — this is effective but requires more scope to keep the pull angle low.
The seabed type determines both anchor selection and how much scope you need. Check the nautical chart — the bottom symbol appears as abbreviations: S (sand), M (mud), Rk (rock), Wd (weed/grass), Co (coral).
Best Anchors: Danforth, CQR, Bruce
Avoid: Nothing in particular — sand accepts most anchors well
Scope: 7:1 nylon; 5:1 chain in calm; increase in wind
The best anchoring substrate. Flukes or plows dig in easily. Good catenary develops with chain.
Best Anchors: Danforth, CQR — flukes embed deeply
Avoid: Bruce can have trouble penetrating very soft mud
Scope: 7:1 to 8:1 — mud provides less initial resistance; more scope compensates
Good holding once set but anchor may be difficult to break out. Mud coats the rode and deck.
Best Anchors: Grapnel — the only anchor designed to hook rock
Avoid: Danforth — flukes cannot penetrate; CQR may foul; all anchors can foul badly
Scope: Maximum scope and chain leader essential to keep rode angle low
Rock is the worst holding ground. Anchor can be permanently fouled. Dive to set if possible. Mark trip line.
Best Anchors: Heavy CQR or Bruce — weight helps punch through vegetation
Avoid: Danforth — skips on top; flukes cannot penetrate the mat
Scope: Use maximum scope and confirm set with a stern load before relying on the anchor
Grass holds the anchor on top rather than letting it set. Back down hard and confirm the anchor is set, not just resting on the mat.
Best Anchors: Sand patches within the coral field if available
Avoid: All anchors damage coral — this is a legal and environmental concern in many jurisdictions
Scope: Sand patch anchoring follows normal sand rules; keep the rode short to stay in the patch
Anchoring on live coral is prohibited in many marine sanctuaries. Use designated moorings. If you must anchor, find a sand patch and use a trip line.
Proper anchoring technique is methodical. Skipping steps — especially backing down to confirm the set — is the primary cause of anchors that appear set but drag at 2 a.m.
Deploying more than one anchor allows the skipper to limit swinging, increase holding power, or control vessel position in tight or exposed anchorages. The OUPV exam tests both the names and procedures of these techniques.
Use When: Reversing tidal currents; tight anchorages where swinging room is limited
Procedure: Drop first anchor upcurrent. Motor downcurrent paying out double scope. Drop second anchor. Take up first rode until vessel rides between the two anchors with equal scope.
Result: Vessel swings in a small oval rather than a full circle. Both anchors always load along the current axis.
Use When: Poor holding ground; severe weather requiring maximum holding power on one bearing
Procedure: Deploy primary anchor normally. Attach a second anchor to the end of the primary rode or via a short shackle, several fathoms behind the primary anchor. Both anchors load in tandem.
Result: Combined holding power of both anchors in one direction. No benefit if direction changes significantly.
Use When: Anchorages exposed to wind from multiple directions; open roadsteads
Procedure: Drop anchors at 45 degrees off each bow, spaced 60–90 degrees apart. Each rode leads to the bow from a different angle. Both load simultaneously when wind swings.
Result: Broader coverage area than a single anchor. Vessel cannot swing fully — provides good directional stability.
Use When: Tight marinas with stern-to docking (common in Europe and the Caribbean)
Procedure: Drop anchor off the bow while approaching the dock stern-first. Back to the dock. Secure stern lines to dock cleats. Tension the anchor rode to hold the bow off the dock.
Result: Stern accessible from the dock; anchor keeps bow from swinging into neighboring vessels.
A dragging anchor is one of the most dangerous situations at anchor. Early detection and rapid response prevent grounding. The exam tests all three areas: recognition, cause, and procedure.
COLREGS Rule 30 governs lights and shapes for anchored vessels. These appear on nearly every OUPV exam. Know them cold.
| Situation | By Day | By Night | Rule |
|---|---|---|---|
| Vessel at anchor under 50 meters | One black ball shape displayed forward | One all-round white light displayed forward where best seen | COLREGS Rule 30(a) |
| Vessel at anchor 50 meters or more | One black ball shape displayed forward | All-round white forward AND all-round white aft — aft light lower than forward | COLREGS Rule 30(a)(i) and (ii) |
| Vessel at anchor — additional for large vessels | N/A | May use deck lights to illuminate decks to make themselves more conspicuous | COLREGS Rule 30(d) |
| Vessel aground | Three black balls in a vertical line forward | Anchor light(s) PLUS two all-round red lights in a vertical line | COLREGS Rule 30(d) and (e) |
Exam Tip
Vessels at anchor are NOT required to show a black ball in any anchorage — they must show it where it can best be seen from any direction. The exam often asks whether a specific vessel must show an anchor light or shape. Vessels under 7 meters anchored outside a fairway are not required to show anchor lights if impractical.
Federal anchorage regulations establish where vessels may and may not anchor in US navigable waters. The OUPV exam tests both the existence of these regulations and the authority behind them.
Regulated Anchorages — General
33 CFR Part 110 designates specific anchorage areas throughout US navigable waters. Anchoring outside a designated area, in a fairway, or in a traffic separation scheme is restricted or prohibited.
Exam: Vessels must anchor in designated anchorages when available and directed. Anchoring in a fairway obstructs traffic.
Anchorage Permits
Some regulated anchorages require a permit from the COTP (Captain of the Port). Commercial vessels and foreign vessels are more likely to need permits. Recreational vessels generally have fewer permit requirements but must still use designated areas.
Exam: Know that the COTP administers anchorage regulations. Permission from COTP is the authority in regulated areas.
Duration Limits
Many anchorage areas have time limits — 24 hours, 72 hours, or one week depending on the area. Overstaying an anchorage limit is a violation subject to citation. Check the Local Notice to Mariners for current rules.
Exam: Duration limits exist in some anchorages. Always check LNMM and the chart for current restrictions.
Restricted Areas
Anchoring is prohibited in many areas including: active shipping channels, safety zones around bridges and facilities, security zones near military or government vessels, cable and pipeline areas marked on charts.
Exam: Cable areas are marked on charts and anchoring is prohibited. Anchoring over a power cable can destroy the anchor and the cable.
Emergency Exception
A vessel may anchor outside designated areas in a genuine emergency — engine failure, medical emergency, extreme weather. The vessel should notify the USCG and move as soon as conditions permit.
Exam: The emergency exception exists but the vessel must move out of the restricted area as soon as able.
A mooring buoy provides a fixed attachment point without the need to anchor. The buoy connects to a permanent anchor or ground tackle on the seabed — sized to hold the vessels it serves. Picking up a mooring properly protects the vessel, the buoy, and the mooring system.
Identify the Buoy
Confirm the buoy is a designated mooring, not a navigational aid or private mark. White mooring buoys with a blue horizontal band are the standard in the US. Check the chart and cruising guide for holding capacity.
Approach Slowly
Approach into the wind or current — whichever is stronger — at bare steerage. Stop the vessel with the bow just short of the buoy. Never approach at speed near a mooring field.
Pick Up the Buoy
Use a boat hook to catch the buoy pick-up line (a small line hanging from the buoy) or the buoy itself. Bring the pennant line aboard through the bow chock — never over the lifelines.
Secure with Pennant Lines
Pass the mooring pennant through the bow chock and secure to the bow cleat with a cleat hitch. For overnight stays, use two pennant lines to separate cleats for redundancy.
Install Chafing Gear
Wherever the pennant line passes through a bow chock, wrap it with chafing gear — a section of hose, leather, or heavy cloth. At anchor or on a mooring, chafe is the primary cause of rode or pennant failure overnight.
Confirm the Mooring
Take a range on fixed objects. Ensure the mooring pennant is not fouling the keel or rudder. Check that you will not swing into other vessels or hazards as wind and current shift.
The OUPV exam tests marlinspike seamanship in two ways: identifying which knot to use for a given purpose, and knowing how to tie the bowline. All six knots below appear in USCG question banks.
Use: Fixed loop that will not slip; attaching lines to rings, pilings, and safety harnesses
How: The rabbit comes out of the hole, goes around the tree, back down the hole
Strength: Retains approximately 65–70% of line strength
Release: Easily untied after loading — push the standing part to collapse the knot
Use: Securing a line to a cleat — dock lines, anchor rode, mooring pennant
How: Full turn around the base, figure-8 across the horns, locking half-hitch to finish
Strength: As strong as the line when properly tied to a through-bolted cleat
Release: Quick release by removing the half-hitch and unwrapping
Use: Temporarily securing a line to a piling or ring; fender lines; adjustable position
How: Two half-hitches in the same direction with the end passed under the second wrap
Strength: Can slip under sustained load — not for permanent use
Release: Instantly adjustable — slide up or down the piling
Use: Stopper knot — prevents a line from running through a block, fairlead, or clutch
How: Over and under — the working end makes a figure-8 pattern
Strength: Does not reduce line strength significantly; easy to inspect
Release: Can be difficult to untie after heavy loading — use reef knot for joining instead
Use: Joining two lines of equal diameter; tying sail reefing points; bundling gear
How: Right over left, left over right — or: left over right, right over left
Strength: Only secure when both lines are of equal size; jams under severe load
Release: Capsizes into two slip knots when ends are pulled apart — quick release
Use: Securing a line to another line under tension; attaching a snubber to an anchor chain
How: Two wraps in the direction of load, then a half-hitch on the opposing side
Strength: Grips tightly in the direction of load; the more load, the tighter it grips
Release: Releases easily when load is removed
Splices create permanent connections that retain near-full line strength. Whipping seizes the end of a line to prevent unraveling. Both appear in OUPV exam question sets.
Use: Permanent fixed loop in the end of braided or three-strand line
How: Unlay the strands 4–6 inches. Tuck each strand over and under the standing part strands at least three times. Pull tight, roll to fair, trim tails.
Use: Joining two lines permanently — increases diameter at the splice
How: Unlace both ends 4–6 inches. Interlock the strands alternately. Tuck each strand over-under at least three times on both sides.
Use: Seizing the end of a line to prevent unraveling; does not require a needle
How: Middle a length of whipping twine. Tie a half-hitch forward, half-hitch aft, alternate until the whipping is one line diameter long. Finish with a reef knot on the back side.
Use: The most secure permanent whipping — used with a needle and palm
How: Pass twine through a strand. Spiral the twine toward the rope end. Bring twine back through the strand grooves. Finish with a reef knot inside the lay. Trim flush.
Spring lines are the most versatile docking lines aboard. They control fore-and-aft movement and are used to depart a berth using engine power rather than manual effort.
Runs from the bow aft to a dock cleat amidships or aft. Prevents the vessel from moving forward.
Hold position when current or wake pushes you forward. Used to pivot the stern away from the dock when departing.
Runs from the stern forward to a dock cleat amidships or forward. Prevents the vessel from moving astern.
Hold position when current or wake pushes you aft. Used to pivot the bow away from the dock when departing.
Runs from the bow perpendicular to the dock face. Holds the bow close to the dock.
Positioning and short-term security. Limits perpendicular movement but does not prevent fore/aft movement.
Runs from the stern perpendicular to the dock face. Holds the stern close to the dock.
Positioning and short-term security. Works with the bow breast line to hold the hull parallel to the dock.
Departing with a Spring Line
To pivot the stern away from a port-side berth: secure the bow spring (forward spring) to a dock cleat. Put the engine in forward with starboard helm. The stern swings away from the dock. Cast off the spring and back away cleanly.
To pivot the bow away from a port-side berth: secure the stern spring (after spring) to a dock cleat. Put the engine in reverse with starboard helm. The bow swings out from the dock. Cast off the spring and go ahead.
Prop walk is the sideways movement of the stern caused by the propeller rotating in water. On a right-hand propeller — the standard on most single-screw vessels — the stern walks to port in reverse. This is the most tested single-screw handling concept on the OUPV exam.
Stern movement: Slight starboard walk — usually negligible at normal ahead speeds
Helm effectiveness: Steerable with rudder; prop walk in forward is minimal
Stern movement: Strong PORT walk — the stern kicks to port
Helm effectiveness: Rudder is largely ineffective in reverse at slow speeds; prop walk dominates
Stern movement: Brief forward kick, then strong port walk in reverse
Helm effectiveness: Short bursts alternating forward and reverse allow steering without much way on
Rule 9 governs vessel conduct in narrow channels and fairways. It is one of the most frequently tested COLREGS rules on the OUPV exam — the language is specific and the distinctions matter.
Keep to Starboard
Every vessel shall keep as far to the starboard side of the channel as is safe and practicable
Same as road traffic — stay right
Small Vessels Must Not Impede
Vessels under 20 meters or sailing vessels shall not impede vessels that can only safely navigate within the channel
Small boats yield to deep-draft vessels — a sailboat cannot force a tanker to stop
Fishing Vessels Must Not Impede
Vessels engaged in fishing shall not impede other vessels navigating in a narrow channel
Fishing does not grant right of way in a channel — even if gear is deployed
No Crossing if It Impedes
A vessel shall not cross a narrow channel if doing so impedes a vessel that can only navigate within it
Do not cut across a channel when a ship is coming through — wait for it to pass
Bend Signal
A vessel nearing a bend where another vessel may be hidden shall sound one prolonged blast
Announcing your approach around a blind corner
Traffic Separation Schemes
Traffic separation schemes (TSS) are designated traffic lanes in busy shipping areas. COLREGS Rule 10 governs conduct in a TSS. Vessels using a TSS shall: join or leave at the ends if practicable; avoid crossing if possible; if crossing, do so as nearly as practicable at right angles to the general direction of traffic flow; not impede the safe passage of a power-driven vessel following a traffic lane.
A vessel not using a TSS shall avoid it by as wide a margin as practicable. Fishing vessels, sailing vessels, and vessels under 20 meters must not impede the safe passage of power-driven vessels in a traffic lane.
These six concepts appear on nearly every OUPV exam in this subject area. Know them precisely, including the numbers and the specific language.
Scope is based on depth PLUS freeboard — not depth alone
The most common scope calculation error. Scope ratio applies to the entire distance from bow chock to seabed — that includes the height of the bow above the waterline. In 15 ft of water with 4 ft of freeboard, you need 7 x 19 = 133 ft of rode, not 7 x 15 = 105 ft. The exam will test this exact calculation.
Prop walk in reverse goes to PORT on a right-hand propeller
Memorize: right-hand prop in reverse, stern goes to port. This is the single most testable single-screw vessel handling concept. Use it intentionally: back to a port-side dock and let prop walk bring the stern in. Trying to back to a starboard-side dock takes more skill because you are working against prop walk.
Bahamian moor vs. tandem anchors — know the difference
Bahamian moor: two anchors deployed in opposite directions, vessel between them — limits swinging in a tidal current. Tandem anchors: two anchors on one rode in the same direction — doubles holding power but only in one direction. Both appear on the OUPV exam. The question often gives you the deployment description and asks you to name the technique.
Anchored vessels display a black BALL by day, white LIGHT by night
COLREGS Rule 30: an anchored vessel under 50 meters shows one black ball forward by day, one all-round white light forward by night. Vessels 50 meters or more add a second all-round white light aft (lower than forward). A vessel aground adds two red lights at night and three black balls by day. These are heavily tested.
Rolling hitch for the snubber — not a clove hitch
Attaching a nylon snubber to an anchor chain requires a rolling hitch, not a clove hitch. The rolling hitch grips tighter as load increases and will not slide along the chain. A clove hitch will slip under sustained load. The exam asks which knot is used to attach a snubber to anchor chain.
COLREGS Rule 9: small vessels must not impede, not merely yield
The language in Rule 9 is must not impede — a stronger obligation than ordinary stand-on/give-way rules. A vessel under 20 meters must take positive early action to stay clear of a vessel that can only navigate within the channel. Waiting until the last moment and then yielding may still be a violation if you impeded the other vessel.
These questions are written in the style and difficulty of actual USCG OUPV exam questions. Work through each one before reading the answer.
A vessel is anchored in 20 feet of water. The bow chock is 3 feet above the waterline. For a nylon rode in normal conditions, how much rode should be deployed?
Answer
Total depth = 20 + 3 = 23 feet. At 7:1 scope: 23 x 7 = 161 feet. Round up to the nearest 5 or 10 feet — deploy approximately 165 feet of rode.
A single-screw vessel with a right-hand propeller is docking port-side-to. The skipper puts the engine in reverse to stop. What happens to the stern?
Answer
The stern walks to port — toward the dock. This is prop walk on a right-hand propeller in reverse. A skilled skipper uses this to bring the stern neatly to the port-side dock without spring lines.
Which knot is used to attach a nylon snubber to an anchor chain under load?
Answer
Rolling hitch. It grips tighter as load increases and will not slide along the chain. A clove hitch is incorrect — it will slide under sustained load.
What light does an anchored vessel under 50 meters show at night?
Answer
One all-round white anchor light, displayed forward where it can best be seen. COLREGS Rule 30. Vessels 50 meters or more also show a second all-round white light aft, lower than the forward light.
A vessel approaching a bend in a narrow channel where another vessel may be hidden should sound what signal?
Answer
One prolonged blast, per COLREGS Rule 9(f). The approaching vessel from the other side should also sound one prolonged blast in response.
A Danforth anchor is deployed in a grassy bottom. The vessel sets the anchor but it begins dragging as soon as wind picks up. What is the most likely cause?
Answer
The Danforth flukes cannot penetrate the grass mat. They are resting on top of the vegetation and have no holding power. A heavier CQR or Bruce anchor with more weight to punch through the mat would be more effective. More scope alone will not solve the problem.
What is the purpose of a trip line on an anchor?
Answer
A trip line is attached to the crown of the anchor and led to a float on the surface. If the anchor fouls on debris, chain, or rock, the trip line allows you to pull the anchor free from the crown end — the opposite direction from normal retrieval. Without a trip line, a fouled anchor in rock or on debris may require a diver to free it.
A vessel is executing a Bahamian moor. After dropping the second anchor, what is the next step?
Answer
Haul in (take up) the first anchor rode until the vessel is positioned between the two anchors with approximately equal scope on each. The vessel should end up riding between the two anchors with the rode from each leading out at roughly equal angles.
These techniques are used by experienced mariners. They are not always in the textbook — but they appear in exam scenarios and are essential for practical seamanship.
The Compass Bearing Technique
After setting the anchor, take compass bearings on two fixed objects at roughly 90 degrees to each other. Note the bearings. If they change, you are dragging. This is the fastest way to detect dragging without a GPS alarm.
The Hand on the Rode Test
With chain rode, place your hand on the chain near the bow chock while backing down. Steady tension means the anchor is holding. Grinding and bumping vibration means the anchor is dragging along a hard bottom. Silence with no tension means the anchor is not set at all.
Anchoring Like the Locals
Anchor near vessels of similar type. A monohull and a multihull respond to wind and current differently and will swing in different arcs. Anchor near vessels that will swing the same way you do to avoid collisions at 2 a.m. when the wind shifts.
The Snubber is Not Optional
On chain rode, a nylon snubber is essential. Without it, every wave transmits a sharp jerk directly to the windlass through rigid chain. Over time, this damages the windlass, cracks bow fittings, and stresses the hull. Attach the snubber with a rolling hitch, let out enough chain to put slack in it, and let the snubber take all the load.
Mediterranean Moor: Back In Slowly
When executing a Mediterranean moor, the key is slow and controlled. Drop the anchor while 2–3 boat lengths off the dock, then back in slowly. Too fast and you will overrun the chain. Too slow and you will not have enough momentum to reach the dock. Brief the crew: one person on the windlass, one on the stern lines, helm watching both.
Set a GPS Anchor Alarm
Modern chartplotters allow you to set an anchor alarm — a circle of a specified radius around your anchored position. If the vessel moves outside the circle, the alarm sounds. Set it to your swinging circle radius. This does not replace visual watches in poor holding, but it provides reliable detection when you sleep.
Scope is the ratio of rode length to depth of water measured from the bow chock to the seabed. The formula is: scope = rode length divided by (depth + freeboard at bow). For all-chain rode in calm conditions, 5:1 scope is the minimum. For nylon rope rode in normal conditions, use 7:1. In severe weather, increase to 10:1 or more. Example: in 15 feet of water with 4 feet of freeboard, total depth is 19 feet. At 7:1 scope you need 133 feet of rode. Always err on the side of more scope — dragging is far more dangerous than swinging wide.
The Danforth (fluke-style) anchor excels in sand and mud. Its wide, flat flukes dig in aggressively as load is applied and develop very high holding power per pound of anchor weight. The CQR/plow also performs well in sand and is a good all-around choice. The Bruce/claw anchor is good in sand but less effective than a Danforth at maximum holding. In rock, no anchor holds well — use a lunch hook or prepare to free-dive to set it. In grass, a Danforth often skips on top; a heavier CQR or Bruce has better penetration.
Signs of a dragging anchor include: (1) landmarks or ranges going out of alignment — the most reliable visual check; (2) depth sounder showing changing depth; (3) GPS track showing movement downwind or down-current; (4) feeling a rumbling or bumping sensation transmitted up the rode, especially with chain on rock; (5) the rode going slack then snapping taut in a jerky pattern instead of holding steady tension. At night: watch your anchor light relative to other anchored vessels. Any change in bearing to fixed objects means you are dragging.
Prop walk is the tendency of a propeller to walk the stern sideways — in addition to providing thrust. A right-hand propeller (most common) in forward gear walks the stern slightly to starboard. In reverse gear, the stern walks strongly to port. This asymmetry is why a single-screw vessel backs to port more easily than to starboard. Skippers use prop walk intentionally: when docking port-side-to, back down to bring the stern neatly to the dock. When departing from the port side, a brief burst of reverse helps kick the stern away. Understanding prop walk is essential for the OUPV practical assessment and exam questions on vessel handling.
COLREGS Rule 9 — the Narrow Channel Rule — requires: (1) vessels shall keep as far to the starboard side of the channel as is safe and practicable; (2) vessels under 20 meters or sailing vessels shall not impede vessels that can only navigate safely within the channel; (3) vessels fishing shall not impede other vessels navigating in a narrow channel; (4) a vessel shall not cross a narrow channel if doing so impedes a vessel that can only navigate within it; (5) a vessel overtaking another in a narrow channel must indicate the intention using sound signals; (6) a vessel nearing a bend where other vessels may be obscured shall sound one prolonged blast. Failing to keep to the right in a channel is a common exam scenario.
The bowline creates a fixed loop that will not slip under load and is easily untied after loading. Remember the mnemonic: the rabbit comes out of the hole, goes around the tree, and goes back down the hole. To tie: (1) form a small loop in the standing part with the working end on top; (2) pass the working end up through the small loop from underneath — this is the rabbit coming out; (3) pass the working end around behind the standing part — going around the tree; (4) bring the working end back down through the small loop — back into the hole; (5) dress and set the knot by pulling the standing part and working end. The bowline is used to attach lines to rings, cleats, and pilings, and for safety harnesses. It is one of the most tested knots on the OUPV exam.
An anchored vessel displays: a white all-round anchor light forward (visible from all directions), and on vessels 50 meters or more in length, an additional white all-round light aft, lower than the forward light. In daytime, a black ball shape is displayed forward where it can best be seen. These requirements are in COLREGS Rule 30. Vessels under 7 meters anchored outside a fairway or anchorage where other vessels navigate are not required to show anchor lights or shapes, but must do so if practical. Failure to show proper anchor lights is a COLREGS violation and a common exam question.
The Bahamian moor uses two anchors deployed off the bow in opposite directions along the current or tide axis. It limits the vessel to swinging in a small circle rather than the full 360-degree swing of a single anchor. Procedure: (1) motor upcurrent and drop the first anchor; (2) pay out double the normal scope while motoring downcurrent; (3) drop the second anchor; (4) take up the first rode until both are equalized with the vessel between them. The Bahamian moor is ideal in areas with reversing tidal currents, tight anchorages, or where swinging room is limited. It is tested on the OUPV exam under multiple anchor techniques.
NailTheTest generates unlimited USCG-style anchoring and seamanship questions — scope calculations, anchor selection, prop walk, Rule 9, and marlinspike seamanship — with immediate explanations for every answer.
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