OUPV Vessel Seamanship and Maneuvering 2 — Questions and Answers
Question 1: What effect does prop walk have on a single-engine vessel when going astern?
- The stern moves toward the direction of propeller rotation (Correct answer)
- The bow dips below the waterline
- The vessel speeds up
- There is no effect when going astern
Correct answer: The stern moves toward the direction of propeller rotation
Prop walk causes the stern to move in the direction the bottom of the propeller is rotating when in reverse, typically to port on a right-hand rotation propeller.
Prop walk occurs because the lower propeller blade operates in denser water, generating more thrust than the upper blade. On a standard right-hand rotation propeller, the bottom blade moves to port in reverse, pushing the stern to port.
Question 2: What is the proper technique for approaching a dock in a crosswind pushing toward the dock?
- Approach at full speed perpendicular to the dock
- Approach at a shallow angle, slow, and let the wind push the vessel alongside (Correct answer)
- Always approach against the wind
- Approach stern-first regardless of conditions
Correct answer: Approach at a shallow angle, slow, and let the wind push the vessel alongside
When the wind is pushing toward the dock, approach at a shallow angle at slow speed, allowing the wind to set the vessel alongside gently.
When docking with wind pushing toward the dock, approach at a shallow angle (10-20 degrees) at minimum steerage speed. The wind will help push the vessel alongside. Get the upwind bow line secured first.
Question 3: What is the turning circle of a vessel?
- The diameter of the helm wheel
- The path traced by a vessel from the time the rudder is put hard over until it returns to its original heading (Correct answer)
- The radius of the propeller
- The length of the vessel
Correct answer: The path traced by a vessel from the time the rudder is put hard over until it returns to its original heading
The turning circle is the circular path traced by a vessels pivot point when the rudder is put hard over.
The turning circle describes the path a vessel follows during a 360-degree turn with maximum rudder deflection. Key measurements include advance, transfer, tactical diameter (typically 3-4 vessel lengths), and final diameter. The turning circle increases with speed.
Question 4: How does trim affect a vessels handling characteristics?
- Trim has no effect on handling
- Bow-heavy trim improves directional stability but reduces maneuverability; stern-heavy trim increases maneuverability but reduces stability (Correct answer)
- Only affects fuel consumption
- Only matters for vessels over 100 feet
Correct answer: Bow-heavy trim improves directional stability but reduces maneuverability; stern-heavy trim increases maneuverability but reduces stability
Trim significantly affects handling: bow-down trim tracks straighter but turns slowly; stern-down trim turns more easily but may be less directionally stable.
Bow-down trim increases underwater surface area forward, improving tracking but making turns wider. Stern-down trim shifts more hull area aft, making the vessel more responsive to helm input. Most planing hulls are designed to run slightly stern-down.
Question 5: What is the danger of following seas (waves from astern)?
- They cool the engine
- Risk of broaching, pooping (waves breaking over the stern), or surfing out of control (Correct answer)
- They always increase vessel speed safely
- There is no danger from following seas
Correct answer: Risk of broaching, pooping (waves breaking over the stern), or surfing out of control
Following seas can cause broaching, pooping, or surfing down wave faces with loss of steering control.
Following seas present several dangers: broaching (stern pushed sideways, beam-to waves), pooping (waves break over transom), pitchpoling (bow digs in while stern lifts), and surfing (vessel accelerates uncontrollably down wave face). Prevention includes reducing speed and using a drogue.
Question 6: What is the proper procedure for passing through a narrow channel?
- Navigate at maximum speed
- Keep to the starboard side of the channel, maintain safe speed, and be prepared for meeting traffic (Correct answer)
- Navigate in the center at all times
- Pass through only at slack tide
Correct answer: Keep to the starboard side of the channel, maintain safe speed, and be prepared for meeting traffic
In narrow channels, vessels must keep to the starboard side, maintain safe speed, and be alert for oncoming traffic.
Rule 9 governs narrow channel navigation: keep to starboard as far as safe and practicable. Do not cross the channel if it would impede others. Sound one prolonged blast when approaching a blind bend. Reduce speed to minimize wake.
OUPV Vessel Seamanship and Maneuvering 2
What effect does prop walk have on a single-engine vessel when going astern?