OUPV Vessel Seamanship and Maneuvering 3 — Questions and Answers
Question 1: What is the pivot point of a vessel and why is it important for maneuvering?
- The center of the vessel at all times
- The point around which the vessel rotates, typically forward of amidships when moving ahead (Correct answer)
- The location of the rudder
- The bowsprit
Correct answer: The point around which the vessel rotates, typically forward of amidships when moving ahead
The pivot point is typically located about one-third from the bow when moving ahead. Understanding it is critical for close-quarters maneuvering.
When moving ahead, the pivot point is about 1/4 to 1/3 from the bow, meaning the stern swings wide. When moving astern, it shifts to about 1/4 to 1/3 from the stern, causing the bow to swing wide. Essential for tight maneuvering.
Question 2: How does shallow water affect a vessels handling?
- No effect on modern vessels
- Increased squat, reduced rudder effectiveness, longer stopping distance, and possible bank effect (Correct answer)
- The vessel handles better in shallow water
- Only affects sailboats
Correct answer: Increased squat, reduced rudder effectiveness, longer stopping distance, and possible bank effect
Shallow water causes squat, reduced rudder response, increased stopping distance, and bank suction effects.
Shallow water effects become significant when depth is less than about twice the vessels draft. Effects include: squat (vessel sinks deeper at speed), reduced rudder effectiveness, increased stopping distance, vibration, and bank effect (suction toward nearby banks). Speed reduction is the primary countermeasure.
Question 3: What is the purpose of a spring line when departing a dock?
- To pull the vessel straight off the dock
- To use as a pivot point to swing the bow or stern away from the dock using engine power (Correct answer)
- To tow another vessel
- To secure the anchor
Correct answer: To use as a pivot point to swing the bow or stern away from the dock using engine power
During departure, a spring line can be used as a pivot point. By applying engine power against the spring, the bow or stern swings away from the dock.
Spring line departure technique: single up to one spring line, place a fender at the pivot point, engage gear with rudder toward the dock, and the opposite end swings out. When sufficient angle is achieved, release the spring and proceed.
Question 4: What is lee helm and when is it dangerous?
- A tendency for the vessel to turn away from the wind, requiring constant correction (Correct answer)
- Steering from the protected side of the vessel
- A type of emergency tiller
- A method of anchoring
Correct answer: A tendency for the vessel to turn away from the wind, requiring constant correction
Lee helm is a vessels tendency to turn away from the wind. It is dangerous because if the helm is released, the vessel turns beam-to the wind and waves.
Lee helm occurs when a vessel naturally tends to turn to leeward. This is dangerous because if the operator loses grip on the helm, the vessel turns beam-to the seas, the most vulnerable orientation for capsize. Weather helm (tendency to turn into wind) is considered safer.
Question 5: How should a vessel approach a person in the water for recovery?
- At full speed directly toward them
- Approach slowly from downwind/downcurrent, keeping the person on the lee side to provide shelter (Correct answer)
- Approach from upwind at maximum speed
- Circle continuously until Coast Guard arrives
Correct answer: Approach slowly from downwind/downcurrent, keeping the person on the lee side to provide shelter
The recovery approach should be from downwind/downcurrent with the person on the vessels lee side, which provides calmer water and prevents drift onto the person.
Standard MOB recovery: maneuver to approach from downwind/downcurrent at slow speed, position the person on the lee side so the vessel drifts away not onto them, stop engines before the person is alongside to prevent propeller injury, and use a ladder or lifting device.
Question 6: What is the effect of adding weight above a vessels center of gravity?
- Increases stability
- Raises the center of gravity, decreasing stability and increasing the risk of capsize (Correct answer)
- No effect on stability
- Improves fuel efficiency
Correct answer: Raises the center of gravity, decreasing stability and increasing the risk of capsize
Adding weight above the center of gravity raises it, reducing the vessels righting moment and making it more prone to capsizing.
A vessels stability depends on the relationship between center of gravity (G) and center of buoyancy (B). Weight above G raises it, reducing metacentric height (GM) and righting moment. This makes the vessel tender and more susceptible to capsize. Keep heavy items low.
OUPV Vessel Seamanship and Maneuvering 3
What is the pivot point of a vessel and why is it important for maneuvering?