Ch. 2 Flashcards
To break a sheer in a narrow channel a pilot should
Increase engine revolutions
Increase rudder toward the bank
Your vessel is steaming parallel to a shoal or bank. How does she behave?
Her bow will move away from the bank or shoal
Her stern moves toward the bank or shoal
T or F Competent shiphandlers don’t just react. They think ahead, anticipate situations, and plan alternative maneuvers
True
T or F Ships with variable pitch propellers steer best if speed is reduced quickly?
False
Advantages of omnidirectional propulsion systems over conventional systems include.
greater safety
increased maneuverability
T or F Shiphandlers should re-evaluate any maneuver requiring repeated use of the engine or thrusters at half ahead and full power
True
T or F When steering using azipods in the at sea mode the pod is turned to port to turn the ship to starboard?
True
Although azipods may be placed in virtually any position, there are three positions that have been found to be most effective in practical use. They are
At sea mode - used in open waters
Harbor mode - used in narrow channels
Docking mode - used as ship approaches the berth
When operating in harbor mode, the pods are placed at 45 degrees in opposition to each other. The vessel is turned to port by moving the ______ control ahead and pulling back on the ______ control.
starboard, port
A good rule of thumb to change from automatic to manual control is within ______ from a fixed object of dock
One ship length
The tactical diameter and turning rate can be adjusted during a turn by visually aligning an external fixed object with a reference point aboard ship
The tactical diameter is decreasing when the object moves ahead relative to the ship reference point
The rate of turn is increasing if the object moves ahead more rapidly
T or F It is best to overtake another ship in a narrow channel at slow speed, while the ovretaken ship should increase her speed before being passed.
False
The clicking sound made by the gyro compass should be eliminated as it distracts the pilot
False
A rate-of-turn indicator usually indicates turning rate in _______ per second or _______ per minute.
Tenths of a degree
degrees per minute
A ship changes draft when moving into shallow water. The change in draft is known as ______. The hull rotation about the transverse axis and resulting change in trim forward or aft is known as _______. The increase in deep draft, forward or aft is called ______.
sinkage, trim, squat
The increasing pressure drop under a hull and the corresponding increase in squat caused by water flowing under the hull at increased velocity as ship’s speed increases, follows a basic principle of physics known as the ___________ Principle
bernoulli
T or F Ships always tim by the stern in shallow water?
False
The pilot or ship’s officer can reduce sinkage and squat by reducing the ________.
Speed and the rate and period of acceleration
Squat for a given speed and hull condition in confined water is ________ that in open water.
Twice
A useful formula for calculating approximate sinkage in open waters is ________
Squat (feet) = block coefficient x (speed in knots)^2/30
for shallow water multiply the squat found by 2
UKC is influenced by several factors including
Speed
Channel dimensions
changes in engine revs
vessel interaction
UKC is reduced significantly when two ships pass in a narrow channel because squat increases _______% to _____% or even more depending on ships speed and distance of separation
50% to 60%
up to 100% or more
UKC is reduced signifcantly as the ship accelerates and squat increases as much as _______%
Double
T or F Wide beam ships increase draft significantly when they roll, so rolling may have a greater impact on UKC than draft.
True
T or F Changes in the shape of a channel have no affect on squat as long as the blockage factor does not change
False
If block coefficient is greater then ___ likely to trim by the head. If block coefficient is greater less than ____ likely to trim by the stern.
.75
.7
