Shiphandling Flashcards
Which of the following statements accurately describes the relative properties of water and air?
A) Water is 850 times denser than air and 100 times more viscous than air.
B) Water is 100 times denser than air and 850 times more viscous than air.
C) Water is 100 times denser than air and 100 times more viscous than air.
D) Water is 850 times denser than air and 850 times more viscous than air.
A) Water is 850 times denser than air and 100 times more viscous than air.
Which statement accurately reflects the behavior of pressure in a stream?
A) Total pressure decreases as dynamic pressure increases, resulting in a decrease in static pressure.
B) Total pressure remains constant in a stream, and an increase in dynamic pressure corresponds to a decrease in static pressure.
C) Total pressure increases as dynamic pressure increases, leading to an increase in static pressure.
D) Total pressure fluctuates in a stream, regardless of changes in dynamic pressure and static pressure.
Total pressure remains constant in a stream. If dynamic pressure increases, static pressure
decreases.
Which principle describes the relationship between static pressure and speed change?
A) Static pressure changes linearly with speed change.
B) Static pressure remains constant regardless of speed change.
C) Static pressure changes exponentially with speed change.
D) The change in static pressure is proportional to the square of the speed change.
D) The change in static pressure is proportional to the square of the speed change.
Which statement accurately describes the distribution of static pressure on a ship with headway?
A) A ship with headway experiences low static pressure at the bow and stern, and high static pressure amidships.
B) Static pressure on a ship with headway remains uniform across all sections.
C) A ship with headway experiences high static pressure at the bow and stern, and low static pressure amidships.
D) Static pressure is not affected by the ship’s movement or direction
C. Ship with headway has high static pressure at bow and stern, low static pressure amidships.
Which statement accurately compares the characteristics of turbulent and laminar boundary layers?
A) The laminar boundary layer deepens faster and has a steeper velocity gradient than the turbulent boundary layer.
B) Both turbulent and laminar boundary layers deepen at the same rate but have different velocity gradients.
C) The turbulent boundary layer deepens faster and has a steeper velocity gradient than the laminar boundary layer.
D) Turbulent and laminar boundary layers have identical characteristics in terms of depth and velocity gradient.
a. Turbulent boundary layer deepens faster and has steeper velocity gradient than laminar
boundary layer.
Which relationship correctly matches a dimensionless number with its corresponding resistance in fluid dynamics?
A) Froude number is indicative of wave resistance, while Reynolds number relates to viscous resistance.
B) Froude number represents viscous resistance, and Reynolds number indicates wave resistance.
C) Froude number correlates with both wave and viscous resistances, while Reynolds number denotes no particular resistance.
D) Reynolds number corresponds to wave resistance, while Froude number indicates viscous resistance.
Froude number = wave resistance.
Reynolds number = viscous resistance.
Which statement accurately advises on assessing wind speed onboard?
A) Wind speed should be measured at the highest point on the ship for accuracy.
B) Wind speed should be assessed at sea level to minimize errors.
C) The wind speed reported at 10 meters above sea level is the most reliable onboard measurement.
D) Wind speed should be estimated based on the ship’s speed and direction.
When assessing wind speed, reported 10m wind speed should be used.
Which statement accurately describes the relationship between a ship’s displacement and its hydrodynamic mass?
A) The hydrodynamic mass carried by a ship is typically less than 25% of its displacement.
B) Hydrodynamic mass carried is always greater than 100% of a ship’s displacement.
C) The hydrodynamic mass carried by a ship ranges from 25% to 100% of its displacement.
D) Hydrodynamic mass is unrelated to a ship’s displacement.
Hydrodynamic mass carried is 25% to 100% of ship’s displacement.
Which statement accurately estimates the virtual mass of a ship?
A) Virtual mass is always less than the ship’s displacement.
B) Virtual mass is approximately equal to the ship’s displacement.
C) The virtual mass of a ship typically ranges from 1.3 times to 2 times its displacement.
D) Virtual mass is irrelevant to the displacement of the ship.
The virtual mass of a ship typically ranges from 1.3 times to 2 times its displacement.
Which statement accurately describes the relationship between virtual mass and the ship’s displacement at specific distances from the ship?
A) Virtual mass remains constant regardless of the distance from the ship.
B) Virtual mass increases linearly with the distance from the ship.
C) At a distance of 1.5 times the ship’s diameter (1.5d), virtual mass equals 1.5 times the displacement, and at 1.1 times the diameter (1.1d), it equals 1.8 times the displacement.
D) Virtual mass decreases exponentially as the distance from the ship increases.
C) At a distance of 1.5 times the ship’s diameter (1.5d), virtual mass equals 1.5 times the displacement, and at 1.1 times the diameter (1.1d), it equals 1.8 times the displacement.
Which phenomenon is responsible for the turning effect ahead induced by dissimilar drag on propeller blades?
A) Lift force
B) Drag force
C) Torque
D) Thrust
Turning effect ahead caused by dissimilar drag on propeller blades (torque)
Which factors contribute to the turning effect astern on a vessel?
A) Propeller torque and the force of water against the hull
B) Wind resistance and hull friction
C) Water currents and wave action
D) Buoyancy and propeller rotation
Turning effect astern caused by dissimilar drag on propeller blades (torque) and force of water
against hull (deadwood effect).
What is the primary cause of cavitation in propellers?
A) Formation of bubbles at high-pressure areas and bursting at low-pressure areas.
B) Formation of bubbles at low-pressure areas and bursting at high-pressure areas.
C) Corrosion of the propeller surface due to water exposure.
D) Mechanical failure of the propeller blades.
B) Formation of bubbles at low-pressure areas and bursting at high-pressure
What are the primary locations for cavitation occurrence in propellers?
A) At the root of the propeller blades
B) Along the midsection of the propeller blades
C) At points of high water flow, such as blade tips, and blade thickness, such as the leading edge
D) At the trailing edge of the propeller blades
C) At points of high water flow, such as blade tips, and blade thickness, such as the leading edge
How does cavitation affect propeller thrust, particularly when rapid pitch changes occur on a Variable Pitch Propeller (VPP)?
A) Cavitation has no effect on propeller thrust during pitch changes.
B) Cavitation leads to a gradual change in propeller thrust during pitch changes.
C) Cavitation may cause an abrupt change in propeller thrust if pitch changes occur quickly on a Variable Pitch Propeller (VPP).
D) Cavitation increases propeller thrust during pitch changes on a Variable Pitch Propeller (VPP).
C) Cavitation may cause an abrupt change in propeller thrust if pitch changes occur quickly on a Variable Pitch Propeller (VPP).
What phenomenon describes the occurrence when the upper propeller blade passes close to the water surface?
A) Aeration
B) Cavitation
C) Vibration
D) Erosion
A) Aeration
How does aeration affect the performance of a propeller?
A) Aeration increases thrust and decreases drag.
B) Aeration decreases thrust and increases drag.
C) Aeration has no significant effect on thrust or drag.
D) Aeration increases both thrust and drag.
B) Aeration decreases thrust and increases drag.
How do high skew propellers contribute to the reduction of harmonic vibration?
A) By increasing harmonic vibration
B) By having no effect on harmonic vibration
C) By exacerbating harmonic vibration
D) By smoothing out harmonic vibration
) By smoothing out harmonic vibration
How does increasing the blade area ratio affect vibration and efficiency in propellers?
A) Increasing the blade area ratio decreases vibration and increases efficiency.
B) Increasing the blade area ratio decreases vibration but has no effect on efficiency.
C) Increasing the blade area ratio decreases vibration but decreases efficiency.
D) Increasing the blade area ratio increases vibration and decreases efficiency.
C) Increasing the blade area ratio decreases vibration but decreases efficiency.
Which statement accurately describes the effect of increasing the number of propeller blades on vibration?
A) Increasing the number of propeller blades increases vibration.
B) Increasing the number of propeller blades decreases vibration.
C) Increasing the number of propeller blades has no effect on vibration.
D) Increasing the number of propeller blades decreases efficiency but has no effect on vibration.
B) Increasing the number of propeller blades decreases vibration.
Which statement accurately describes the effect of reducing the number of propeller blades on efficiency?
A) Reducing the number of propeller blades decreases efficiency.
B) Reducing the number of propeller blades has no effect on efficiency.
C) Reducing the number of propeller blades increases efficiency.
D) Reducing the number of propeller blades increases vibration.
C) Reducing the number of propeller blades increases efficiency.
What is a significant factor contributing to the higher efficiency of single screw propellers compared to twin screw propellers?
A) Single screw propellers are smaller in size.
B) Single screw propellers have a simpler design.
C) Single screw propellers are about 20% larger in size.
D) Single screw propellers are about 20% more efficient due to their larger size.
D) Single screw propellers are about 20% more efficient due to their larger size.
How does six months of propeller fouling affect propeller efficiency?
A) It increases efficiency by 8%.
B) It decreases efficiency by 8%.
C) It has no effect on efficiency.
D) It reduces vibration but has no effect on efficiency.
B) It decreases efficiency by 8%.
How does the power requirement for older ships compare to newer ones to achieve the same delivery condition?
A) Older ships require 30% less power.
B) Older ships require 30% more power.
C) There is no difference in power requirements between older and newer ships.
D) Older ships require double the power.
B) Older ships require 30% more power
What is the speed of the flow leaving the rudder relative to the ship’s speed?
A) The same as the ship’s speed
B) Half of the ship’s speed
C) Three times the ship’s speed
D) One-third of the ship’s speed
C) Three times the ship’s speed
What is the effectiveness of the rudder when propulsion is stopped?
A) 100%
B) 75%
C) 53%
D) 25%
C) 53%
At what angle is the rudder most effective?
A) 10°
B) 15°
C) 20°
D) 25°
D) 25°
How is the effectiveness of the rudder distributed between negative and positive pressures?
A) 1/2 due to negative pressure, 1/2 due to positive pressure.
B) 2/3 due to negative pressure, 1/3 due to positive pressure.
C) 1/3 due to negative pressure, 2/3 due to positive pressure.
D) Equal distribution between negative and positive pressure.
B) 2/3 due to negative pressure, 1/3 due to positive pressure.
Up to what angle does the rudder flow remain laminar with a slim rudder, and up to what angle with a thick rudder?
A) Laminar up to 25° with a slim rudder and 15° with a thick rudder.
B) Laminar up to 15° with a slim rudder and 25° with a thick rudder.
C) Laminar up to 20° with a slim rudder and 30° with a thick rudder.
D) Laminar up to 30° with a slim rudder and 20° with a thick rudder.
B) Laminar up to 15° with a slim rudder and 25° with a thick rudder.
What is the primary function of Kort nozzles in relation to propeller thrust?
A) Reducing propeller thrust
B) Redirecting propeller thrust
C) Slowing down propeller thrust
D) Directing and accelerating propeller thrust
D) Directing and accelerating propeller thrust
When does the Kort nozzle effect have the most significant impact on propeller performance?
A) High propeller load at high speed
B) Low propeller load at low speed
C) High propeller load at low speed
D) Low propeller load at high speed
C) High propeller load at low speed
How do Kort nozzles compare to conventional propulsion in terms of prop walk in reverse, power requirement, and control?
A) Kort nozzles have more prop walk in reverse, higher power requirement, and worse control.
B) Kort nozzles have less prop walk in reverse, lower power requirement, and worse control.
C) Kort nozzles have less prop walk in reverse, lower power requirement, and better control.
D) Kort nozzles have more prop walk in reverse, higher power requirement, and better control.
C) Kort nozzles have less prop walk in reverse, lower power requirement, and better control.
For which range of speeds are Kort nozzles typically suitable?
A) Ships traveling at speeds greater than 12 knots
B) Ships traveling at speeds exactly 12 knots
C) Ships traveling at speeds less than or equal to 12 knots
D) Ships traveling at speeds less than 12 knots
C) Ships traveling at speeds less than or equal to 12 knots
What is the typical range of angles for Kort nozzles?
A) 15-20°
B) 25-30°
C) 35-40°
D) 40-45°
B) 25-30°
How much does a Kort nozzle typically increase thrust in towing and pushing conditions?
A) 5-10%
B) 10-15%
C) 15-25%
D) 25-30%
C) 15-25%
By what percentage do Kort nozzles typically increase thrust at zero speed?
A) 10%
B) 20%
C) 30%
D) 40%
C) 30%
What percentage of ahead thrust do modern Kort nozzles typically produce when backing?
A) 50%
B) 60%
C) 70%
D) 80%
C) 70%
What proportion of the blade surface does the Becker rudder flap typically occupy?
A) 1/8
B) 1/4
C) 1/2
D) 3/4
B) 1/4
What is the typical relationship between the angle of the Becker rudder flap and the angle of the rudder?
A) The same angle
B) Half the angle
C) Twice the angle
D) Three times the angle
C) Twice the angle
Under what condition may the Becker rudder flap exceed perpendicular to water flow?
A) Speed > 4 knots
B) Speed = 4 knots
C) Speed < 4 knots
D) Speed is irrelevant to this condition
C) Speed < 4 knots
What is the maximum angle that a Becker rudder may be angled?
A) 50°
B) 60°
C) 70°
D) 80°
C) 70°
By what percentage can a Becker rudder increase lift?
A) Up to 30%
B) Up to 45%
C) Up to 60%
D) Up to 75%
C) Up to 60%
How much of the ahead thrust can be created by the sideways thrust from a Becker rudder?
A) Up to 25%
B) Up to 35%
C) Up to 50%
D) Up to 65%
C) Up to 50%
At what speed does a Schilling rudder (fish tail rudder) typically create much greater forces than a conventional rudder?
A) Over 5 knots
B) Over 6 knots
C) Over 7 knots
D) Over 8 knots
C) Over 7 knots
Under what condition are high rudder angles on a Schilling rudder (fish tail rudder) typically practical?
A) At high speed
B) At medium speed
C) At low speed
D) At any speed
C) At low speed
By what percentage does a Schilling rudder typically have more lift compared to a conventional rudder?
A) 10-20%
B) 20-30%
C) 30-40%
D) 40-50%
C) 30-40%
At what angle does a Schilling rudder typically have maximum lift, and up to what angle can it be effectively used?
A) Maximum lift at 30% angle, can be used up to 60% angle
B) Maximum lift at 40% angle, can be used up to 70% angle
C) Maximum lift at 50% angle, can be used up to 80% angle
D) Maximum lift at 60% angle, can be used up to 90% angle
B) Maximum lift at 40% angle, can be used up to 70% angle
What feature does a rotor rudder have on its leading edge, and at what rudder angle does it typically begin turning?
A) It has a flap on its leading edge, and it begins turning at about 10° rudder angle.
B) It has a cylinder on its leading edge, and it begins turning at about 15° rudder angle.
C) It has a fin on its leading edge, and it begins turning at about 20° rudder angle.
D) It has a vortex generator on its leading edge, and it begins turning at about 25° rudder angle.
B) It has a cylinder on its leading edge, and it begins turning at about 15° rudder angle.
At what rudder angle does the cylinder on a rotor rudder typically reach maximum rotation?
A) 20°
B) 25°
C) 30°
D) 35°
B) 25°
Under what conditions does a rotor rudder typically stall?
A) At high speed and rudder angles up to 45°
B) At low speed and rudder angles up to 55°
C) At high speed and rudder angles up to 65°
D) It rarely stalls, even at low speed and rudder angles up to 65°
D) It rarely stalls, even at low speed and rudder angles up to 65°
How does the displacement-to-horsepower ratio typically vary among different types of ships?
A) 10x HP for container ships, 1.5x HP for VLCC, 1x HP for passenger ships
B) 10x HP for VLCC, 1.5x HP for container ships, 1x HP for passenger ships
C) 1x HP for VLCC, 1.5x HP for container ships, 10x HP for passenger ships
D) 1x HP for container ships, 1.5x HP for VLCC, 10x HP for passenger ships
B) 10x HP for VLCC, 1.5x HP for container ships, 1x HP for passenger ships
What is the typical propulsive force generated per unit of horsepower in forward motion, and what is the corresponding value for reverse motion?
A) 1 ton per 100 HP in forward motion, 0.6 ton per 100 HP in reverse motion
B) 0.6 ton per 100 HP in forward motion, 1 ton per 100 HP in reverse motion
C) 1 ton per 50 HP in forward motion, 0.6 ton per 50 HP in reverse motion
D) 0.6 ton per 50 HP in forward motion, 1 ton per 50 HP in reverse motion
A) 1 ton per 100 HP in forward motion, 0.6 ton per 100 HP in reverse motion
What is the typical range of transverse force relative to the propeller force?
A) 10-20%
B) 20-30%
C) 30-40%
D) 30-50%
D) 30-50%
What is the pivot point defined as in the context of ship motion?
A) The center of gravity of the ship
B) The point where the ship rotates around its longitudinal axis
C) The apparent center of the combined motions of drift and turn
D) The location where the ship’s propeller is situated
C) The apparent center of the combined motions of drift and turn
How does the pivot point location typically relate to the bow in a ship with a large block coefficient?
A) The pivot point is closer to the stern.
B) The pivot point is closer to the midship.
C) The pivot point is closer to the bow.
D) The pivot point is unaffected by the block coefficient.
C) The pivot point is closer to the bow.
What happens to the pivot point when a ship is trimmed by the stern?
A) It moves forward.
B) It remains stationary.
C) It moves aft.
D) It depends on other factors and may vary.
C) It moves aft.
What happens to the pivot point when a ship is trimmed by the bow?
A) It moves forward.
B) It remains stationary.
C) It moves aft.
D) It depends on other factors and may vary.
A) It moves forward.
How is the pivot point typically positioned relative to the center of forces (Fc) from the center of gravity (G)?
A) They are aligned.
B) They are perpendicular to each other.
C) They are always in the same direction.
D) They are always opposite to each other.
D) They are always opposite to each other.
How does the distance between the center of forces (Fc) and the center of gravity (G) affect the position of the pivot point (P)?
A) The further Fc is from G, the further P is from G.
B) The closer Fc is to G, the closer P is to G.
C) The further Fc is from G, the closer P is to Fc.
D) The closer Fc is to G, the further P is from Fc.
B) The closer Fc is to G, the closer P is to G.
What happens to the pivot point concerning the center of gravity (G) when a ship is turning due to lateral forces?
A) The pivot point moves away from G.
B) The pivot point remains stationary relative to G.
C) The pivot point moves closer to G.
D) The pivot point depends on other factors and may vary.
C) The pivot point moves closer to G.
How does the position of the pivot point under sternway with engines stopped compare to under sternway with engines operating astern?
A) The pivot point is further forward with engines stopped.
B) The pivot point is further aft with engines stopped.
C) The pivot point is closer to amidships with engines stopped.
D) The pivot point is unaffected by engine operation in this scenario.
B) The pivot point is further aft with engines stopped.
In a turning vessel with a 35° helm angle, what is the amount of drift observed?
A) 5°
B) 10°
C) 15°
D) 20°
B) 10°
How does trimming a ship by the head affect its lateral resistance and the time it takes to start or check a swing?
A) Lateral resistance is decreased, and the ship will take longer to start a swing and check a swing.
B) Lateral resistance is increased, and the ship will take longer to start a swing and check a swing.
C) Lateral resistance is decreased, and the ship will take less time to start a swing and check a swing.
D) Lateral resistance is increased, and the ship will take less time to start a swing and check a swing.
A) Lateral resistance is decreased, and the ship will take longer to start a swing and check a swing.
How does trimming a ship by the head affect its turning ability and the potential risk regarding acceleration?
A) Trimming by the head decreases turning ability and poses no risk regarding acceleration.
B) Trimming by the head increases turning ability but poses a risk of acceleration exceeding the rudder’s turning capacity.
C) Trimming by the head increases turning ability and poses no risk regarding acceleration.
D) Trimming by the head decreases turning ability but poses a risk of acceleration exceeding the rudder’s turning capacity.
B) Trimming by the head increases turning ability but poses a risk of acceleration exceeding the rudder’s turning capacity.
How does trimming a ship by the head affect the propeller submergence and rudder thrust?
A) Trimming by the head increases propeller submergence and rudder thrust.
B) Trimming by the head decreases propeller submergence and rudder thrust.
C) Trimming by the head has no effect on propeller submergence but decreases rudder thrust.
D) Trimming by the head has no effect on propeller submergence but increases rudder thrust.
B) Trimming by the head decreases propeller submergence and rudder thrust.
How does trimming a ship by the head and being under sternway affect its lateral resistance?
A) It increases lateral resistance.
B) It decreases lateral resistance.
C) It has no effect on lateral resistance.
D) It depends on other factors and may vary.
B) It decreases lateral resistance.
How does trimming a ship by the head affect the size of its turning circle compared to when it is on an even keel?
A) Trimming by the head results in a larger turning circle.
B) Trimming by the head results in a smaller turning circle.
C) Trimming by the head has no effect on the turning circle.
D) It depends on other factors and may vary.
B) Trimming by the head results in a smaller turning circle.
How does trimming a ship by the head affect the phenomenon of bow squat?
A) It reduces bow squat due to increased pressure under the bow.
B) It has no effect on bow squat.
C) It exacerbates bow squat due to low pressure developing under the bow.
D) It increases bow squat due to increased pressure developing under the bow.
C) It exacerbates bow squat due to low pressure developing under the bow.
How does trimming a ship by the stern affect its lateral resistance when moving ahead or sideways?
A) It increases lateral resistance.
B) It decreases lateral resistance.
C) It has no effect on lateral resistance.
D) It depends on other factors and may vary.
B) It decreases lateral resistance.
How does trimming a ship by the stern affect the size of its turning circle?
A) Trimming by the stern results in a smaller turning circle due to less lateral resistance.
B) Trimming by the stern results in a larger turning circle due to less lateral resistance.
C) Trimming by the stern has no effect on the size of the turning circle.
D) It depends on other factors and may vary.
B) Trimming by the stern results in a larger turning circle due to less lateral resistance.
How does trimming a ship by the stern affect the torque experienced when backing?
A) Trimming by the stern increases torque when backing.
B) Trimming by the stern decreases torque when backing.
C) Trimming by the stern has no effect on torque when backing.
D) It depends on other factors and may vary.
B) Trimming by the stern decreases torque when backing.
What happens to transverse thrust and the position of the pivot point when a ship is making headway with engines astern?
A) Transverse thrust decreases, and the pivot point moves forward.
B) Transverse thrust increases, and the pivot point moves forward.
C) Transverse thrust decreases, and the pivot point moves aft.
D) Transverse thrust increases, and the pivot point moves aft.
D) Transverse thrust increases, and the pivot point moves aft.
When is transverse thrust at its maximum during ship operations, and how does it change as the ship transitions from making headway to making sternway?
A) Transverse thrust is maximum when the ship is making headway, and it decreases as the ship begins to make sternway.
B) Transverse thrust is maximum when the ship is making sternway, and it decreases as the ship begins to make headway.
C) Transverse thrust is maximum when the ship is making very slow headway, and it decreases as the ship begins to make sternway and the pivot point moves near the stern.
D) Transverse thrust is maximum when the ship is making very slow headway, and it decreases as the ship begins to make sternway and the pivot point moves near the bow.
C) Transverse thrust is maximum when the ship is making very slow headway, and it decreases as the ship begins to make sternway and the pivot point moves near the stern.
What percentage of the ahead power typically contributes to transverse thrust from kicks ahead?
A) 25%
B) 35%
C) 45%
D) 55%
C) 45%
What percentage of the astern power typically contributes to transverse thrust from kicks astern, both initially and after sternway is gathered?
A) 5% initially, 10% after sternway is gathered
B) 10% initially, 5% after sternway is gathered
C) 10% initially, 15% after sternway is gathered
D) 15% initially, 10% after sternway is gathered
B) 10% initially, 5% after sternway is gathered
What percentage of the astern power typically contributes to transverse thrust from continuous operation astern?
A) 5%
B) 10%
C) 15%
D) 20%
C) 15%
Why is transverse thrust not effective at high speed?
A) Because propeller wash does not reach the hull.
B) Because the propeller is not rotating fast enough.
C) Because the ship is too heavy.
D) Because the rudder is not fully engaged.
A) Because propeller wash does not reach the hull.
At what speed is transverse thrust typically not effective for turning?
A) Over two knots
B) Over three knots
C) Over four knots
D) Over five knots
C) Over four knots
What are the consequences of using transverse thrust at speed for turning?
A) An increase in the rate of turn and a narrower turning circle.
B) A decrease in the rate of turn and a wider turning circle.
C) No effect on the rate of turn but a narrower turning circle.
D) No effect on the rate of turn but a wider turning circle.
B) A decrease in the rate of turn and a wider turning circle.
How should a narrow-beamed ship with propellers close together be operated due to low torque?
A) As a single-screw ship
B) As a twin-screw ship
C) As an outboard-driven ship
D) As a trimaran
A) As a single-screw ship
Under what condition might a ship with two propellers and one rudder steer better?
A) With engines at full power
B) With engines stopped
C) With one engine running
D) With both engines running at half power
B) With engines stopped
How should a ship with inboard turning fixed pitch propellers be operated due to transverse torque opposing thrust when one engine is ahead and one is astern?
A) As a twin-screw ship
B) As a single-screw ship
C) As an outboard-driven ship
D) As a trimaran
B) As a single-screw ship
What is the eccentricity effect related to propellers?
A) It is the increase in propeller efficiency at high speeds.
B) It is the vibration caused by propeller imbalance.
C) It is the torque created by a propeller being off centerline.
D) It is the reduction in propeller noise in shallow waters.
C) It is the torque created by a propeller being off centerline.
Why are twin fixed-pitch propellers commonly set to outboard turning configuration?
A) To reduce propeller efficiency
B) To increase wake turbulence
C) To decrease twisting ability
D) To achieve a smaller, broader wake and increased twisting ability
D) To achieve a smaller, broader wake and increased twisting ability
Why are inward turning variable pitch propellers (VPP) considered best for maneuvering?
A) Because they reduce the deadwood effect
B) Because they increase wake turbulence
C) Because they increase twisting ability
D) Because the deadwood effect is increased when water is directed inboard against the hull
D) Because the deadwood effect is increased when water is directed inboard against the hull
What are the combined effects in a twin-screw configuration with fixed-pitch propellers, outboard turning, and twist?
A) Torque effects and eccentricity effects add, deadwood effect cancels out
B) Torque effects and eccentricity effects cancel out, deadwood effect adds
C) Torque effects and eccentricity effects add, deadwood effect adds
D) Torque effects and eccentricity effects cancel out, deadwood effect cancels out
C) Torque effects and eccentricity effects add, deadwood effect adds
What happens in a twin-screw configuration with fixed-pitch propellers, inboard turning, and twist?
A) Torque effect of both shafts opposes and diminishes eccentricity effect, deadwood effect is increased.
B) Torque effect of both shafts opposes and diminishes eccentricity effect, deadwood effect is decreased.
C) Torque effect of both shafts adds and increases eccentricity effect, deadwood effect is increased.
D) Torque effect of both shafts adds and increases eccentricity effect, deadwood effect is decreased.
B) Torque effect of both shafts opposes and diminishes eccentricity effect, deadwood effect is decreased.
What occurs in a twin-screw setup with variable pitch propellers (VPP), outboard turning, and twist?
A) Torque effects cancel each other out, and only the eccentricity effect contributes to twist, deadwood effect is increased because the current is directed outboard.
B) Torque effects cancel each other out, and only the eccentricity effect contributes to twist, deadwood effect is decreased because the current is directed outboard.
C) Torque effects add together, and only the eccentricity effect contributes to twist, deadwood effect is increased because the current is directed outboard.
D) Torque effects add together, and only the eccentricity effect contributes to twist, deadwood effect is decreased because the current is directed outboard.
B) Torque effects cancel each other out, and only the eccentricity effect contributes to twist, deadwood effect is decreased because the current is directed outboard.
What happens in a twin-screw setup with variable pitch propellers (VPP), inboard turning, and twist?
A) Torque effects cancel each other out, and only the eccentricity effect contributes to twist, deadwood effect adds because wash is directed against the hull.
B) Torque effects add together, and only the eccentricity effect contributes to twist, deadwood effect adds because wash is directed against the hull.
C) Torque effects cancel each other out, and only the eccentricity effect contributes to twist, deadwood effect diminishes because wash is directed against the hull.
D) Torque effects add together, and only the eccentricity effect contributes to twist, deadwood effect diminishes because wash is directed against the hull.
A) Torque effects cancel each other out, and only the eccentricity effect contributes to twist, deadwood effect adds because wash is directed against the hull.
In a twin-screw setup with fixed inboard propellers, how does the torque affect the eccentricity?
A) Torque diminishes eccentricity.
B) Torque increases eccentricity.
C) Torque cancels out eccentricity.
D) Torque has no effect on eccentricity.
A) Torque diminishes eccentricity.
In a setup with variable outboard propellers, what occurs with the torque?
A) Torque cancels torque.
B) Torque increases torque.
C) Torque diminishes torque.
D) Torque has no effect on torque.
A) Torque cancels torque.
What is the characteristic of the wake produced by a ship, in terms of wave directions?
A) It produces waves only at 19° to the longitudinal axis.
B) It produces waves only at 54° to the longitudinal axis.
C) It produces two sets of waves, one at 19° and the other at 54° to the longitudinal axis.
D) It produces waves at various angles to the longitudinal axis, depending on the ship’s speed and hull design.
C) It produces two sets of waves, one at 19° and the other at 54° to the longitudinal axis.
How does frictional resistance typically change over time if a ship’s hull is not cleaned?
A) It decreases by 15% each year.
B) It increases by 15% each year.
C) It remains constant over time.
D) It varies depending on other factors.
B) It increases by 15% each year.
How does an increase in hull roughness of 0.1mm typically affect hull resistance?
A) It causes a 5% increase in hull resistance.
B) It causes an 8% increase in hull resistance.
C) It causes an 11% increase in hull resistance.
D) It causes a 15% increase in hull resistance.
C) It causes an 11% increase in hull resistance.