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Local Pilotage 2 > 7. Behavior and Handling of Ships 100% > Flashcards

7. Behavior and Handling of Ships 100% Flashcards

1
Q

What is the scale size of manned model ships?

A

25:1

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2
Q

On manned models ship’s speed is _____ times faster.

A

five

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3
Q

About what point does rotational motion occur?

A

The pivot point

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4
Q

Does the movement of the pivot point change the lever arm for rotational force?

A

As the distance between the applied force and the pivot point increases, the lever arm increases and decreases. The correct answer is: Yes

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5
Q

Define momentum:

A

The quantity of motion measured by the product of mass and velocity.

M = m’ x v

also

F = m’ x v

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6
Q

Displacement varies with the ______ of the ship’s dimensions.

  1. Square
  2. Cube
  3. Fourth Power
A

Hooyer p. 9 The correct answer is: Number 2 Cube

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7
Q

Wetted area varies with the _______ of the ship’s demesions. 1. Square 2. Cube 3. Fourth Power

A

Hooyer p. 9 The correct answer is: Number 1 Square

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8
Q

What is the best method to control momentum?

A

Keep speed down

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9
Q

At low speed _____________ is responisble for most of the underwater resistance met by the vessel.

A

frictional resistance Hooyer p. 10

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10
Q

At higher speeds _________ absorbs the ship’s energy

A

wave making system Hooyer p. 10

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11
Q

Both longitudinal and lateral resistance act as forces and play a role in determining the position of the ___________.

A

pivot point Hooyer p. 11

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12
Q

Along with the magnitude of a force the ________ of a force is important.

A

leverage Hooyer p. 11

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13
Q

What are the four motions?

A

Longitudinal, Rotational, Lateral, Relative Hooyer p. 11

RoReLoLa

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14
Q

After a ship comes out of current the ___________ motion manifests itself as momentum.

A

relative

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15
Q

It is easier to stop _________. 1. rotational motion 2. lateral motion

A

Hooyer p. 12 The correct answer is: Number 2 lateral motion

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16
Q

Doppler logs may show speed _______

  1. through the water
  2. over the ground
  3. Both
A

Hooyer p. 13 The correct answer is: both

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17
Q

__________ is used with the foreship doppler to determine stern motion

A

Rate of turn indicator

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18
Q

Doppler logs become unreliable under ______ knots.

  1. one
  2. two
  3. three
  4. four
A

Hooyer p. 13 The correct answer is: Number 1 one

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19
Q

Angle of approach can be assessed with the _________.

A

compass repeater on the bridge wing. Hooyer p. 14

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20
Q

When navigating in a current, the speed of a head current is the difference between the doppler indicated _____ and _____.

A

STW and SOG

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21
Q

In general terms 100hp is equal to _____ ton(s) bollard pull

  1. 0.5
  2. 1
  3. 1.5
  4. 2
A

Hooyer p. 15 The correct answer is: Number 2 1

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22
Q

Longitudinal resistance is equal to _______ of propulsion force under constant speed.

  1. 25%
  2. 30%
  3. 35%
  4. 40%
A

Hooyer p. 15 The correct answer is: Number 1 25%

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23
Q

Transverse force of propeller when working astern is equal to ________ of applied power.

  1. 1-2%
  2. 2-5%
  3. 5-10%
  4. 7-15%
A

Hooyer p. 15 The correct answer is: Number 3 5-10%

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24
Q

The motion of a ship can be seen as a combination of _________, __________, and __________ motions

  1. Longitudinal
  2. Lateral
  3. Rotational
  4. Relative
A

Hooyer p. 16 The correct answer is:

longitudinal, lateral, and Rotational

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25
Q

Is the location of the pivot point constant?

A

Hooyer p. 16 The correct answer is: No

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26
Q

Does frictional drag have an effect on the location of the pivot point?

A

Hooyer p. 17 The correct answer is: No

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27
Q

What dictates the location of the pivot point?

A

The opposition between the center of gravity and longitudinal resitance Hooyer p. 17

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28
Q

In what trim condition is the pivot point most likely to be in the center of the vessel?

A

When on an even keel. Hooyer p. 17

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29
Q

What is the drift angle?

A

The angular difference between the heading and course over ground.

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30
Q

When a vessel is turning what happens to the location of the pivot point relative to its location on a steady heading?

A

It moves towards midships Hooyer p.17

When Making Headway it shifts aft.

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31
Q

What limits drift angle in a turn

A

The lateral resistance of the exposed side shell Hooyer p. 18

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32
Q

If two tugs of equal power are working at even distance from midships on a ship that is DIW what type of motion will occur? 1. Lateral 2. Rotational

A

Hooyer p. 18 The correct answer is: Number 1 Lateral

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33
Q

What can be deduced from rotation of the ship when two tugs are pushing with equal power at equal distance from midships.

A

The ship has longitudinal motion and therefor the pivot point has moved Hooyer p. 19

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34
Q

When a motor ship is stopped what is overcome first when using hard over rudder? 1. Longitudinal inertia 2. Lateral inertia

A

Hooyer p. 21 The correct answer is: Number 2 Lateral inertia

35
Q

What is the location of the pivot point on a vessel starting from dead in the water ________ lenght from bow? (L/B ratio of 8)

  1. 1/16
  2. 1/8
  3. 1/4
  4. 1/3
A

Hooyer p. 21 The correct answer is:

Number 2 1/8

36
Q

Does the pivot point move when the ship is turning at a constant speed?

A

Hooyer p. 22 The correct answer is: No

37
Q

What is the location of the pivot point when the ship is at constant speed on a steady heading?

  1. 1/16
  2. 1/8
  3. 1/4
  4. 1/3
A

Hooyer p. 22 The correct answer is:

Number 3 1/4

38
Q

As beam decreases the pivot point moves further _______. 1. forward 2. aft

A

Hooyer p. 22 The correct answer is: Number 1 forward

39
Q

While speed is increasing the pivot point moves further ________.

  1. forward
  2. aft
A

Hooyer p. 23 The correct answer is: Number 1 forward

40
Q

While speed is decreasing the pivot point moves further ________. 1. forward 2. aft

A

Hooyer p. 23 The correct answer is: Number 2 aft

41
Q

What is easier to overcome from DIW? 1. Longitudinal inertia 2. Rotational inertia

A

Hooyer p. 23 The correct answer is: Number 2 Rotational inertia

42
Q

_________ helps to make a tight swing from DIW?

  1. Lateral inertia
  2. Longitudinal inertia
  3. Rotational inertia
A

The correct answer is: Number 2 Longitudinal inertia

43
Q

Does a turbine powered ship or a motor ship turn sharper from DIW?

  1. Motor ship
  2. Turbine ship
A

Because the tubine comes up to speed slower and thereby has longer to overcome longitudinal inertia. Hooyer p. 23 The correct answer is: Number 1 Motor ship

44
Q

With headway on what causes transverse thrust?

A

The thrust of the upper blades against the rudder If the propeller is not fully submerged the lower blades having more ‘bite’ Hooyer p. 24

45
Q

When is transverse thrust maximum when moving ahead?

A

When starting from DIW, as the lever arm is longest. Hooyer p. 24

46
Q

Does a relatively large propeller for the size of ship make turning circles in opposite direcctions _______. 1. the same size 2. different sizes

A

Due to increased transverse thrust. Hooyer p. 25 The correct answer is: Number 2 different sizes

47
Q

Do low speed large diameter propellers create more or less transverse thrust? 1. more 2. less

A

Hooyer p. 25 The correct answer is: Number 1 more

48
Q

Does a duct or nozzle around a propeller create more or less transverse thrust. 1. more 2. less

A

because it prevents the water from reaching the stern at such a steep angle Hooyer p. 25 The correct answer is: Number 2 less

49
Q

When is the effect of transverse thrust the greatest? 1. Pivot point aft 2. Pivot point forward

A

Hooyer p. 25 The correct answer is: Number 2 Pivot point forward

50
Q

How does the pivot point move when a ship is trimmed by the head?

  1. further forward
  2. further aft
A

The correct answer is: Number 2 further aft

51
Q

What happens to the pivot point when moving astern with stern propulsion versus moving astern without?

  1. it remains constant
  2. it moves fwd
  3. it moves aft
A

Hooyer p. 26 The correct answer is: Number 2 it moves further forward from the stern

52
Q

Does the use of a bow thruster or bow tug move the pivot point further forward or aft with stern way?

  1. further aft
  2. further forward
A

and thereby decreases the lever arm of transverse thrust Hooyer p. 26 The correct answer is: Number 1 further aft

53
Q

If the transverse force of the rudder is used as a lever to ‘lift’ the center of gravity the ________ would be the fulcrum.

A

Pivot Point Hooyer p. 27

54
Q

The _________ is instrumental in proportioning lateral resistance

A

Pivot Point

As the pivot point moves farther forward the lateral resistance increases due to more side shell being forced uphill. As it moves further back the lateral resistance decreases

55
Q

What has more lateral resistance?

  1. A beamy ship
  2. A narrow ship
A

Being that the pivot point is further forward in a narrow ship there is relatively more area aft of the pivot point. Hooyer p. 28

The correct answer is: Number 2 A narrow ship

56
Q

All other things being equal which ship has a tighter turning circle?

  1. A beamy ship
  2. A narrow ship
A

Because the pivot point is further aft on the beamy ship their is less lateral resistance aft of the pivot point. Hooyer p. 28

The correct answer is: Number 1 A beamy ship

Narrow ships have more lateral resistance so they have a larger turning circle

57
Q

All other things being equal which ship will have a larger drift angle?

  1. A beamy ship
  2. A narrow ship
A

Beacuse the pivot point is further aft on a beamy ship there is less lateral resistance aft of the pivot point and thereby the ship turns sharper, eg. a larger drift angle and smaller turning circle. Hooyer p. 28

The correct answer is: Number 1 A beamy ship

58
Q

When turning a vessel if counter rudder is used to slow or reverse the turn, what will allow the turn to recommence if the rudder is eased to quickly.

A

Rotational momentum The rudder should be eased slowly so that the forces that are countering the turn may remain balanced. Hooyer p. 29

59
Q

Which way does the pivot point move when accelerating?

  1. Forward
  2. Remains Stationary
  3. Aft
A

Hooyer p. 30 The correct answer is: Number 1 Forward

The greater the headway, the further forward the pivot point moves.

60
Q

What is the advantage of using hard rudder with increased engine RPMs?

A

The turning lever increases because the piovt point moves forward and the increase of thrust over the rudder creating more lift. This will continue until the change in longitudinal forces balance out. Hooyer p. 30

61
Q

Why will a turning ship not make the posted corresponding speed for the current RPMs?

A

The increased lateral resistance developed when turning. Hooyer P. 30

62
Q

Which way does the pivot point move when decelerating?

  1. Forward
  2. Remains Stationary
  3. Aft
A

Hooyer p. 30 The correct answer is: Number 3 Aft

63
Q

What forces the pivot point further aft when turning? Where does it end up?

  1. 1/8 LWL
  2. 1/4 LWL
  3. 1/3 LWL
  4. 1/2 LWL
A

The increase in transverse force on the foreship. Hooyer p. 31

The correct answer is: Number 3 1/3 LWL

The vessel begins to slowdown and the pivot point moves aft.

64
Q

In which direction does the pivot point move when a vessel is trimmed by the head?

  1. Forward
  2. Remains stationary
  3. Aft
A

Therefore the drift angle will increase and the turning circle will be smaller

The correct answer is: Number 3 Aft

65
Q

If a ship is down by the _______ it is more difficult to steer. 1. Head 2. Stern

A

The turning lever is shorter because the pivot point moves aft and the rudder is less submerged. Hooyer p. 31 The correct answer is: Number 1 Head

66
Q

Why does a ship trimed by the stern have a larger turning circle?

A

The lateral resistance is greater due to the pivot point being further forward. This decreases the drift angle. Hooyer p. 31

As drift angle decreases the pivot point moves fwd.

67
Q

Why does a ship trimmed by the stern steer better? (2 reasons)

A
  1. Increased leverage of rudder force with pivot point further forward
  2. Propeller is more submerged Hooyer p. 31
68
Q

What makes rudder cycling effective in slowing a ship?

A

The increase in lateral resistance exposed while the ship is veering. Hooyer p. 32

69
Q

What is initially more effective to slow a ship from full ahead?

  1. Dead slow ahead
  2. Stop engines
A

Hooyer P. 33 The correct answer is: Number 1 Dead slow ahead

70
Q

What is initially more effective at slowing a ship from full ahead?

  1. Dead slow astern
  2. Full astern
A

Because at full astern most of the force is lost to cavitation. Hooyer p. 33 The correct answer is:

Number 1 Dead slow astern

71
Q

________ enables a ship to make a short turn from DIW.

A

Inertia Resists longitudinal acceleration from occuring. Hooyer p. 33

72
Q

How many ship’s lengths is the theoretical turning circle of a ship with a L/B ratio of 9?

A

Hooyer p. 34 You could have answered with any of the following:

  1. 4
  2. four
73
Q

How many ship’s lengths is the thoretical turning circle of a ship with a L/B ratio of 5?

A

Hooyer p. 34 You could have answered with any of the following:

  1. 3
  2. three
74
Q

Which has a slightly larger turning circle. 1. higher constant speed 2. lower constant speed

A

Because of the greater momentum and longer steering lever contribute to less drift angle. Hoooyer p. 34 The correct answer is: Number 1 higher constant speed

75
Q

Which has a larger turning circle? 1. in ballast 2. in product

A

Smaller rudder area ratio, and possibly less UKC Hooyer p. 34 The correct answer is: Number 2 in product

76
Q

Why is a turning circle larger in shallow water?

A

Increased lateral resistance. Water is not able to move under the hull, which increases the lateral resistance and decreases the drift angle. Hooyer P. 35

77
Q

Which results in a quicker turn when moving ahead? 1. Turning into the wind 2. Turning away from the wind

A

Hooyer p. 35 The correct answer is: Number 1 Turning into the wind

78
Q

When operating the engines astern but still making headway transverse thrust can be concidered to be _____ % of applied power

A

Hooyer p. 36 You could have answered with any of the following: 1. 5 2. five

79
Q

When operating the engines astern with sternway transverse thrust can be concidered to be _____ % of applied power

A

Hooyer p. 36 You could have answered with any of the following: 1. 10 2. ten

80
Q

What can be done to prevent the effect of transverse thrust?

A

Giving a kick ahead to port to to get the stern swinging to starboard prior to backing down. Hooyer p. 36

81
Q

How can transverse thrust be accentuated?

A

Giving a kick to starboard to get the stern swining to port prior to backing down, so that rotational motion is already started. Hooyer p. 36

82
Q

On which is transverse thrust stronger? 1. Large ships with slow turning props 2. Small ships with fast turning props

A

Hooyer p. 37 The correct answer is: Number 1 Large ships with slow turning props

83
Q

What happens to water flow when backing down using full rudder?

A

It will partially block the propeller and make it less efficent.

Local Pilotage 2 (15 decks)

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