Shiphandling Flashcards

1
Q

When turning in shallow water diameter of the turn will ? By how much?

A

<p>Increase. By twice the diameter.</p>

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2
Q

What happens to rate of turn in shallow water verses deep water?

A

<p>Remains constant, though turning circle (tactical) diameter increases in shallow water.</p>

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3
Q

Is transverse thrust while moving ahead more noticeable on a small or large ship

A

<p>Small, until almost no effect on ULCC and VLCC sized ships.</p>

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4
Q

If accelerating will turning circle diameter be larger or smaller than at constant RPMs.

A

Smaller. (Rule of thumb: Starting DIW with turns for 6 kts, turning circle will be 1/2 size of circle starting at 6 kts with constant RPM)

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5
Q

At what speed through the water does a bow thruster become effective?

A

Two knots.

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6
Q

At what depth do shallow water effects take place?

A

Depth of 1.2 to 1.4 of draft

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7
Q

In shallow water does ship become more directionally stable? Steering improves?

A

Yes

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8
Q

Does turning circle diameter increase or decrease with shallow water effects?

A

Increase

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9
Q

Does the ship twist more or less when backed in shallow water?

A

More

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10
Q

Does a ship carry further or shorter in shallow water?

A

Further

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11
Q

What direction from the wind does the bow tend when backing?

A

Bow falls away and ship will back into the wind. Due to pivot point moving aft.

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12
Q

As a ship reduces speed it will tend to turn in what direction relative to the wind?

A

It will turn into the wind.

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13
Q

What creates the pivot point?

A

The couple between the forward momentum of the vessel and the longitudinal resistance created by the water.

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14
Q

Where is the pivot point when the vessel is at a constant speed?

A

Approximately 1/4 of the ships length from the bow.

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15
Q

How does the pivot point location effect turning levers?

A

The moment of force times the length to the pivot point creates the turning lever.

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16
Q

How does the excessive use of astern bells effectively put a ship ‘out of control’?

A

Leaves the ship exposed to transverse thrust, wind, tide, and bank or shallow water effect.

17
Q

How can loss of rudder control be overcome at slow speeds?

A

By using the ‘Kick Ahead’ or ‘Pumping the Rudder’ technique.

18
Q

When using the ‘Kick Ahead’ or ‘Pumping the Rudder’ technique what is important to keep in mind about rudder position?

A

Insure rudder is hard over to prevent unwanted increases in ahead motion.

19
Q

Which is more effective for ‘pumping the rudder’ or a ‘kick ahead’? A steam ship or a diesel ship?

A

A diesel ship because it comes up to speed faster.

20
Q

What safety should be used with a turbine plant?

A

Leave dead slow ahead as long as possible because plant can be slow to come on line.

21
Q

What creates transverse thrust?

A
  1. Helical discharge on the port side of the rudder. 2. Upward flow from the hull puts more pressure on the downward sweeping blades.
22
Q

What direction does a right hand prop move the bow when rotating ahead?

A

Port

23
Q

What direction does a left and prop move the bow when turning ahead?

A

starboard

24
Q

What direction does a right hand prop move the stern when turning astern?

A

Port

25
Q

What direction does a left hand prop move the stern when turning astern?

A

Starboard

26
Q

When turning ahead what direction does a right hand prop turn when viewed from astern?

A

Clockwise

27
Q

When turning ahead what direction does a left handed propeller turn when viewed from astern?

A

Counter clockwise

28
Q

What percentage of applied power will be transverse thrust?

A

5-10%

29
Q

What is the wedge effect?

A

The movement of water, from astern wheel wash, down between the ship and a solid face acting as a cushion.

30
Q

In what direction is does the transverse thrust of a left handed controllable pitch propeller move the stern when backing?

A

To port like a right handed fixed propeller.

31
Q

Does transverse thrust increase or decrease when shrouded by a nozzle?

A

Decrease

32
Q

Where is the pivot point when dead in the water.

A

At center of underwater mass, approximately amidships depending on trim.

33
Q

Where is pivot point when initially moving ahead?

A

1/8 the ship length from the bow.

34
Q

Where is pivot point while turning when moving ahead at a constant speed?

A

1/3 of ships length from the bow.

35
Q

What is the type resistance which develops a ship to moving bodily sideways through the water?

A

Lateral Resistance

36
Q

Why are turning circles at different speeds approximately the same diameter?

A
  1. Because lateral resistance and rudder force find a balance. 2. Only the rate of turn changes 3. Speed entering a turn does not increase the turning ability.
37
Q

How much of a speed reduction can be expected in a turn with constant RPMs? Why?

A

30-50% loss, due to the increase of lateral resistance due to the increase of exposed side shell.

38
Q

At what RPM is the minimum radius achieved in a standing turn?

A

Dead in the water to dead slow ahead

39
Q

What are the three different directional stability conditions?

A
  1. Stable - Steadies up when rudder is put amidships 2. Neutral - Continues a swing at a steady rate with rudder amidships 3. Negative - Swings at increasing rate with rudder amidships