Test 1 Flashcards

1
Q

Length to beam ratio

A

L/B

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2
Q

Which ship turns more easily?

A

Wider beam

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3
Q

Block coefficient (coefficient of fineness) is equal to the

A

Ratio of the hull volume/ the cuboid containing it

V/ lxbxte

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4
Q

The higher the block coefficient

A

The harder it is to maneuver the ship

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5
Q

Bernoulli’s principle

A

Higher speed = lower pressure

Lower speed = higher pressure

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6
Q

Lift contributes to ?% of the propulsive action of the prop?

A

30-50%

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7
Q

A narrow ship easily maintains

A

It’s heading

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8
Q

Block coefficient can vary from

A

0.5 for a fast naval ship to about 0.85 for a VLCC

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9
Q

A propeller creates a propulsive force of about

A

One ton per 100 hp

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10
Q

The first successful steamship driven by screw propulsion to operate on the oceans was the

A

SS Archimedes

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11
Q

How does Bernoulli’s principle affect the operation of a propeller?

A

Lift is generated on the low pressure side of the blades

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12
Q

What is newtons third law?

A

Every action has an equal and opposite reaction

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13
Q

Newtons first

A

Object at rest will remain at rest unless acted on by an unbalanced force

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14
Q

Newtons second

A

Acceleration is produced when a force acts on a mass

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15
Q

What causes the Stern to move to port and provide hull wash on the starboard side when the engines are astern?

A

Deadwood effect

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16
Q

The greater the blade area ratio

A

The less vibration and noise

17
Q

Grader blade area ratio affects

A

Drag and reduces efficiency

18
Q

Where is cavitation most likely to appear?

A

The blade tips and leading edge

19
Q

Is aeration the same as cavitation?

A

No

20
Q

Are controllable pitch and variable pitch propellers the same?

A

Yes

21
Q

Two equal ships except one has a fixed pitch and the other has a controllable pitch. They’re traveling in a straight line and they both stopped or propulsion. Which will respond better?

A

The ship with a fixed pitch propeller because it is still allowing water over the rudder and the controllable does not

22
Q

A broad ship will stop turning when the rudder is returned to midship

A

False

23
Q

Which ship has a wider turning diameter, a broad beam or a narrow beam?

A

Narrow beam

24
Q

Are controllable pitch propellers more efficient than fixed pitch propellers going to Stern?

A

No

25
Q

The ratio of the rudder blade to the underwater area of the hull varies from

A

1.5-5%

26
Q

A rudder is limited to a range of about what angle?

A

35

Because the rudder can stall

27
Q

Which rudder has two pieces coming off the stem posts that are separate from each other?

A

Balanced

28
Q

The first element in design of a rudder is the

A

Surface area

29
Q

What are the two types of high-performance rudders in the modern merchant marine fleet?

A
Becker rudder (flap rudder)
Schilling rudder
30
Q

What’s the main disadvantage of a Kort nozzle

A

In speeds greater than 12 kn drag is significantly increased

31
Q

What kind of rudder loses effectiveness at angles greater than 10°?

A

Balanced spade

32
Q

The old type of rudder mounted with the prop

A

Contra guide

33
Q

What is the penalty for a large rudder?

A

Drag

34
Q

Why is a thruster propeller not the same design as a main propulsion propeller?

A

Because it only applies transversed thrust to port or starboard