Final Flashcards

1
Q

6 degrees of freedom

A
Roll
Pitch
Surge
Sway
Heave
Yaw
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2
Q

The ratio of length to beam

A

Effects turning quality

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3
Q

A wider vessel

A

Turns better

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4
Q

A narrow vessel

A

Maintains heading

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5
Q

A broad ship requires

A

More work to maintain its heading

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6
Q

What criteria characterize a ship?

A
The hull 
Propulsión type
Rudder type
Special equipment: thrusters
Windward surface
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7
Q

The ratio of the hull volume over the cuboid containing it is called the

A

Block coefficient

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8
Q

Block coefficient formula

A

V / L x B x Te

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9
Q

Block coefficient can vary from

A

.5 fast naval to .85 for VLCC

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10
Q

Propeller creates a force of about

A

1 ton per 100 hp

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11
Q

Most common engine

A

Slow speed diesel

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12
Q

First successful steamship screw propulsion on oceans

A

SS Archimedes

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13
Q

HMS Rattler

A

Screw powered wins tug of war with paddle wheel HMS Alecto at Dover trails 1845

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14
Q

High pressure creates

A

Thrust

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15
Q

Low pressure creates

A

Drift

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16
Q

Bernoulli

A

High speed = low pressure

Low speed = high pressure

17
Q

More blades =

A

Less noise

18
Q

Characteristics a propeller

A

Diameter
Number and type of blades
Pitch

19
Q

Highly skewed propellers have very

A

Strongly formed blades and reduces vibrations

20
Q

Low skewed propellers

A

Generate choppy frequency at uppermost point and causes significant vibration

21
Q

Is cavitation and aeration the same

A

Nope

22
Q

Are controllable and variable pitch the same?

A

Yes

23
Q

Cavitation generates

A

Pressure variations and causes erosion and increases drag and vibration

24
Q

Deadwood effect

A

Causes stern to kick out

25
Q

Advantages of controllable pitch

A

Change of speed reliably obtained without risk of starter issues
Engine is more efficient
No limit to number of reverse and forward bells
Of blade damage, only the one blade needs replaced

26
Q

Disadvantages of controllable pitch

A

Complex
Less efficient in reverse
Line fouling

27
Q

2 high performance rudders

A

Becker

Schilling

28
Q

Kort nozzle major disadvantage

A

Drag significantly increases with speeds greater than 12 kts

29
Q

Semi balanced rudder

A

Mariner rudder

30
Q

Criteria for defining a rudder blade

A

Surface area
Profile
Aspect ratio
Design

31
Q

First element in design of a rudder

A

Surface area. Varies from 1.5 to 5% depending on requirements of the ship

32
Q

1kw =

A

1.341 hp

33
Q

Ward and quay

A

Same.

Load/disch

34
Q

Jetty

A

Protrudes out

35
Q

How does a thruster work?

A

Shape and position of the propeller are optimized so that the thrust is same on both sides

36
Q

Four environmental conditions

A

Calm weather and sea (wind 10 or less)
No current
Water depth twice draft
Clean hull

37
Q

Buoyancy is a

A

Hydrostatic force

38
Q

Hydrodynamic force is

A

Resistance offered by water to the hull