Hoyer Intro (1) Flashcards

1
Q

At low speeds, what is responsible for most of the underwater resistance met by the vessel?

A

Frictional Resistance

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2
Q

What is the definition of momentum?

A

It is the quantity of motion measured by the product of mass and velocity.

(Motion x mass and velocity)

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3
Q

What is Momentum?

A

Motion x Mass x Velocity
Generally considered as motion of the ship at the time we no longer want it. Especially when action has been taken to stop it.

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4
Q

Frictional resistance depends on?

A

The wetted area and the state of the hull on a ship. (Fouling)

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5
Q

Where does pressure most likely build when encountering Longitudinal resistance?

A

Pressure builds up ahead of the ship

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6
Q

How do bulbous bows help longitudinal resistance?

A

It offerers less resistance at lower speeds.

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7
Q

Do bulbous bows offer less longitudinal resistance at higher speeds?

A

Yes, however it is roughly the same resistance at higher speeds.

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8
Q

What does longitudinal & lateral resistance depend on?

A

The ships shape and speed through the water as well as the ship’s propulsion force when at constant speed.

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9
Q

What are the four motions of a ship?

A

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

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10
Q

What part of underwater resistance plays an important role in ship handling?

A

Resistance force, which acts on the opposite side of the hull as the exerted force and in opposite direction to that force .

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11
Q

What does resistance force do?

A

It acts on the opposite side of the hull as the exerted force and in the opposite direction to that force.

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12
Q

What are the results of of propulsion force on longitudinal motion?

A

Longitudinal resistance exerts a backwards force at the bow which opposes forward motion of the ship.

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13
Q

What are the results of bow thruster force on rotational motion?

A

Underwater resistance is at the ships side mostly forward.

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14
Q

What are the results of wind force on lateral motion?

A

A beam wind will move the ship sideways through the water creating underwater resistance. In that case lateral resistance acts in an opposite direction to the wind force.

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15
Q

What is the difference between wind force and current force?

A

A beam current causes the ship to go sideways without meeting underwater resistance.

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16
Q

Is it easier to stop lateral motion or rotational motion through the water?

A

Lateral motion

17
Q

Longitudinal resistance equals what percent of propulsion force under constant speed?

A

25%

18
Q

Transverse force of a propellor working astern equals what percent of applied stern power?

A

5-10%

19
Q

How much HP equals 1 ton of bollard pull?

A

100 HP