Chapter 1 Arrival

Question 1

Shallow water effects

Answer 1

• Become significant at 1.5 times draft
• Full shallow water effects felt at 1.2 times draft

Question 2

Master’s tests

Answer 2

• Should be done in water 1.5x draft
• Include Hard turns both directions
• Backing and filling from dead stop
• Half astern times stop from 6kts
• Backing to stop while maintaining heading Backing with rudder midship
• Turning ship with thruster at 3kt and 1kt

Question 3

Engine speed during a turn

Answer 3

• Accelerating engine speed while turning will create smallest diameter turn
• Same speed throughout turn creates medium diameter
• Stopping engine in turn creates largest dia.

Question 4

Backing and filling

Answer 4

When done properly vessel can turn in 1.5 x length

• Steps

1. Half ahead, hard right
2. Half astern, hard right
3. Half astern, hard left
4. Half ahead, hard right

Question 5

Half astern to dead stop

Answer 5

• Ship will end 90degrees to original heading
• Stopping distance in deep or shallow water not much difference
• Ship will want to head into wind when rudder control is lost, and will back to wind when sternway develops

Question 6

Stopping and maintaining heading

Answer 6

1. Apply left rudder to start swing to port
2. Begin backing (prop walk will stop swing)
3. As ship begins swinging right apply left rudder and short burst ahead to swing left again
4. Repeat until vessel is stopped

Question 7

Thruster advantages

Answer 7

• At extreme ends of vessel making them very effective
• Available at all times unlike tugs
• Good lateral control without effecting headway
• Reduces need for tugs

Question 8

Thruster disadvantages

Answer 8

• Ineffective as speed increases
• less powerful than modern tug,
• will not slow a ship,
• maintenance
• unreliable at light drafts,
• no ability to control headway or sternway
• * most useful at less than 2kts. innefective over 3kts

Question 9

In shallow water directional stability

Answer 9

• Becomes more positive
• directionally unstable ship will become more stable
• This is true until vessel squats by the bow and direction stability is lost again

Question 10

In shallow water Rate of turn

Answer 10

remains essentially the same

Question 11

In shallow water diameter of turn

Answer 11

Increases

PG18

Question 12

Large course changes in shallow water

Answer 12

Speed will decrease but to a lesser extent than deep water

Question 13

When engine is stopped in shallow water

Answer 13

headway will decrease slower than in deep water. (vessel carries way longer)

Question 14

When backing in shallow water

Answer 14

heading will fall off to starboard (stern walks to port) at a greater rate as depth decreases

Question 15

Positive directional stabilty

Answer 15

• Ship tends to steady up when rudder is put midship
• Trimmed by the stern will result in positive directional stability

pg18

Question 16

Negative directional stability

Answer 16

• ship will swing at an increasing rate of turn when rudder is put midship
• Timmed by the head will result in negative directional stability

pg19

Question 17

Neutral directional stability

Answer 17

• continues swinging at the present rateor continues along current heading until external forces take over
• no tendancy to increase or decrease ROT when put to midship

pg19

Question 18

As UKC decreases directional stability

Answer 18

Increases

pg 20

Question 19

Directional stability becomes more positive

Answer 19

• as length increases
• as drag increases

pg 20

Question 20

Directional stability decreases

Answer 20

• As block coefficent increases
• As beam increases for a given length (length/beam ratio decreases)
• As area of forward sections increases relative to after sections (pivot point shifts ahead)

Question 21

Bank cushion

Answer 21

• The ships bow moves away from the shallow water because of increased pressure between bow and shallow water

Question 22

In shallow water the vessel’s midbody

Answer 22

• will move bodily sideways toward the the shallows
• caused by increased velocity of water passing between the ship and shallow water

pg 21

Question 23

Bank Suction

Answer 23

• Stern of the ship will move toward the shallow water
• caused by reduced flow of water to area behind ship, and the ships propeller being drawn to shore
• bank suction is stronger than bank cushion

pg 21

Question 24

3 Methods to reduce headway

Answer 24

1. Using engine astern- easiest, most common and least effective
2. slewing vessel on base course
3. large heading change including a complete round turn

• * ship going 12 knots can lose 2-3 knots at the completion of a round turn without reducing rpm

pg 24

Question 25

Loss of speed during heading change rule of thumb

Answer 25

ships can lose 25-20% of headway for every 90 degrees of heading change

Question 26

Speed through the water with prop wash

Answer 26

*When engine is astern*

• Wash is astern of vessel = Greater than 2kts
• Wash begins making its way up the vessel (at stern) = 2kts
• Wash at midship = dead in water

pg 28

Question 27

High sided ships feel effect of wind

Answer 27

at 3 times the vessel’s speed

pg 32

Question 28

Loaded tankers will feel wind effect

Answer 28

at 5 times the vessel’s speed

pg 24