Crown Princess

1
Crown Princess

• Vessel Dynamics

2
Overview

• Ship dynamics under INS
• 2nd officers manual inputs
• Two opposing heeling responses
• Lag between wheel input and rudder/ship response
• Motion cues

3
Primary Motion

• Yaw Axis
• Heading
• Turn rate
• Turn acceleration
• Roll Axis
• Heel angle
• Heel rate
• Heel acceleration

4
Recorded Motion
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
Turning a ship

• Wheel command to rudder

9
Rudder force
10
Rudder force
11
Rudder force
12
Rudder force
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
Ships Response to Rudder
20
Direct Rudder Heeling Moment
21
Direct Rudder Heeling Moment
22
Response Lag

• Direct rudder effect
• Immediate heel response to rudder
• Sideslip effect
• Ship must first yaw in response to rudder
• Takes longer
• Much stronger

23
Saturated Rudder
24
Manual Steering
25
Motion Cues

• Positive correlation with
• Heel angular acceleration
• Heel rate

26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
Summary

• The 2nd officers commanded rudder changes faster
  than the rudder could respond
• During a 30 deg starboard rudder command the
  rudder actually port

33
Summary (cont.)

• Two effects of rudder on heel
• Short term direct response in direction of rudder
  input
• Longer term more powerful sideslip effect in
  opposite direction

34
Summary (cont.)

• Rudder commands modulated heel rate (while turn
  rate continued to increase)
• Port rudder initially slowed starboard heel rate
• But at longer term expense of increased starboard
  sideslip
• Starboard sideslip overwhelmed direct rudder
  effect producing starboard heel

35
Summary (cont.)

• Opposing long term and short term effects
  complicate the 2nd officers efforts to control
  the heel

36
(No Transcript)