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DP Systems Flashcards

1
Q

How many DP references or position sensor need to be online to conduct diving ops

A

3 independent systems of 2 different types

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2
Q

Describe Neap and Spring tides

A

Neap: sun and moon at 90 of each other

Spring: sun and moon in line

Spring tides will cause the biggest change in tides.

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3
Q

Describe Veering and Backing winds

A

Veering: Clockwise

Backing: Anti-clockwise

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4
Q

Max deflection of Taut wire before having to reset

A

15 degrees

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5
Q

State DP alert levels and their meaning

A

Green
Normal operational status
Clear to dive

Yellow/Amber flashing
Degraded operational status
Loss of 1 DP system

Red Flashing/Audible
EMERGENCY STATUS
No negotiations, divers up and out ASAP
Therapeutic deco if required.

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6
Q

Max thruster output allowed on DP

A

80% only for brief periods

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7
Q

State maximum vessel movements with divers in the water

A

Maximum 10m in steps of 5m
5 degrees

Cannot change both heading and distance at the same time.

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8
Q

What is the most common cause of DP incidents?

A

Operator Error

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9
Q

Max thruster output allowed on DP

A

80% only for brief periods

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10
Q

State the 5 systems of DP

A 
Power
Propulsion 
Control
Reference 
Sensors
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11
Q

Before diving operations commence the vessel should be on DP for how long?

A

At least 30mins

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12
Q

State and explain the 3 classes of DP vessels

A

Class 1; Loss of position may occur from a single fault

Class 2; Loss of position should not occur from a single fault of an active component.
One redundant engine will come online automatically

Class 3; loss of position should not occur from a single point failure, including a flooded or burnt out compartment.
Two independent control rooms

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13
Q

Examples of DP propulsion systems are;

A

Thrusters
Azimuth
Tunnel thruster
Main engines

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14
Q

Minimum number of DP control systems online for diving operations

A

2 automatic, fully redundant control systems.

In the case one fails, the other will seamlessly come online and be unnoticed.

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15
Q

Since 3 position sensor need to be online. Is it a violation of this to re-plumb the taut wire?

A

It is acceptable and required to re plumb the taut wire.

This should be done as quickly and safely as possible.

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16
Q

Examples of position sensors are;

A
  • Taut wire
  • HPR Hydroacoustic Position Ref
  • DGPS Differential Global Positioning System
  • Laser Radar; ex Fan Beam or CyScan
  • Artemis
  • FM Radar System; ex RadScan RADius
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17
Q

Some possible sources of interference to HPR Transponders are;

A

Water Jetting

Divers Bubbles

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18
Q

A vessel transponder should not be placed with what distance of subsea structures?

A

10m

19
Q

Maximum range of a fan beam laser

A

2,000m

It relies on line of sight. Fog and rain will reduce effectiveness

20
Q

Fan beam laser head oscillates how many degrees through its arc?

A

20 degrees

21
Q

For an artemis system there is a fixed antenna and a mobile antenna, where are each of these located?

A

Fixed antenna is positioned on the platform or installation.

Mobile antenna is mounted on the vessel

22
Q

Which zone is more likely to contain an explosive atmosphere on the platform?
Zone 0 or Zone 2

A

Zone 0.

Zone0; high risk area, gas mixture present most of the time

Zone1; air and gas mixture likely to be present

Zone2; unlikely to have air or gas mixture present.

23
Q

Wind speed and direction are measure by what devices?

A

Anemometers

2 independent anemometers in different locations are required to be online during diving ops

24
Q

Vessel heading is controlled by what device?

A

Gyro

25
Q

How many methods of communication are required from Dive Control to the DP Control Room?

A

2

A dedicated, hard wired system with a backup such as VHF

26
Q

Joystick is an acceptable means of vessel control during dive ops?
True or False

A

False

27
Q

In shallow water the scope of taut wires are increased?

True or False

A

FALSE.

The scope of a taut wire is reduced in shallow water.

28
Q

The bell or basket must be at least how many meters from any mooring lines or anchors?

A

50m

29
Q

How many meters above any subsea structure or wellhead must the bell or basket be kept?

A

5m above

30
Q

Shallow water does not effect the use of DP systems for dive ops?
True or False

A

False.

Shallow water will reduce the efficiency of the DP system.

31
Q

How close can a vessel approach a platform before permission from the OIM is required to come closer?

A

500m

32
Q

What vessel classes are required for DP diving ops?

A

DP2 or DP3

32
Q

What is the purpose of a DP system?

A

To maintain vessel position and heading

33
Q

Minimum number of personnel required in the DP control room during diving ops?

A

2.

One must be fully competent in all aspects of DP without supervison

34
Q

What lights are displayed at night, indicating diving operations are taking place?

A

Red White Red

35
Q

What symbols are displayed in daylight to indicate the vessel is carrying out dive ops?

A

Ball Diamond Ball

36
Q

Vessel heading changes will usually rotate around what location during diving ops?

A

The Bell or the work station

-be sure to notify divers on deck, ROV

37
Q

What are the 6 main vessel movements and specify them?

A 
Heave: up and down 
Sway: straight port and starboard
Surge: forward and stern 
Roll: Rolling port and starboard
Pitch: Rolling bow and stern 
Yaw: circular movement
38
Q

Dive ops should not be conducted within what distance of seismic surveying WITHOUT contact with the survey vessel?

A

10km

39
Q

Signage; circular, blue background with symbols in white

A) prohibition
B) warning
C) safe condition
D) mandatory

A

D) Mandatory

40
Q

Signage; circular, red boarder and crossbar over black symbol on white background

A) warning
B) prohibition
C) mandatory
D) safe condition

A

B) prohibition

41
Q

In conditions of reduced visibility, decisions about the suitability for diving from DP vessels should rest with who?

A

Diving supervisor and Captain/OIM

42
Q

Single most important concern for divers exposed to LOW frequency sonar?

A

disorientation due to vestibular stimulation

43
Q

Signage; triangle, black boarder and symbol on yellow background

A) prohibition
B) warning
C) safe condition
D) mandatory

A

B

Warning

ExamPrep (10 decks)

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