IMCA DO10 - DP Flashcards
What is the ultimate responsibility of the vessel master?
Responsible for:
Vessel
Personnel onboard
Can the vessel master veto the start of a dive?
yes
What is the responsibility of the DPO?
Station keeping
Liaison with:
Dive control
ROV
Crane
What is the responsibility of dive senior dive supervisor / superintended ?
Acts as a co-ordination.
Ensures specs met
Liaison with OMT / client
What is the responsibility of dive supervisor
On duty supervisor responsible for safety of the part of the operation he is involved in.
What is the responsibility of the client rep?
That procedures are complied with.
Does the client have the power to veto the start of a dive, and request the end of a dive through supervisor?
Yes
Safety Management:
What are the 3 key focal points the beginning of a job?
Evaluation
Planning
Risk assessment
Is the SMS enforced by legislation?
Yes and augmented by ACOPS
What is required when a change to the agreed procedures has been identified?
MOC
Who has to review and agree to the MOC?
Client
Vessel OMT
Shore based MT
What are some of the safety critical principals with regard to DP ops?
Interface between contractor / client / installation & other vessels.
SIMOP’s <500m zone
ROV monitoring of operation
Safe access & egress to water by divers
Drift trials
What must be considered when isolating thrusters & propellers?
Feasibility
Reduced capacity
Remain locked out during dive ops.
If there is a break in DP ops DP trials must be done again.
True or False
True
What interference can vessels in close proximity encounter to each other on DP?
Thruster wash
Acoustic & radio interference
Intermittent shielding of wind and waves.
What can the interference between DP vessels cause?
Less accurate position keeping
Risk to divers from other vessels that may enter vicinity should be considered in the risk assessment.
True or False?
True
What does a DP green light signify?
Full DP operational status
What does a yellow DP light signify?
Audio alarm (mutable)
Make work site safe and return to safe location
Liaison with DPO ‘
Go - No Go
Diver safety paramount.
What Does a Red light signify
Audio alarm - Mutable
Abandon worksite
Recover to Bell ASAP
DPO try hold station.
Should DPO verify move before input?
Yes
If changing the heading what needs to be established?
Center of rotation
How many independent sensors need to be on line during a DP move?
3
Can change of heading and vessel move take place simultaneously?
No
What happens if one of the 3 position sensors is lost during a move?
Vessel move is stopped
What is the acceptable range of a vessel move?
5 to 10m
What is the maximum heading change permissible?
5 degrees
When planning DP diving what does the risk assessment cover about the umbilicals?
maximum excursion permissible / closest hazard
How many meters should a working diver be physically restrained from a thruster
5 meters
How many meters should a stand-by be restrained from a thruster
3 meters
What diagram needs to be in dive control to ascertain hazard from thruster
Thruster configuration diagram
Deployment depths should in be increments of how much?
10m
The vessel diagram should show what?
Taut wire location
Reference tuggers
Work stations
Cranes
Acoustic transponders
What markings can be made for the benefit of tenders
Transverse position of thrusters painted on hull and on deck
What can be used on the bell main umbilical to prevent entry into thrusters
Chain stoppers
When chain stoppers can not be used what should be in place?
Risk assessment showing maximum umbilical lengths for depth
What should there be with regard to how much bell umbilical is paid out?
A means to identify how much umbilical is paid out
When diver and stand-by are deployed from different locations this will govern how much umbilical the working diver will have available via risk assessment.
True or False
True
What is a ‘goldola’ when using extended umbilical diving techniques?
A basket on surface suspended by vessel crane or cherry picker
Does a ‘gondola’ require a man riding crane?
No
What is the required breaking strain of a divers weak link?
<70 kg
What is an intermediate tending point?
A boat or basket on the surface where stand-by diver can be tended from.
What are the requirements of an intermediate tending point?
provision for communications and monitoring
Does a golden gate have to be on a man riding crane?
No
What is an active in water tender used for?
Deployment of diver beyond standard safe maximum umbilical length
What is passive tending?
Where two divers are on the job and their umbilcials are clipped off to the golden gate / basket
What is the caveat to active tending the working diver?
working diver curtain railed and clipped off to swim line.
what is the equation for working out max out from mid water basket / golden gate?
Which is lesser between:
C = D - 5m
C = A - 5m
And:
B < C
What are the diver considerations for DP in shallow water?
Draft Vs deployment
Thruster wash and noise
Visibility
What must be taken into account with vessel draft?
Low tide
Subsea structure heights
What happens to a DP’s performance in shallow water?
Diminishes
position references should have an accuracy of how much of water depth?
+/- 2%
In 30 meters of water depth what would be the standard deviation expected?
+/- 0.6 meters
How many position references should there be on line at one time minimum
3
Of all the position references what is required of at least one of them if possible?
Be a radio or surface reference
What is ‘scope’ in a a DP reference system
It is the radius of the operational width
What is the ‘scope’ rule?
The combination of all 3 online reference systems should not add up to less than 5m
What does shallow water do to a scope of a tautwire system?
Greatly reduced scope.
ie: short distance before need to ‘re-plumb’
What happens to acoustic systems in shallow water?
They are susceptible to interference from vessel.
How can ‘peak natural excursion’ affect acoustic references?
The dp footprint can over shoot the scope cone
What is the limitation with surface references such as fan beam or artimus?
excess range can cause issues with bearing resolution
What is the minimum horizontal distance the bell needs to be from a mooring chain?
> 50 meters
During a blow on / drift on >50m what determines safe distance? (3 things)
Risk assessment incl:
Drift trials
Recovery trials
What need 5 things need to be done if diving <50m of a mooring chain?
Continuous monitoring by transponder.
Time within anchor pattern minimised.
Twin bells not simultaneously deployed
Emergency provision for loss of bell in risk assessment.
Trapped umbilical also covered in risk assessment
How many means must a mooring chain be identified by?
two
One physical (ROV)
One can be by calculation.
If the vessel departs the mooring chain anchor pattern what needs to be done on return?
Location of chains needs to be done again
If the mooring chain is on sea bed does its position still need to be confirmed?
Yes
Mooring tension must not be adjusted mid dive.
True or False
True
Changes to the draft of the moored ship invoke what?
An MOC
Installation manager to advise in advance.
What must a DPO do during diving within an anchor pattern
continuously monitor either by radar or radio the moored vessel
If contact is lost with the moored vessel during dive ops what happens?
Immediate suspension of diving
What needs to be done with regards to permits when diving within an anchor pattern?
Reporting procedure established between vessel master and OIM
Is an ‘interface’ required between permit to work and permit to dive with regards to mooring chain / ballast adjustment?
Yes.
Is >50m horizontal clearance of a mooring chain considered acceptable during a blow on / drift on?
No
Risk assessment required after timed recovery and drift trials
<50m does the closest mooring chain need to be continuously monitored by transponder?
Yes
<50m can a twin bells be deployed at the same time?
No
<50m do emergency provisions for lost bell have to be covered in the risk assessment?
Yes
<50 does trapped umbilical need to be address on the risk assessment?
yes
Inside anchor patterns taut wire is vulnerable to being lost. What position method should be employed to alleviate this ?
Radio & fan beam systems employed.
When diving around structures & wellheads what needs to be considered?
Structure height V’s deployment depth.
Divers excursions
Active tending if diver enters structu
What is the minimum distance clump needs to be clear of structure?
5 x 5
What is the minimum distance a position reference needs to be clear of a structure?
10m
